Are you looking for free circuits, ideas and solutions? Are you interested in getting personalized help regarding an electronic circuit project which you perhaps couldn't grasp correctly?
Feel absolutely free to contact me through the comment box below the articles for getting quick solutions to your queries. I'll try my best to get it done for you absolutely FREE!
You can also communicate with me through the following social networks:
Gourab Majumder says
Hi I have to generate a code for a three phase two level inverter by using arduino
Swagatam says
Hi, I am sorry, my Arduino knowledge is not good enough, so I may not be able to help you with this request.
Eric Hamilton says
Hi, do you have a circuit for a 48V under / over voltage alarm. I need a wide range of settings as I will be using it to start a generator on an off grid solar system when batteries get to a preset low level, then stop again when voltage has risen to another preset level
Thanks
Eric
Swagatam says
Hi, can you please specify the under and over voltage cut off levels?
Eric Hamilton says
Hi Swagman
Thanks for the reply, I would like to be able to have the relay cut in around 39-40Volts, and out again around 46-48 volts.
Thanks
Swagatam says
Hi Eric,
You will have to modify the last circuit from the following article to satisfy your requirement.
https://www.homemade-circuits.com/opamp-low-high-battery-charger/
Please comment under the above article, for further discussions regarding the modifications.
Eric Hamilton says
Hi Swagman,
I really only want to sense the voltage and operate a relay, this will in turn start a generator, the circuit supplied appears to be an overkill for the job.
I have seen a circuit that i was unable to read due to the poor quality, but it used a LM393 comparator.
Any Ideas
Regards
Eric
Swagatam says
Hi Eric,
since you require two cut-off thresholds, therefore you will need an opamp. If you would need a single ON/OFf point then the circuit would be much easier, but even then an op amp would be required.
LM393 is a comparator similar to an op amp and that would also work.
Moreover your operating voltage is 48V while most op amps and compaartors cannot work with that voltage so you will require dropping resistors and zeners.
The circuit suggested by me is the easiest and the most suitable for your application.
Anything simpler than this might not fulfill your requirement correctly.
David Neil Kristensen says
Dear Sir,
Please tell me if your 2 transistor preamp will be good in a HIFI setup ???
How much does the preamp amplify. I dont need much amplifiation.
C1 an C2 should be of high quality capacitors if used in HIFI setup.
Polystyrene, Polycarbonate or Paper capacitor.
Where should an stepped attenuator be placed, mayby before C2 ?
How is C2 polarized, is black plus ?
Best regard/Yours sincerelly.
Swagatam says
Hi David, can you please ask this question under the same article which you are referring to, so that I can see the diagram which are you are referring to.
David Neil Kristensen says
I found it under the 5 simple preamplifier circuits explained.
1) Preamplifier using two Transistors
Swagatam says
yes the 2 transistor preamp will be good in a HIFI setup.
https://www.homemade-circuits.com/small-amplifier-circuit/
C1 can be any ordinary disc ceramic capacitor, C2 can be an electrolytic capacitor. Black is minus, white is plus.
David Neil Kristensen says
Neither ceramic or electrolytic capacitors are good in the signal way in a HIFI setup.
They sound bad.
Use only polycarbonate, polystyrene or paper capacitors.
Or if the capacitors are large they should be paralelled with a good capacitor like above mentioned.
Andrew Forrest says
Hi there Swagatam , how can the sinewave driver circuit be connected to a transformer with no center tap connections only single 12 v input
Regards
Andrew
Swagatam says
Hi Andrew, You will need a full bridge driver circuit for that, with a specialized driver IC. This IC will need to be fed with a sine wave signal input
Bill Miller says
Hi,
I have a circuit question regarding upgrading an internal circuit board for rc truck and wanted best possible for my project. I am trying to make rc truck go quicker, agile, further distance, etc. Can you give me any recommendations for my project? Would greatly appreciate any suggestions for my project and have a great weekend.
Thanks,
Bill Miller
Swagatam says
Hi, Although I do not have a sophisticated RC truck circuit, I have a similar looking circuit which operates a trolley using remote control. You can find it in the below given link. Hope this helps.
https://www.homemade-circuits.com/remote-controlled-trolley-circuit/
Bill Miller says
Hi Swagatam,
Thanks for the respond on my question regarding my project and look at the website and your suggestion. I really appreciate your assistance and have a great weekend.
Thanks,
Bill Miller
Swagatam says
It’s my pleasure Bill,
You too have a great weekend.
Bill Miller says
Thanks Swagatam for the assistance and best of luck with your future projects as well.
Thanks,
Bill Miller
Swagatam says
No problem Bill, all the best to you!
Bhaskar Challapalli says
I have used a Mosfet controlled fan speed control circuit IRF 740 Mosfet driver with a PWM Driven Optocoupler I faced problem in decreasing the fan speed pl suggest rectification
When I increase the duty cycle of PWM, it successfully increases fan speed accordingly
When I decrease the PWM duty cycle slowly, fan still runs at same speed, and doesn’t slow down
When I turn off the PWM, fan stops with a sudden jerk, and my MOSFET blows off after becoming too hot
The same circuit works well for dimming of resistive loads like incandescent bulb
So I wanted to know, what modifications do I need to make in my circuit, to safely handle the decrease in fan speed?
I want to make sure that after operating the fan at 100%, even if I turn off the PWM suddenly, the fan should still stop gradually and not with a jerk.
Swagatam says
Is your motor a DC motor?
Which circuit did you use for controlling the speed of your motor?
ch bhaksar says
I need 150khz mosfet switching driver IC selection for 40 amps 600v for inductive load(to drive 1.5 hp 240 v ac water pump motor )
you are requested to suggest the better operating frequency
Swagatam says
What is the purpose of the circuit? Is it for controlling the motor speed?
Bhaskar Challapalli says
i am planning to control the power transfer to the single phase motor water pump (1.5 HP=1.12 Kw) with out changing the frequency/ speed
Please suggest the best switching speed, suitable driver for 40n60 Mosfet 40 Amps 600v to overcome switching problems and avoid Rf interference effects
i selected the Mosfet ratings as per below calculations
Vrms 230 V , Vpk= 1.414*230= 325 v, overload factor 150% 325*2
=487v, i have selected 600 v rating Mosfet
Motor Current= 1.12kw/230v/.85(PF)=5.71 A
Motor starting Peak currents Max 5 Times of rated current
5.71*5=28.6A Rms
Staring Current Peak Value 1.414*28.6= 40.4 A
Here non continuous Staring Currents range Covered Design Over rating Margin
so I have selected 40 Amps rating Mosfet
Scott Gilden says
I have a 2005 Polaris UTV. The voltage regulator is incorporated into the ECM/PDM and has failed. Could I bypass the ecm and install an external voltage reg?
Swagatam says
Sorry, I am not sure whether the vehicle system would allow this or not? I can provide you the circuit idea of the regulator but I am not sure how the vehicle electronics would react to it?
Scott Gilden says
That would be great.
Thank You
Swagatam says
OK, could you please tell what is the maximum voltage output from the UTV alternator? And at what voltage level would you want the regulator to control the output?
scott says
65 v at 5000rpm. I think around 14v would be sufficient
Swagatam says
You can try the following concept:
https://www.homemade-circuits.com/wp-content/uploads/2021/02/shunt-regulator-alternator.png
Feed the input to the circuit through a bridge rectifier.
TIP122 could be replaced with a TIP35 for more current handling.
The zener diode could be replaced with the 14V zener diode.
karl eakin says
circuit with IC1 LM 567 can pin 8 activate a relay. ?
which capacitor do i need to change value? to control latch time on/off.
goal for this project is arm and disarm unit remotely and when a Britch is made send signal to a smart phone.
do you think that kind of circuit is possible?
Swagatam says
Can you please specify the exact schematic you are referring to? I don’t seem to find the relevant circuit related to our discussion.
Parduz says
Hello from Italy!
I’d need a small circuit to regulate the current for a LED strip, to be installed on my motorcycle.
I need to limit the current ’cause the strip have to stay cool and not overheat.
I tried a small LM338 circuit but it fails (and become VERY hot) and someone on reddit told me that it is ’cause there’s not enough DeltaV between the source (the ~13V of the bike) and the 12V required by the LEDs.
Do you have a working solution?
Swagatam says
Hello Parduz,
If LM338 circuit is heating up for you, then you can try a MOSFET or a BJT based regulator, as explained in the following article:
2 Best Current Limiter Circuits Explained
Let me know if you have any further questions.
billy mc court says
hello Swagatam
i have a gas fire it is controlled by Magiglo VAL0764 Remote Control Handset & Receiver
i think ULTRASONIC TRANSDUCER 40KHZ is failing in the receiver it makes a jerking clicking sound
can i replace it with any type ULTRASONIC TRANSDUCER 40KHZ
don’t know anything about electronics but solder
could upload a picture where ?
thanks, billy
Swagatam says
Hello Billy, according to me all types ultrasonic transducers should be able to detect 40 kHz frequency, so you can use any type of transducer.
billy says
hi Swagatam
thanks for the reply
in your opinion do you think it is a 70% percent chance it is the ULTRASONIC TRANSDUCER 40KHZ that’s causing the problem
it says to but in four 1.5 v batteries into the receiver = 6v did that and it jerks
I replace them with 4 bad batteries = about 4.5v and it works great
what do you think
thanks, billy
Swagatam says
Hi Billy,
If the jerking stops with the use a lower 4.5V, then it could be an over voltage issue for sure. It is not a transducer issue.
In that case you should stick with 4.5V or maybe a 5V battery, if a 5V is available.
Haiwan says
Hello Swagatam,
I am looking for an circiut to control 220 Volt Phase for an Electric Heather with a Fan using 220 Volt.
Just want a phase shift circuit for this.
This circuit must have all the components with the part number.
I thank you for this,
Greatz,
Haiwan
Swagatam says
Hello Haiwan, You can try one of the concepts explained in the following article:
220V Light Dimmer and Ceiling fan Regulator Circuit [Using Triac and Diac]
Haiwan says
Thanks Swagatam, i will check this and if i have any porblems I will contact you.
gr
haiwan
Rosario says
Hi engineer. I have a good 220V AC-28V AC voltage transformer. I would like to use it to build a stabilized power supply of which I have a kit. However, this needs to receive an in a voltage of 26 V AC. What is the best way to achieve this? Thank you
Swagatam says
Hi Rosario, your 28 V AC cannot be reduced to 26 VAC, so I am afraid this transformer cannot used with your kit.
Instead you can use a simple LM338 based regulator circuit to build a stabilized power supply.
Paul Kibedy says
Hello
Like to know,what is the difference between mic pre-amp and guitar pre-amp or audio pre-amp
like to build one,but not sure what to do…………..thanks.
Swagatam says
Hi, all of them are similar with their basic function, however their preamplification specification can be slightly different depending on the application.
Paul Kibedy says
Hello;
Thanks for the reply,you said the specification can be slightly different depending on the application
but in what way can be slightly different depending on the applications,,,,,,,,,,,thanks.
Swagatam says
Hi, the sensitivity, amplification and gain may differ slightly.
Vinu says
My name is vinu. I am a grade 7 student. I need a sensor which can deduct the flow of saline in an iv line. It should not touch the liquid probably a light sensor.
Swagatam says
Hello Vinu,
You can probably do it by sticking a tiny solar cell on one side of the IV line, and placing an LED lamp on the other side. The soar cell then can be connected with the milli-voltmeter to check the turbidity of the saline solution and detect the saline level.
Abdulkarim says
Sir I Need Help Me Microcontrol Circuit Use Timer 555 Or Cd4017 On 20minute Atleast Delay 5 In Off ,..! Instead Of Arduino Or Cd 4060 Circuit
Biswajit Ghosh says
I want to interface the following Current Transformer with an ESP32 (3.3V system).
https://www.homemade-circuits.com/wp-content/uploads/2023/01/current-transformer.jpg
Can you suggest me a suitable circuit (with values of the components) required for it?
The transformer gives current output in the range of 0-50 mA for loads up to 50A. But ESP32 can sense only voltage. So, we need to convert that current to voltage (in a range which is acceptable by the ESP32)
Thanks in advance.
Swagatam says
ESP32 is a low-cost, low-power system on a chip (SoC) series with Wi-Fi & dual-mode Bluetooth capabilities!
So I can’t figure out how you want to connect a current transformer with it.
Please explain in details the sense pinouts of the ESP32 where you would like to integrate the current transformer and also the purpose.
Biswajit says
Swagatam thank you so much for your reply. What I need basically is a Current to Voltage converter which will convert current in the range of 0-50 mA to voltage in the range of 0-3.3V. I would then connect the Voltage output to the ADC pin of the ESP32 and measure the voltage to find out the current flowing through the transformer.
Swagatam says
Thank you Biswajit,
You can simply do it by connecting a low value resistor (shunt resistor) across the secondary output wires of the current transformer. The resistor will convert the current into a voltage drop across itself. You can start with a 50 ohm resistor and check whether it produces a 3.3 V range of voltage across it or not. You can adjust the resistor value accordingly until the correct range of 3.3 V is achieved.
I also have a related article in this blog, you can check it out here:
Monitoring 220V AC Load Current using Current Transformer [Circuit Diagram]
Rich R says
I am trying to make a 110v AC to 110V DC cicuit. When I place a bridge rectifier across the mains, the voltage increases to 169V DC. I installed a 470uf capacitor but the voltage remains high. I need to operate a controller at 110v DC approximately 2 amps. Do you have a circuit I can use for this purpose? Thank you, Rich
Swagatam says
I think you can try the second circuit from the following article:
https://www.homemade-circuits.com/0-300v-variable-voltage-current/
The R2 resistor controls the output current. You can tweak the value using the following formula:
R2 = 0.6 / max output current
abdul says
how to make simple programmable timer setup with cellphone and digital display
Ajeet kumar says
sir,
I have battery and charging power plant, the capacity of battery is 48 v. For this i want to make circuit that it shows the mains ac supply failed and low voltage indicator .low voltage range will be below 47 volt.
sir kindly help.
Swagatam says
Ajeet, for the mains failure indicator you can try the following circuit:
https://www.homemade-circuits.com/wp-content/uploads/2022/12/mains-failure-indicator-circuit.jpg
for low battery indication you can refer to the following article:
Low Battery Indicator Circuit Using Two Transistors Only
ABdul says
sir how to make security alarm
Prithwiraj Bose says
Hi Swagatam,
Can you please create a post to share a circuit for controlling AC Mains Fan using an Arduino. It would be best if the input to the Arduino is taken from an TSOP1738 or similar infrared sensor. I have see some similar circuits on the internet, they are confusing because they do not elaborate the usage of various components in the circuit. For example, most of the circuits use a 4N35 Optocoupler and there is a zero cross detection stage. Can you please explain/confirm, if this stage is required, when I power my Arduino with a dedicated DC power supply. I see most of these circuits are trying to run the Arduino from Mains power, but when you share your circuit, please keep the Arduino power supply part simple/separate and from a DC source.
Swagatam says
Hi Prithwiraj,
My Arduino knowledge is not good, so creating any Arduino based project can be difficult for me. All the Arduino based projects posted in this site were written by another author.
TOM DUGAN says
I have a seven foot DIY outdoor Menorah made with nine 99¢ store flickering LED hollow pillar candles each powered by a 3v CR2032 coin battery (no resistor). Every 24 hours I manually replace the old batteries and light the next LED each of eight nights and would like to replace them with a very simple timing circuit or controller. You activate the Menorah and the center and first LED candles light, followed every 24 hours by the next candle over eight days. They all stay lit until you switch it off.
I would like to automate this with a very simple and cheap circuit I can share with kids as a DIY project. This could be a popular project for some of your readers and I would be happy to pay for your time. I can solder and can read a schematic but other then real basics I am not an electronics guy. I am completely open to any suggestions, but it seems there are a few options based on the design of the Menorah.
First one circuit board with wires going to each LED. Second, the plastic candles are hollow so one 24 hour circuit board in each candle could power it’s LED and send a wired trigger signal to start the 24 hour timer circuit in the next candle etc. Third, if not too expensive, individual circuits in each candle that activate each LED in 2,3,4,5,6,7 and eight days that I turn on at the beginning of the cycle. I would like to use a small AC to DC transformer to power this, but there is enough space in each candle for double A or C batteries if needed. I don’t think this needs a relay because the flickering 3v LEDs currently can go over 24 hours on a single button battery so the power draw is maybe 50ma?
It is absolutely not needed but if not complicated – it would be nice to resent the LEDs to a certain day in case something goes wrong in the middle of the sequence – however I would be overjoyed just to get this automated at even the lowest level! THANKS ALL!
Swagatam says
I think I already have a similar looking design in this blog. Separate circuits won’t be required for the individual candles, a single circuit will be able to handle the entire sequence of 8.
https://www.homemade-circuits.com/digital-christmas-candle-light-circuit/
Tom Dugan says
Swagatam – this looks great – thanks so much for your help!
Swagatam says
My pleasure Tom, glad to help!
TOM DUGAN says
Hi Swagatam, Is this your first name or nickname? It is a pretty cool name meaning “Welcome” in Sanskrit! I think I found a minor mistake reversing pins 1 and 5 outputs in your schematic which would light those LEDs out of sequence. Also – any suggestions for the values of the resistors and capacitor in 4060 – I don’t know where to start with that! I adjusted your 25 light circuit to 7 for a Menorah – how can I post a JPEG for you to take a look?
Swagatam says
Thank you Tom, it is my first name! That’s right, it means welcome in Hindi and sanskrit
Can you please elaborate on what you meant by “I found a minor mistake reversing pins 1 and 5 outputs in your schematic….”
Regarding selecting the 4060 timing components, I have explained it in the following article, under the heading: “Calculating RC Timing Components”. Please check it and let me know if you have any further questions
https://www.homemade-circuits.com/how-to-make-simple-programmable-timer/
TOM DUGAN says
HI Swagatam – Sorry – I should have said “reversing the listed sequence of pin 1 with 10” (NOT reversing pins 1 and 5 outputs). I found a pinout of the 4017 IC at eleccircuit.com and it showed the following output. Out 0 = pin 3 / Out 1 = pin2 / Out 2 = pin 4 / Out 3 = pin 7 / Out 4 = pin 10 / Out 5 = pin 1 / Out 6 = pin 5 / Out 7 = pin 6. In your schematic you have the pins listed in this order (sequence?) 3, 2, 4, 7, 1, 10, 5, 6. So it could be someone’s typo reversing 1 and 10. Also did I get it right that 4017 pin 13 would go to pin 6? I have an adjusted schematic for you to check if you tell me how to send it to you.
Swagatam says
Thank you Tom, for the clarification and for pointing out the typo! I have now corrected the mistakes in the diagram and updated it appropriately. You can check it out.
I have explained the 4017 pinouts elaborately in the following article, which you may refer to for more info on the same:
https://www.homemade-circuits.com/how-to-understand-ic-4017-pin-outs/
Pin#13 of IC1 would go to Pin#1 of IC3 according to the corrected diagram, since 25 LEDs are involved.
For submitting your diagram you can upload it to any “free image hosting site online” or to your Google drive account and send me the link here, I will check it out and provide my feedback to you.
TOM DUGAN says
Swagatam, This is for a Menorah so there are only 7 lights that need to be sequentially lit after the circuit starts (the center and first LEDs are wired direct to the power source so only LEDs 2 through 8 need to be part of the 24 hour sequentially lit LEDS. Here is a link to what I thought the circuit would look like for the 7 24 hours LEDs: https://drive.google.com/file/d/1WvRvEn1pk6-8MAZw9q_NSox6XgirOieT/view?usp=sharing Please change if needed.
Swagatam says
Hi Tom, the PNP transistor will not be required in this design, it can be removed. And the pin1 and pin10 must be swapped with each other. Rest everything looks perfect to me.
TOM DUGAN says
Here is the Dollar Store Menorah up tonight – operating with manually inserted coin batteries:
https://www.homemade-circuits.com/wp-content/uploads/2022/12/menorah.jpg
Here is your 25 LED circuit I adjusted for 7 Menorah LEDS – please edit if needed so I can try to use your circuit this year:
https://drive.google.com/file/d/1WvRvEn1pk6-8MAZw9q_NSox6XgirOieT/view?usp=sharing
Swagatam says
It looks very nice indeed, thanks for updating the pics.
TOM DUGAN says
Hi, I think I have the final circuit with all of your changes – could you give it one more look?
I did swap pins 1 and 10 but doesn’t that bring us back out of sequence on outputs 4 and 5 (Out 4 = pin 10 / Out 5 = pin 1)? I also adjusted the voltage to match the 9 volt battery. Thanks for your final OK!
https://drive.google.com/file/d/1eQqCPcw2VSJPevUIDGSXehgizmFP1VNk/view?usp=sharing
Swagatam says
Hi, It seems you missed the LEDs…the LEDs should be in series with each of the SCR anodes, and pin1 and pin10 are not in the correct sequence. Remaining circuit looks OK to me.
For the pinout sequence please refer to the following datasheet:
https://www.ti.com/lit/ds/symlink/cd4017b.pdf?ts=1671448205885&ref_url=https%253A%252F%252Fwww.google.com%252F
Tom Dugan says
Hi Swagatam – thanks for your patience and the info this should be my last post on the LED Menorah.
I have never done this before so most of the info you sent is WAY over my head. In fact the Silicon Controlled Rectifier was not mentioned in your instructions so I took it out because I mistook it for a second LED! It is back and I now understand its function is to power its LED once the timer output pulse(?) closes the gate and power flows through the LED connection. HOWEVER I still have no idea what to do with IC 4017 pin 13 – “Clock Enable.” I connected it to pin 6 because in your original 25 LED circuit it was connected to the output following the last Christmas (25th) LED. On the Menorah, pin 6 would be the output following the last (7th) LED to be lit. PLEASE let me know where it goes – I am completely lost on that final point. Here is an updated schematic:
https://drive.google.com/file/d/10E2Ba3qfpNAFf_XmwsiMwpW1i1esBFqt/view?usp=sharing
INTERESTING QUESTION ONE: The existing Menorah LEDs are each powered by a tiny CR2032 3v Coin Cell Battery without anything else. I understand that the two ICs and components are needed for the complicated timer function – but what happens at the IC 4017 activated outputs? Is there a “pulse” or an “electrical flow”? If the activated output is continuous – couldn’t the 80ma LEDs connect direct to the pin and then to ground if the power supply was lowered to 3V (which is the lowest voltage range for both ICs)?
INTERESTING QUESTION TWO: I have read that IC timer circuits are inaccurate over a few hours because the capacitor used leaks amperage throwing the count off. Is that true? If so, is there a way to correct this or will a higher quality capacitor solve this?
Swagatam says
No Problem Tom, I am always happy to help!
Yes SCRs are required across the outputs so that they can latch the LEDs permanently ON, as soon as they are switched ON.
Pin#13 requires a ground connection for enabling the 4017 output sequence to carry on its sequential movement. If the pin#13 is connected to the positive line, the sequencing process instantly freezes and stops.
In your circuit if you connect pin#13 to ground, then the 4017 output sequencing would go on progressing until it reaches the last pinout pin#11 and the then the whole sequencing would reset back to pin#3.
Connecting pin#13 to the pinout immediately after the last LED pinout causes pin#13 to go HIGH, through the positive pulse received from pin#6. This instantly “freezes” the whole sequencing function and it remains “frozen” in this position until power is switched ON/OFF or pin#15 is momentarily connected to the positive line.
However, I think pin#13 connection is not relevant to your application, because the SCRs would be latching the LEDs permanently ON, so even if the 4017 IC is reset if won’t affect the LED illumination.
I don’t think coin cells would be able to power the ICs and the LEDs together for many days….they would hardly last for maybe 1 day or so.
1) The outputs from the 4017 switches ON and then OFF as the sequence progresses from one pinout to the next. However, since SCRs are used the LEDs would remain permanently switch oN as soon as the relevant SCRs are turned ON. That is exactly why SCRs are used.
2) Yes, 4060 timer can drift away from the set timing, however in our circuit the use of diode at pin#12 of the IC 4060 ensures that the IC 4060 is reset each time a 24 hour cycle is completed which enables its timing capacitor to discharge fully and start afresh. This helps to reduce the time discrepancy to a great extent.
Yes, a tantalum capacitor for C1 will help to enhance the timing accuracy.
Other alternative is to use a crystal with the IC, but I do not have this circuit with me right now.
TOM DUGAN says
Dear Swagatam, “Pin 13 to Ground” – Thank You, Thank You, Thank You and Merry Pancha Ganapati! You certainly are a giving person, sharing your incredible knowledge and patience with an electronics newbie! Your detailed explanation really helped me understand your circuit! Please check the email address used to contact me. if you can’t do that email me from an address you can access for my thank you.
Swagatam says
Its my pleasure Tom! I am glad I could help!
You can get in touch with me on hitman2008 @ live.in
Ian Waters says
Hi,
Do you have a template for the PC board used in the 50m dog “trainer”?
I am building something similar but my knowledge is limited and designing PC boards is something I know nothing about, besides I would be inventing the wheel.
Thank you
Swagatam says
Hi, I do not have the PCB layout, but I do have the circuit diagram. The PCB layout can be obtained from any online professional in this field.
abdul says
hi sir please I have ups transformer so give me circuit diagram about 1kwatt simple circuit with using CD 4017 or SG 3524
Swagatam says
Hi Abdul, do you want to make a square wave inverter or a sinewave, and what is voltage rating of your transformer?
abdul says
OK show me how make it
Swagatam says
I asked you about your requirement specifications in the previous comment!
abdul says
yes I mean me I went make square wave or sinewave inverter or pure is ok
Swagatam says
You can try the first schematic from the following article:
https://www.homemade-circuits.com/modified-sine-wave-inverter-circuit-2/
Mukesh Rajpali says
Hi,
I am regular follower of your website. You are absolutely genius in electronics and the way you represent and explain the technicals here.
I am new to electronics and do little projects my own.
I need help for designing surge protection circuit of 10KVA for led street light having MOV and fuse resister. I don’t want to use gas discharge tubes.please help provide design file.
Thanks.
Swagatam says
Thank you Mukesh for your kind words, and Glad you liked my website!
Before I try to provide a solution I wanted to know how is your LED lamp powered? I guess it is powered from 220 V mains AC and not through a battery system.
Kindly let me know about this?
Mukesh Rajpali says
Yes its from AC 220v main. Wattage of street light are from 24W to 110W.
Swagatam says
OK, and what is used for the power supply, is it a transformer or an SMPS. If it is an SMPS then it may already have an NTC and MOV based surge protection system in-built?
Mukesh Rajpali says
no, its only for surge protection. it will be connected to LED driver of street light or flood light.
Swagatam says
You can try the last two circuits from the following article:
https://www.homemade-circuits.com/how-to-make-simple-ac-mains-surge/
Abdulkarim says
sir how are you so i have 6.68v 0 6.68 ups transformer how to bult simple inverter circuit
Swagatam says
Hello Abdulkarim, You can use it to build any inverter circuit from the following article.
7 Simple Inverter Circuits you can Build at Home
G White says
Sir:
I am a retired older person just getting back into electronics. Having grown up designing around tubes/valves I am very lost in the modern IC world.
Is there a reference source that will point out which IC family to begin research, i.e.: datasheets, etc., for a particular application or block in more complex applications?
Thank you for your time.
Gary
Swagatam says
Thank you Sir, I appreciate your interest and glad you are getting back to electronics.
I would recommend exploring the IC 555 which is an universal electronic workhorse device with unlimited applications.
Below are the couple of links which you can explore for learning about the IC 555
https://www.homemade-circuits.com/timer-ic-555-explained/
https://www.homemade-circuits.com/category/555-ic-circuits/
Let me know if you have any further queries.
abdul says
sir how to make mobile phone charger using 3.7volt
Swagatam says
You will need a boost converter to convert the 3.7 V to 5 V and then you can use it charge your mobile phone.
qbdul says
How can make it
simply
Swagatam says
You can try the second circuit from the following link. Remove C3, D2, D3 from the circit since you won’t need the -5V supply.
https://www.homemade-circuits.com/how-to-make-simple-boost-converter-circuits/
ansari says
Hello sir,
I came across this load cell (https://www.homemade-circuits.com/weighing-scale-circuit-using-load-cell-and-arduino/) project of yours that I am interested to mimic and implement.
I want to incorporate a “milligram” sensitive measurement in the range of the weighing. Is that possible to do so using this setup?
Hoping for your help and guidance!
Thanks and Regards,
Ansari
Swagatam says
Hello Ansari,
You can surely try the concept, however since I am not good with Arduino coding, won’t be able to suggest any modifications in the code for your specific application. You may perhaps try asking this question in an Arduino forum online, somebody might be able to help you out.
abdulkarim says
good after noon sir
please
how to make simple switch like
1 clap switch on and off
2 or using sound switch on and off
Swagatam says
Hello Abdulkarim,
Please use the search box and search for “clap switch” and “sound activated switch” you will be able to find them easily in this blog.
GUY MARCHAND says
Hi there,
I am in trouble to build or buy a 2.4Gz transmitter and receivers for the model raailway I’m building The scale is “I” (32mm to 1 m )At the moment, an electro railcar is built . Some more locomotive are planed to be built. So, from the transmitter I must be able to send commands by radio to these various rail workers , being understood that the commands are the same for any engine : they should be : 4 for speed: very slow, slow , regular , full speed . 1 for “uncoupling” ,1 for “stop” . all are get onboard the engine with relays working with 12 v DC (battries are on the engine . There is also an other battery with 3.6 V for the receiver. An other point is the antenna: all the stuff is inside the cabin which is made of iron sheet . The antenna should be on the roof of the engine . Ho to build it ? I am very sorry to have made a very long description of my project . Thanks a lot for your help . Regards . Guy MARCHAND .
Petrus says
Good day
I use a 50A 12V DC battery charger to charge my backup system. The charger gets very hot during the charging cycle. I want to install two 230V AC cooling fans that automatically comes on and off for the charging cycle. There is a 5mm LED that indicates when it is charging. I thought to use that to switch the fans with a relay, but I do not know where to start. Please help me with information on how to do it.
Thank you
Petrus.
Swagatam says
Hi, I think a relay may not be required, you can connect the fan directly to a transistor driver circuit as shown in the following figure:
https://www.homemade-circuits.com/wp-content/uploads/2022/11/transistor-fan-driver-for-heatsink.jpg
If you think a relay driver would be better in that case you could try implementing the following design
https://www.homemade-circuits.com/wp-content/uploads/2022/04/relay-driver-circuit.jpg
Let me know if you any further doubts.
Petrus says
Hi, the fans are 230V AC, so the fan circuit must be isolated from the trigger circuit – that why I thought a relay will do the trick. I just need to switch the relay from an existing LED that probably runs at 2V DC.
Thanks.
Swagatam says
OK, no problem, then you can use the relay version of the circuit:
https://www.homemade-circuits.com/wp-content/uploads/2022/04/relay-driver-circuit.jpg
I hope you know how to configure the contacts of the relay to operate the fan via 230 V AC.
abdulkarim says
sir please how can I make micro controller using some minutes 118 minutes off 2 minutes on 118 off 2 minutes at least 118 off 2 minutes on how can I do it sir
Swagatam says
Hello Abdulkarim, you can try modifying the following concept to get the intended results:
https://www.homemade-circuits.com/arduino-2-step-programmable-timer-circuit/
Claudio says
Dear all,
I have a mosquito killer lamp that it doesn’t work properly.
I changed the battery and now the light appears works fine but the electric mesh doesn’t work.
I’d like to understand the circuits of my device in order to learn, with a real condition, something new when I try to repair it.
I found a problem with the electrolitic capacitor (swallen on the top) and the area close the a transisor (BT169D) was burned.
I prepared some photos and other informations regarding the PCB but I don’t know if someone wants to help me to, with some explenation
on the circuit. Let me know if it is possible to send more details. All the best
Claudio
Swagatam says
BT169 is an SCR not a transistor, so it is strange why an SCR used in your circuit? I have never seen an SCR in a mosquito swatter bat so far. You can try replacing the swollen capacitor and the SCR both and check if that helps to restore the working of the bat.
Claudio says
Dear sir,
thanks for your reply; I changed the BT196D thyristor and I checked that tha lamp works and also the tension is around 780V DC on the wires to the mesh…
I’m quite fear fair to create a short and test the grid, can you suggest the section of the wire to do this? (clearly I’ll do it with max attention so)
I prepared some photos and documentation of the pcb, I tried also to skect a schematic but I need an help to understand how it works.
There is a possibility to have an help with theory of my device?
Thanks in advance.
Claudio
Swagatam says
Hi Claudio,
That sounds good! you can upload the schematic to any free online image hosting site and provide me the link here, I will check it out and if possible try to explain it to you.
Claudio says
Great,
this is the link to download some photos and info:
https://we.tl/t-6WmwrrqZR5
Thanks in advance.
Claudio
Swagatam says
I tried to understand the stages but unfortunately I couldn’t, since the pen drawing is not so clear and the schematic has too many interconnected components. However, I guess you can try shorting HV1 and HV2 points since these are the points that are supposed to go the mesh. Moreover there’s no other way to confirm whether the bat is working or not.
Claudio says
Thanks sir,
I have done the short test on HV side of PCB, with a powerful spark, it is ok.
I controlled also the mesh net; on one side the wire makes many round from the bottom to the top of the lamp and finish without interrupted area;
at the same time, on the other wire, it makes many round like the other one, alternating; aslo this circuits, with continuity and without particular dent, I controlled the continuity (START-END) on each circuit and it appears ok. Probably the device is ok, replacing the burned thristor, but
I’d like to learn much better the circuit.
In your opinion, if I prepare a better drawing, instead of the previous one you can produce a schematic drawing in order to explain the function?
Thanks a lot for your patience.
Swagatam says
Hello Claudio,
I appreciate your interest, however the circuit which you have shown is quite big and will require a lot of time to understand and explain, which can be difficult for me due to lack of time. I hope you will understand and bear with me.
Claudio says
Don’t worry,
I appreciate your answers.
All the best.
Claudio
Swagatam says
Thank you for your understanding, appreciate it!
Göran Axelsson says
Hey!
Have a question about my project for my grandson Gocart.Pwm dcmotor 36 volt brushless.
Designing an own control, thinking with 2 1000 watt motors connected in parallel.
The control basically consists of LM339. mos driver TC4427. power stage 6 pcs parallel connected IRFP3206 gate resistor 33 ohms on each mosfet. 2 pcs SCHOTTY MBR30C100.
current limiting resistor of 1.5 mohm I also thought via which the LM339 can also control. So that the current does not increase too much.
What I’m wondering about is that no filters (suppression circuits) are needed over the mosfets and the motors.
For example, DC motors generate voltage themselves when the speed is reduced.
If you are interested. How do I send a picture of my clutch
Thank you for your reply
Best regards Goran
Swagatam says
The back Emf from the motor can be generally suppressed using capacitor and diode connected parallel to the motor coil. If you already have schottky diodes connected parallel to the motor coil, then you do not have to worry much. You can further add a 3uF/400V PPC capacitor in parallel for added suppression.,
Goran says
Hi! Will test it. Thanks
Patrick Chapman says
Hello Swagatam.
I trust that you are keeping healthy and fit.
I am sorry to bother you again but I wonder if you can help me.
I have searched the internet for a circuit for a circuit that will effectively test a TL081 single JFET op amp.
I have found several circuits, some with one led and some with two leds to show if the op amp is working. I have built a few of these test circuits but here is my problem. I have a variable power supply with current limiting as well. I built this PS from a Smartkit 1138 0-30 volt 3 amp kit several years ago and it has served me well. I recently added a digital voltmeter/ammeter to it and it stopped working. (my fault) So I removed the meter and it still did not work. So I tested the four transistors and replaced two of them and it still did not work. The board has three TL081 op amps so I tried building a test circuit and the led flashes with all three amps. So I built one with two leds and only one led flashes instead of the two alternating like a flip flop. So I bought three new TL081’s and fitted them and it still does not work. So I put the new op amps in my test circuit and again only one led flashes.
So now I am looking for a test circuit the definitively tells me whether the op amp is good or bad. My power supply gives me no voltage output and the current limit led stays on all the time. I have tested all the diodes and resistors and I cannot find the problem. If you can help me with this I would be very grateful as I am lost without my power supply and a new kit is no longer available.
Thank you and best regards.
Patrick Chapman
Swagatam says
Hello Patrick,
You can try the following basic op amp tester circuit:
https://www.homemade-circuits.com/wp-content/uploads/2022/11/op-amp-tester-circuit.jpg
Moving the either pots up and down should cause the LEDs to change their status.
However I would rather suggest you to build a new power supply circuit. A good power supply can be built even without op amps, and simply by using ICs like LM338
Patrick says
Hello Swagatam,
Thank you for the op amp test circuit. I will put that onto a bread board now and try it out. I did do a search on your site for an op amp test circuit but nothing came up so thanks for finding that for me. Your assistance is always so helpful.
I will look into building a new power supply if I can’t repair this one.
Keep well,
Best regards
Patrick.
Swagatam says
No problem at all, hope you succeed with the project….wish you all the best!
Patrick says
Hello Swagatam,
I have breadboarded your op amp tester circuit and it works great so thank you for that. I have tested all of my TL081 amps and they all test out good so it seems that that is not where my problem is.
I have looked at a few circuits using an LM338 voltage rectifier and they are all very basic compared to my CC – CV power supply so I am going to hang in there for a while and see if I can’t restore my power supply. I can set the current output to as low as 200ma at any voltage up to 31 and this has proved so useful over the years that I going to try for a while to fix it.
Thanks again for all your help and suggestions so far. You are such a great help to us electronic hobbyists.
Keep well
Best regards
Patrick
Swagatam says
You are welcome Patrick,
Glad the circuit worked for you! The LM338 can be also configured for obtaining any desired CC, CV.
Nevertheless, I hope you are able to restore your existing power supply soon.
Patrick says
Hi Swagatam,
Your help and advice with my electronics fumbling has been invaluable and I sincerely hope that you are around for a long time to come to continue to help us electronic hobbyist’s.
On Aliexpress I found a 0-30 volt 3 amp power supply kit which looks almost identical to my Smartkit 1138 kit so I have ordered two of them with a view to replacing mine if I can’t repair it. There are also some good threads out there to help with de-bugging it and improvements if you have a problem with it. There is also a couple of youtube video’s on assembly and testing so it does seem to work alright.
So at least I now have a plan moving forward and I am hoping that it all turns out well.
So thanks again and stay well.
Best regards
Patrick
Swagatam says
Thank you Patrick,
I am always happy to help!
That sounds great! I truly hope you are able to configure and test the available kit correctly, and your requirement is fulfilled soon.
abdulkarim says
please give me your WhatsApp number so that me send picture of construction
Swagatam says
You can upload the pictures to any free image hosting site and give me the links here, I will check it.
abdulkarim says
sir I used 2k resistor instead 1k they has problem
Swagatam says
Please show me the circuit, only then I can say!
abdulkarim says
sir please I did not have this step up transformer me can having radio 5 terminal transformer so how can I make simple
220v an bigger higher power an frequency
Swagatam says
The output power will depend on the power of the transformer. So if the power of the transformer is less then the output will be also less. The output voltage and power depends on the voltage and power specifications of the transformer.
abdulkarim says
sir how are you I can construction modified sine wave inverter but I did not have diode 1n4148 I can use 1n4007 remember I used radio transformer so the output voltage is 36v so how to increase the power voltage and frequency thanks you
Swagatam says
Hello abdulkarim,
1N4007 can be used instead of 1N4148. You must use a standard 220V step-down transformer for an inverter, a radio output transformer will produce very low output power.
parneet kaur says
Hello,
I have 60plus Meanwell SMPS to repair, could you help by taking this job under you. Please share your contact details and in which City you based in?
Swagatam says
Hi,
I am so sorry, I won’t be able to take this job since I am already too busy with other job assignments.
Fabrizio Ricciarelli says
Hallo Swagatam, my vivid compliments for your work and your availability.
Like many your readers I’m an electronic hobbyst and my field of interest is the resonance. Since a long time I’m looking for a circuit based on the 555 chip (CMOS) to produce a near-perfect square wave with a fixed 50% duty cicle but, unfortunately, there are none out there able to satisfy my needs so I thought of you.
These are the wanted characteristics:
– ultra-low power-draw (that’s why I specified above the “CMOS”), preferably in the order of the micro-amps for the oscillation circuit per se;
– able to generate a PWM with a variable output current (5-100 mA) and a variable frequency (20kHz-250kHz);
– the output PWM has to be totally insulated from the 555 (no back-emf spikes allowed to be returned to the chip) OR the output must have a very high impedance
– the input voltage of the circuit should stay in the range of 5-15 and the output voltage has to match the input voltage.
That’s it.
Of course I tried some configurations by myself, getting inspired by many schematics on the web so, for example, to insulate the 555’s pin 3 (output pin) from the external resonating circuit (a stupid LC couple), I put a pulse transformer (those micro guys used in some arrangements between the mosfet’s drivers and the mosfets) but this resulted in a big mess of unwanted harmonics so I gave up.
I have a friend, in Tamil (India) which is a retired electronic engineer and he wasn’t able to figure out how to solve the back-emf spikes without affect the resonance of the external LC (which has to remain “stable” and produce as high voltage as possible) and avoid the return of the high voltage to the 555 chip.
One curious thing: my arbitrary frequency generator (a cheap chinese box full of functions) is able to withstand even to 2 kilovolts of back-emf spikes without any issue (wtf…)
Any suggestion will be much appreciated.
If needed, for further details for example, feel free to come in contact directly through by the provided email address.
Thank you so much in advance and keep up the good job!
Fabrizio
Swagatam says
Thank you Fabrizio,
You can perhaps try the following design for the 555 PWM generator. The frequency is obviously determined by the values of R1, R2, and C3.
You can a see zener diode across the supply lines, you can beef up this zener diode with capacitors ranging from 0.1uF to 1000uF. These will probably quite enough to ensure that spikes are appropriately neutralized before they can enter the IC 555.
And yes instead of 555 you must use a CMOS version 7555.
https://www.homemade-circuits.com/wp-content/uploads/2022/05/DC-lamp-dimmer.jpg
Fabrizio Ricciarelli says
Hallo SWAGATAM and thank you for your kind answer.
Is the following correct?
https://ibb.co/zJwD1VK
Are you sure that the pot will change ONLY the frequency leaving the duty cycle fixed at 50% ?
Fabrizio
Swagatam says
Hello Fabrizio, the link you sent is not opening in my computer! You can perhaps try uploading it to some other free image hosting site.
Arijit says
Hello sir,
How are you, I hope you are doing well. I’m designing a 12v 3Amp(36watt) CV & CC mode SMPS. Early I designed 12v,2A SMPS by following your circuits and tutorials which is working fine. So what changes are required to design 12v 3amp SMPS? please reply .
Thank you
Swagatam says
Hello Arijit.
Glad to know you could build the 12V 2 amp SMPS. Can you please show me the article link which you tried?
Arijit says
Sure Sir
https://www.homemade-circuits.com/12v-2-amp-smps-circuit/amp/
Swagatam says
Thanks Arijit!
You can try using bifilar wire winding for the secondary side to increase its current capacity. Bifilar means using many thin wires in parallel and then winding them together to create a thicker winding.
Peter Gibas says
Hello Blogthor
I am very interested in the 3 phase inverter, which provides 3 staggered pulses as output. The pulses should have the fixed starting point as described, but the pulse width should be variable. This would be feasible with the NE555.
In general, my question is: can I buy a ready-made inverter? (with variable pulse lengths)
Greetings from Bavaria Germany
Swagatam says
Hello Peter,
Sorry, we do not sell ready-made inverters from this site. You can probably get one from online sites like amazon.
Bob Lucas says
First, let me acknowledge how appreciative I am for all the circuits and explanations you share. I find them extremely useful. Thank you!
Currently I am working on a hen house door opener for a son-in-law. I have a working circuit that includes an arduino nano and an LDR light sensor that will open the door in the morning and close it at night. I can’t employ your design for a hen house door opener that uses the limit switches. The current circuit works but it it drained the battery in one day. (That’s what you get when you use a ‘retired’ battery!). It also has an h-bridge board that has an LED on it. I measure 0.053 A quiescent current and 0.353 when the linear actuator is operating (this is without a door attached) so it would be more under load.
I am instead looking at the h-bridge with an arduino circuit you have posted. But without the arduino. Instead, I want to employ two comparator circuits (using the LM393). On one comparator the reference voltage (Between a 25k and 50k resistor) will be on the inverting input on one comparator and on the non-inverting input of the other comparator. The outputs of the two comparators should be opposite. I will add a 20k pullup resistor for each and these will be the inputs (like pins 9 and 10 from the arduino) to the NAND gates in your circuit. I am trying to keep current draw really low because really, it only operates twice a day at dawn and nightfall! The LDR is in a voltage divider with a 100k potentiometer that can be tuned to the right light conditions. If night or day conditions could trigger the whole circuit off until needed that would extraordinary but I have no idea how to do something like that.
I have the circuit drawn out in kicad, which I can provide, Basically I am wondering if I can replace the arduino outputs with two outputs from the LM393 comparator and if this seems reasonable.
I am just a hobbyist who got started with some circuits to add some interest to my model railroad. Now electronics might be my main hobby!
I appreciate any comments you might have.
Thanks!
Swagatam says
Thank you for your detailed explanation. However it is not easy to understand the schematic without seeing it. You can upload the schematic to any free image hosting site and send the link here, I will try to figure it out.
Bob Lucas says
Thanks for your reply. I don’t use any free image hosting sites, but I do management and support for a website, so I’ve uploaded a pdf there. Here is the link: https://sso.cirrealty.ca/ActuatorCircuit.pdf
You will see a DPDT switch in there. That is so I switch the outputs from the comparators which should cause output to the linear actuator to flip as well (Open if closed and close if opened).
Swagatam says
Hi, the link you shared is not opening in my computer….it is showing “this site can’t be reached”
Bob Lucas says
I forgot I can do this with dropbox.
https://www.homemade-circuits.com/wp-content/uploads/2022/10/motor-control-circuit-with-LDR.jpg
This should work!
Swagatam says
Yes it looks this would work, but simulating in mind can have flaws…only a real testing will prove if this will actually work or not.
cindy says
Hi Sir Swag, do you have a simple circuit that control any liquids from overflow that i can use in a bottle of different sizes, such as soda bottle?
what i means is a circuit that control liquid overflow filling nozle?….
Swagatam says
Hi Cindy, a fluid controller can be designed using a transistor and a relay but how will you insert or accommodate the sensing probes on the nozzle?
cindy says
I will use a nozzle that is small enough that i can insert inside of a soda lid bottle but big enough to accommodate the two wire or sensing probes inside it!…. or do you have any better idea Sir?….. im planning to sell bottled cooking oil in different sizes of bottle/canister, but i want to speed the process by filling 6’s or a dozen at a time!…
Swagatam says
If it is oil, then I am not sure if my circuit would work? Because I don’t think oil conducts electricity efficiently. Instead you can use a timer based solenoid tap whose ON time can be calculated to ensure that the timer switches off the solenoid tap after an approximate period which is enough to fill the canister to the required level
cindy says
thanks for the info Sir, do you have that kind of simple and adjustable timer circuit that drives atleast 6″s solenoid valves simultaneously?…. and if you please, may i have also a circuit for the water filler nozzle?… thanks a lot Sir!
Swagatam says
For the timer you can use the last circuit from the following article:
https://www.homemade-circuits.com/how-to-make-simple-timer-circuit-using/
For the water sensor you can try the first circuit from the following article:
Municipal Water Supply Sensor Controller Circuit
cindy says
Hi Sir, i have other query, do you have any circuit that control a motor thru a relay by way of weight of an object?… i mean the relay will turn-off once the weight of an item reach a particular weight or kilo?….. the process must be manual turn-on and automatic turn-off, and the particular weight/kilo must be adjustable accordingly!… thanks you very much!
Swagatam says
Hi Cindy,
You can try the 741 circuit from this article. You can connect a transistor relay driver stage after the LED for integrating a a relay system. The 680 ohms will need to be then replaced with a 10K resistor.
https://www.homemade-circuits.com/force-sensing-resistor-explained/
Jack Shubert says
Hello, I am looking for a circuit diagram for a type of low frequency adjustable flip flop square wave output that crosses over polarity relative to a fixed point. perhaps using 555’s with a +12volt and a -12 volt DC power supply. The purpose is to drive a small low current 12 VDC motor that is a part of a small linear actuator. I wish to control the distance of travel and the time of the actuator without the need for mechanical limit switches or a DPDT polarity switch. The desired repetition rate would be in the seconds. Thank you for your help. Jack
Swagatam says
Hi, sorry I can’t figure out how a 555 IC astable can be configured using a dual supply and with an output that would cross over polarity relative to a fixed point??
Dinesh Modi says
I want to make Solar Stud Light,
Can you supply Assembled PCB size 40x20x8 mm (Length, width & Thickness including Components) with 6 Nos. LED dia 3 mm
or can you guide to whom we can if you not,
our all moulds are ready only electronics required
Swag says
Really sorry, I cannot supply assembled kits and I have nobody who might do this for you…
Arijit Mohanty says
Hello sir
I want to design an automatic power reset circuit for my GSM module power supply unit. So that I can reset my main power supply for a couple of minutes when there is no Tx,Rx signal from my GSM module, and when the GSM starts giving data the power supply will return to its initial ON stage, because when I manually reset the power supply the GSM module starts giving data across Tx & Rx. If it is possible by using a 555 timer then please help me with my project.
Swagatam says
Hello Arijit,
I am not sure how your power supply can be reset without seeing the power supply diagram. By resetting do you mean switching OFF the power supply.
Arijit Mohanty says
Yes sir
In my circuit I’ve used MP1584 buck converter for power supply. I need to reset the power supply by applying logic low signal at the enable pin of buck converter by providing 0v or voltage less than it’s threshold voltage limit. So that the power circuit can reset perfectly and give fresh data across GSM Tx&Rx.(if there is data across tx/rx then no reset,if no data across tx/rx for a minute then auto reset.)
Swagatam says
OK, so if there’s no data for a minute, then the power supply is reset. Resetting means the power supply is fed with a logic zero only for a second (momentarily), right?? meaning each time the data stops for a minute, the power gets a quick 0V logic ON/OFF signal for resetting.
When the power supply is reset the GSM is switched OFF and ON and the GSM begins supplying fresh data??
I hope I have understood it correctly.
Arijit Mohanty says
Yes sir, You exactly got my point what i was trying to explain regarding my issue.I need to reset the power supply for a moment so that all the peripheral can restart.
Thank you
Swagatam says
Arijit,
You can try the following circuit:
https://www.homemade-circuits.com/wp-content/uploads/2022/09/monostable-555-circuit-activated-with-date-input.png
Arijit Mohanty says
Thank you, sir. I’ll share my feedback after testing this circuit.
Swagatam says
Sure, no problem…
Scott Anderson says
Looking for an AC Induction Motor Speed Controller circuit:
120v
0 RPM to full motor speed.
Not a “dimmer” type circuit, I believe the type that will not harm the motor uses triodes, Pulse Width Modulation … etc.
Thanks in advance
Swagatam says
I have a related article on induction motor speed control, you can find the link here:
https://www.homemade-circuits.com/3-phase-induction-motor-speed/
Dennis E Jann says
Other than social media, how can I “join” this group?
How can I download some of your teachings, pics and schematics?
Swagatam says
You can join us simply by commenting under the articles, we will make sure they are answered. Unfortunately there’s no download option for downloading the articles.
Merdom says
Hello Swagatam. First of all thank you for posting all sorts of very useable circuits especially ckts for LED drivers. I’m a hobbyist too including automotive and I would like to see if you can design a circuit for car test light. But this test light has the capability to display the intensity of the voltage ie, 0-12V using maybe 4 or 8 led’s. Something that will tell me if the voltage its getting is a full 12v or half voltage 6v., or lesser. I’ve looked everywhere and the only closest ckt I found was light chaser like the knight rider. I’m sure you already have an idea of the ckt since you are the master on the field. Thank you again!
Swagatam says
Thank you Merdom, you can perhaps try the following circuit:
https://www.homemade-circuits.com/wp-content/uploads/2013/08/10stepbatteryindicatorcircuit.png
Adjust the 10K preset so that all the 10 LEDs are illuminated when the circuit is connected to a 12V battery or 12V supply DC.
Tym says
Hi Sir,
I’m a hobbyist, thanks a lot for the circuit and help recently you gave me.
Can I ask you to recommend some good basic electronics books and websites, I want to learn from the basics to engineering level, I know I should go to electronic engineering colleges but my bad nervous system does not allow me, so the books and the web are the only sources for me. But this is just my hobby and not my carrier.
Thank you so much.
Swagatam says
I am glad to help you Tym.
Unfortunately I do not have an article which presents a step by step tutorial for the newcomers.
But you can learn from this website by asking questions to me and I will guide you with the procedures.
You can start with transistors first, and a god first project could be a relay driver circuit as explained in the following article:
Transistor Relay Driver Circuit with Formula and Calculations
Next, I will tell you how to replace the relay with other loads like an LED
Tym says
Thanks a lot Sir, I will learn from your links but I can’t study at a regular time because of my home works and my bad health, so should i contact to your facebook messenger to be convenient?because it is busy to find old comments and they are always growing in this page. And I want to ask another two questions,
1. What will be your advice to learn from below link, is it worth for my times and effort? because some are just theory and/or give no idea for pratical.
https://www.allaboutcircuits.com/textbook/
2. Can you recommend me good basic ebooks or pdf, etc.? because I really want to learn step by step from the basic, please help me.
Swagatam says
You are welcome Tym,
Unfortunately answering consistently on facebook will be difficult for me since I am mostly busy answering to blog comments.
The content on the link is good but it might take many years for you to learn them and finally build a circuit, so we should go the opposite way. That is build small circuits directly by learning the bare basics.
If you search online “learn electronics circuits basics” then probably you will come across many good resources which you can refer to, but again these are very elaborate and might require many years of learning to master them. So it is always good to go the practical way, and learn and troubleshoot as you make mistakes, which can be a lot of fun.
Tym says
OK Sir, so I will learn from this place.
I like your practical way and I also don’t want to be long many years just by reading but I’m reading basic books available in my Mother Language though they are not that good, so I have to Google some good resources for reference and in case of need.
So, I will report after studying the first transistor relay driver circuit.
Thanks a lot.
Swagatam says
Sure, no problem.
Feel free to contact if you have any further question or doubts….. I will try to solve it for you.
Chris says
Hello, Swagatam. I built an inverter using the IC sg3524, it worked pretty well but I’m having issues trying to build a filter for the inverter, because it geneates a loud humming sound when used with some loads like a fan for instance. I tried using a 1.5uf 400v capacitor in parallel with the output of the inverter, it helped a bit but became less effective as I increased the load on the inverter. Please help me out with a more effective filter circuit.
2. Could a filter be added around the Pin 11 and 14 of the sg3524? (That is before the MOSFETs gate).
If possible I’d also love a circuit of such a filter.
If any of the above ideas would work perfectly I’ll use them. Help me out. Thank you.
Swagatam says
Hello Chris,
Unfortunately an LC or capacitive filter cannot be added on the MOSFET side of the inverter, it can be added only on the output side of the transformer. You can try increasing the capacitor value to 3uF/400V and check the response. However increasing the capacitor value will also mean some power getting wasted through the capacitor.
Marcelo Russi says
Hi Swagatam, I’m developing an electronic mouse trap. I tried to use one of your circuits, from the alcohol dispenser, but I didn’t get success because I don’t have much experience with circuits like that. I only use arduinos and so. I would like to use an 18650 battery, an ldr that triggers a relay for 1 minute and then turns off. The relay must drive a high voltage generator purchased off-the-shelf on ebay, using the same battery. After that, a flashing LED is on to warn that a shot has been fired. As the battery produces from 3.3v to 4.2v I can’t use the 555. I understand that using a simple circuit the battery consumption in stand by would be minimal. I would be very grateful if you could help me.
Swagatam says
Hi Marcelo,
When a light beam on an LDR is blocked by the by rat, it triggers ON a relay for 1 minute, this will be the basic working of the circuit. However this cannot be perfectly built using transistors. You will have to use the IC 555 for this. You can use the CMOS version of the IC 555 which is 7555, and these can work with 3V also. The relay will also need to be rated at 3V
Hennie says
Hi Swagatam, I have a request from a customer to build this circuit for him. Please help me with the function of the 1N4148 diode connected in reverse from pin 2& 6 (connected together) on NE 555 ic to VCC.
I assume this is to discharge the capacitor? Not sure though. Your kind assistance will be appreciated.
I have the circuit diagram ,but not sure where to upload it.
Thank you.
Hennie.
Swagatam says
You are right Hennie, those diodes help to determine whether the capacitor needs to charge faster or discharge faster depending on the setting of the associated potentiometer. This in turn decides how the output pulse widths are adjusted.
You can find a few of these circuits explained in the following article:
https://www.homemade-circuits.com/ic-555-oscillator-alarm-and-siren-circuits/
Omotoso Daniel says
My name is Daniel, am a beginner and I have gain a lot from this site. You are doing great thank you.
Mehtab says
Dear Sir,
Kindly help us on the design of smps based electrofusion welding machine.
Output: 40-45V DC
Current: 60A max
Swagatam says
Sorry, Mehtab, I do not have a 60 amp SMPS circuit with me at this moment.
Malc says
Following your previous help with my “Touch switch” circuit, I built up the circuit using one of the 4050 ICs on a breadboard using one of the gates as per your diagram and it worked OK. However when the touch pads were merely touched they did not operate, the fingers had to be wet to switch the gate. This is not a problem, I used switches instead and all was well. I did find that when the circuit was switched off then on again the LED lit, this was useful as it saved me having to use separate switches to light up all LEDs, powering up the circuit would light up all LEDs and I could cancel the required LEDs with their individual switches, great, that would do what I wanted.
Before building a permanent circuit I decided to add another LED to one of the other gates using the same capacitor/ resistor / switch configuration as the previous gate. The on / off switches worked well as before, but this time when the circuit is powered up the LEDs do not always light up. Sometimes they do and sometimes they don’t, the results are very hit & miss. A time delay before powering up again seems to help – sometimes. I have also tried switching the +Volt and the -V rails individually and again, hit & miss results. I am concerned that introducing more gates will only add to the problem. Can you suggest a reason / remedy for this ?
Swagatam says
The circuit is actually quite basic so we cannot expect too much from it, there may be some downsides in the design which can be difficult to rectify.
You can perhaps try adding a resistor and capacitor network to the positive supply line of the IC. Meaning, you can add a 220 ohm resistor in series with the positive supply line and add a 470uF capacitor right across +/- terminals of the IC, this will allow a slow start to the DC supply input and hopefully help to eliminate the hit or miss issue.
You can also experiment with C1 and see if that helps to correct the issue
Fabio says
Hello,
I have a question to this post https://www.homemade-circuits.com/tachometer-using-arduino/.
I want to build a tachometer but I don’t have an arduino, instead I have my own type of card with an Atmega16 and I’m programming in Microchip Studio. The main problem is, that I can’t use the function millis(), could you show me how I should programm the timer of the Atmega16 to get the same result?
Thanks for your help.
Fabio
Swagatam says
Sorry, my microcontroller knowledge is not good, so it is difficult for me to answer the question.
Len says
I am just learning about uni-junction transistors. With all of the information that I have read about them, I have not seen anything about whether there are n-type and p-type devices. For example, would one type be controlled by a negative or positive input voltage if there are the two types of devices. Len.
Swagatam says
Unijunction transistors work like oscillators, they do not have N-type or P-type classification.
You can see some example circuits in the following article:
10 Simple Unijunction Transistor (UJT) Circuits Explained
Prashant says
Hello sir my name is prashant i read your blog very nice electronic project is my hobby. I like to try new projects. I visited your site for the first time today and I really like your site because it has a lot of knowledge. So far I have not seen this much knowledge on any other site or YouTube. I need your help. I am making a bi color 5 mm display board. In which 218 bulbs have been used. But I can’t find the 218 LED bulb circuit anywhere, most places have the same bulb circuit as the forty-fifty, but on your site I found it. Information has been received. But still I have a request please send me a circuit diagram on my email that how can I make the circuit I have all the bulbs connected in series. I have learned a lot about transformer less circuit but the question is how to provide such a every bulb current, voltage. From your blog I understand that it is easy to make a circuit using both series and parellal but still I need more proper information about it. Bi- color most of the videos on YouTube say two volts but from yours I understand that it actually has 3.3 volts. Please reply soon as I want to make this before the upcoming Ganpati Pooja. If I want to make some changes in that series to parrelal or parrelal to series, another one but tell me I will do it. Thank you for your information, Guidence and help.
Swagatam says
Thank you Prashant, Glad you liked this site!
I will surely help.
But first I want to know the LED specifications. You said it is bi-color, so does the LEDs have 3 pin? Also what is the current specifications of the LEDs, are they 20 mA rated or higher??
Since each LED must get 3.3 V for proper illumination, that means if you connect 218 in series would require 218 x 3.3 = 719 volts which looks impossible to get.
The maximum voltage that can we can derive from a low current AC supply is 310V, so the LEDs will need to be configured in strings, each string having 310 / 3.3 = 93 LEDs. Keeping some margin, we can use strings of 90 LEDs each.
I will design it for you once I get the full specifications of the LEDs.
Mathew says
Hello, based on the name – where are you based TN or Kerala?
Do you build industrial power solutions – looking for a single phase 110V to three phases 208V converter – current can be < 3 amps.
Thanks
Mathew
Swagatam says
Hello, I am located in Mumbai. Sorry, due to lack of time it can be difficult for me to accept external assignments.
genie225 says
Hello, I have finally fix my ATX power power supply over current protection problem. Can you help with a circuit. I want to use a voltage regulator 7824 to convert the output 12v to 24v. But the 7824 don’t support more than. Is it possible to put 20 transistor 7824 in serie for a high current support, And include the TIP36 in the circuit with a current limiting circuit for the load. The load current increase when it getting hot I want to limit it to 20a because of the power supply.
Target: supply 24v with a high current and circuit protection (pwm) with a ATX power supply.
Thank you
Swagatam says
Hi, 7824 cannot be used to convert 12V to 24V.
Your question is not very clear so I am finding it difficult to understand.
Genie225 says
Hello,
I have convert 2 power supply atx ( Liteon Ps-5301-08HF and Dell F255E-00 ) to power 2 loads on 12v each PS. After 30mn the first off and 5mn latter the 2nd off. When I on it now without load it run but it off when I put load. How can I resolve this fault. Is anyway to reset the current protection.
The 12v current rating of the Liteon ps-5301-08HF is 19A max, 300watt and the 12 current rating of the dell ps- F255E-00 is 17A. I have not bypass the current protection and I use each PS separately. The load current is 15a his and increase when he getting hot.
Thank you to help me solve this.
Swagatam says
Sorry, it may be difficult to solve your problem, because it is related to the internal circuitry of the ATX which will need to be checked practically.
Tym says
Sorry, I forgot one thing, battery voltage is 4.2V when fully charged.
Swagatam says
You can try the transistorized current limiter version, as given in the previous link.
Tym says
Hi,
I’m searching for a constant current led driver circuit with good efficiency to drive parallel 10 pieces of 5730 LEDs at 700mA, LED forward voltage drop is around 3.2V, power source is a 1800mAh 18650 battery,
a TP4056 module(with battery protection) is used. I don’t like series resistor because of dimming after some minutes, and I can accept shorter running time. Can you help me please?
Swagatam says
Hi,
I have an article which explains a few constant current limiter circuits for LEDs. You can optimize one of them to match your requirements. Here’s the link:
2 Best Current Limiter Circuits Explained
Tym says
Hello, thanks a lot for the circuits.
I want to use transistor version but I don’t know which transistor part numbers to use for my low voltage input and for possible lowest power dissipation, and if possible I prefer mosfets for their efficiency.
Input voltage ≤ 4.2V (18650 battery)
Led Vf = 3.2V
Total Led current = 700mA
Can you help me please?
Swagatam says
MOSFET will not work with 4.2V, so you will have to use a BJT based current limiter circuit.
For T1 you can use TIP31, and for T2 you can use 2N2222
CARLOS MONTENEGRO says
I AM INTERESTED IN THE RF signal jammer circuit AND OTHER TYPES OF CIRCUITS FOR MAKING JAMMING DEVICES. DO YOU HAVE A COURSE OR BOOK THAT I CAN LEARN THIS? THANK YOU CARLOS
Swagatam says
I appreciate your interest and hope you succeed with the project, however I do not have a detailed course book for this at this moment.
Carlos Carrera says
Greetings!!
I need to reduce a variable input voltage from 9V to 60V to 3.3V.
The circuit will receive a pulse from 9V to 60V, this pulse will trigger a digital pin of the ESP32 which will make it perform a function.
Sir can you help me.
Thank you very much in advance!!
Swagatam says
Hi Carlos, are you looking for a 60 V to 3.3 V buck converter circuit?
DavidH says
Hi, I am looking for someone to design simple high efficient voltage regulator with ATX terminals.
input 12V PCIe 8 pin cable used for powering power hungry GPUs and convert it to Molex 4 pin connector with 12 & 5V…which can be used with any commercially available Molex extension or Molex/SATA adapter cables.
It is for a 100+ HDDs hobby server project. I do not want it for free, but I need electronic engineer hacker ready for challenge. So far, I have contacted at least 5 people…everybody says “no problem, send the details”, and never reply 😀
If you are interested, please contact me via email. I will send you all details/requirements.
thanks DavidH
Swagatam says
Hi, I am not sure about the pinouts of the cables that you are suggesting, however 12V and 5V regulators could be built using buck converters. Buck converter would be required because making 12V, and 5V regulators using linear ICs like 7812 and 7805 can cause a lot of heat dissipation and that wouldn’t be efficient.
DavidH says
Hi Swagatam, thanks for reply. I have full details in PDF, but I cannot find an engineering able to design it :o)
Is it possible to hire you, please?
Swagatam says
I am sorry David, that might not be possible due to lack of time. I can only help with general circuit ideas. Solving elaborate circuit queries can be difficult for me.
Malc says
Hi Swagalam,
Sorry, it’s Malc again. Re: my question on switching 9 outputs, I also intended to ask whether this would be easier / possible using an Arduino ? I have an Arduino Uno and a fair bit of compatible kit but not great when it comes to the code.
Swagatam says
Hi Malc,
For 9 LEDs, you will have to use 9 such gates using two ICs. Yes using Arduino may be possible but my Arduino knowledge is not good, so it will be difficult for me to solve it for you.
Malc says
Hi Swagatam, thanks again for your super fast reply. I will look into the possibilities of both ideas. I have access to the usual Arduino forums etc. so it should keep me out of mischief for a while. Thanks again for you input.
Swagatam says
It’s my pleasure Malc, all the best to you!
Malc says
I am trying to construct a touch switch circuit to switch 9 LEDs on and off independently. I have managed to switch a single LED on and off using a 555 IC connected as a touch on/off switch and this worked well. Obviously I could use 9 of the 555 ICs to achieve this but it seems a clumsy way of doing it. Is there an IC capable of switching 9 outputs independently, or perhaps doing the job with 2 ICs ? I would be grateful for you help / advice.
Swagatam says
That may be possible if two switches are allowed for each LED. One touch switch for ON and the other for OFF operation.
Here’s one simple design that you can try. A single gate from the IC 4050 has been used here. Each 4050 contains 6 such gates, therefore 6 LEDs could be operated independently using a single 4050 IC:
https://www.homemade-circuits.com/wp-content/uploads/2020/05/simple-flip-flop.jpg
Malc says
Many thanks for your prompt reply. Your suggestion looks good. I will certainly give it a try. Thanks again.
Malc
Swagatam says
Sure, No problem!
Hamoud says
I would like you to help me to design a circuit for controlling the speed of electric motor to use it driving car instead of fuel engine.
Swagatam says
What is the specifications of the motor?
Khalid says
Thank you very very much
Arthur Wright says
Hi. I am rebuilding a caravan in the UK and want to have a portable solar panel to support the various 12v equipment I’m having. My problem is finding the right sized solar panel. I will be having a few 12v LED lights, a 1000W inverter, a small 12v/240v tv, a 12v fridge and some USB sockets for phone/lap top charging. I tried working out what the load would be on the LED’s but I don’t have a degree in electronics to understand what is being said online. Any help would be greatly appreciated. Thank you in advance for this great service you are offering to know-nothings like me!
Swagatam says
Hi,thanks for your question! I understand your requirement, however for calculating the solar panel specifications we would first require the current and voltage specifications of the various loads. So, for example for the 12V LED we would need to know the current spec of the lEDs, then for the 1000 watt inverter we would need to know the DC voltage which the inverter would be using. Similarly, we would require the current specifications of the TV and the fridge.
Once we have the voltage and the current specifications of the loads we can then multiply the two values to get the wattages of the respective loads, and then add them together to evaluate the approximate specifications of the solar panel.
Arthur Wright says
Wow, thank you for such a speedy response! I think I might be able to finish the calculation off once I understand how to determine what the Wattage of the LED’s will be, which is the confusing bit. I will be having one set of 4 x 12v LED’s with a power rating of 0.4W and a current draw of 0.03Amp per light. I will also be having one pair of the same, together with 3 individually controlled light fittings. As you so very kindly asked, I will also be having a 12v/240v CRX80 Dometic Fridge rated at 48W with a rated current of 5.6A and 0.56A at 240v. The DC voltage for the inverter will be 12v. The 12v TV/DVD player will be approximately 36W with a power supply of DC 12v 3A. Also I was thinking I would need 2 leisure batteries…. Hope this is all you need. Regards..
Swagatam says
12V LED wattage will be
0.4 x 4 = 1.6 watts
0.4 x 2 = 0.8 watts
Fridge is 12V 48 watts
Inverter is 12V 1000 watts
TV is 12V 36 watt
Total wattage becomes = 1086 watts or simply 1100 watts
For all these loads working together, you will require a solar panel with an approximate specification of 15V, 1200 watts
Arthur Wright says
Oh! That would be impossible for me as I wanted to hook up a portable solar panel and thought a 100Watt one would do. Inverters are used to convert DC to AC current, correct? If so, to run something like a microwave, I would need a 1200W solar panel, which is impractical with a caravan, so how do people do that? Sorry to go on, but the more I find out, the less I know…
Swagatam says
For operating a 1200 watt load you will have to have a 1200 watt power source, right? There’s no other alternative for this. The power has to come from somewhere, in your case it is a solar panel…so the panel has to be rated at 1200 watts. It is indeed impractical to run a 1200 watt load in a caravan.
Arthur Wright says
Thank you for your help. This is such a difficult area for me to understand, having no knowledge in electrics, but you saved my bacon! You are a real gem!
Swagatam says
It’s my pleasure Arthur. Glad to help!
A. Selnik says
I have a “Kidde” detector in my living room and it takes batteries. There is a “First Alert” smoke detector in the bedroom. It does not take batteries. Instead it is connected to wiring in the wall. It gets its electrical power from the house current. After it detects a fire it sends a signal through the wire to a phone box in the basement and the fire department is contacted. Are either of these alarms an ultrasonic alarm? Thank You.
Swagatam says
It can be difficult to tell without practically seeing the device. It can be based on an ultrasonic sensor or maybe a standard smoke/gas sensor
Tun says
Good evening sir,
Sir you have deleted a post based on hho gas generator, what happened sir?, and can I have the schematic or the pdf for the project?
Swagatam says
Hi Tun, actually it is dangerous to generate HHO gas at home, that is why I deleted that post. You can check the following post and use the set up to generate the HHO gas using 220V DC. But remember this set up is also dangerous and you would be doing it at your own risk:
How to Generate Pure Oxygen and Hydrogen at Home
karl says
Thank you, Sir. Your reply was corroborating what I was thinking in my head. I cut my teeth in the days of vacuum tubes, but obviously made the transition to solid state devices many decades ago.
I was recently monkeying around with a circuit for a Unipolar Stepper Motor controller, and came upon the fact that since the ends of the four coils were tied to IGFETs, the two ‘high’ side leads had to go to a ‘switch’ to shut off the current when the motor was not being energized. The obvious solution was to use a high-gain PNP power transistor (TIP12x) as the source, but then I was thinking about making sure that this transistor was guaranteed to be cut-off when the motor wasn’t being powered. In this case, it seemed logical to ensure that the transistor was biased off, especially since the motor is part of a machine, and the mechanics & control of the machine cause the overall electrical environment to be somewhat noisy. I just want assurance that I was thinking along the correct pathway by using a cut-off resistor. As I previously stated, I saw many instances where a PNP transistor was used in a current source, and there was no bias resistor included. This disturbed my logical thinking.
So, again ….. THANK YOU for your reply. There is no need now for you to reply to me. I appreciate your feedback.
karl t.
Swagatam says
Thank you Karl, for your detailed explanation, I appreciate it a lot. All the best to you.
Amit says
Are you available for freelance consulting?
Swagatam says
I am available through comments on this blog. You can ask your questions, if possible I will try to solve it for you.
Val says
Hi Swagatham
In one of your blogs showing the circuit for proximity sensors using IC 741 what is the value of the pot used and which is the transmitter IR LED and which is the Receiver led it’s only mentioned as IR led and Photodiode led, I’m all confused which is which
I have two IR LEDS one is dark colour (Receiver)and one is clear (emitter)
Appreciate a reply along with the link for this blog
I tried out this circuit with a 10k pot but it does not activate the relay with motion in front of the IR LEDS
Swagatam says
Hi Val,
I have updated the diagram with the relay and all the other details in the following post:
https://www.homemade-circuits.com/simple-proximity-sensor-circuit/
Marc Soldner says
Hi, I was looking over your SG3525 circuits. Nice work. I was thinking about building a Peaking Power system to augment a portable generator set output with a solar-battery system, during short high-power demand periods. To connect the inverter to an already operating generator set there are three issues to consider, Voltage, Frequency and Phase. Setting voltage first and then frequency second is not too challenging using the SG3525 invertor with some smart adaptations (Arduino). Comparing the phase for synchronization and relay lock the systems together is a bit more interesting. Have you done anything like this, or have any ideas where to point me for study.
Swagatam says
Hi, thank you for liking my work, appreciate it.
However the question you have asked looks too complex for me, I haven’t yet done any work on this concept.
Marc Soldner says
Thanks for your reply. If I have any luck I will share it with you.
Swagatam says
Sure, no problem!
karl says
Thank you, sir, for your corroborating reply. The reason I asked this question is because in many general load-switching circuits that I’ve seen, some show a ‘cut-off’ bias resistor going from a positive supply rail to the base of a PNP transistor, acting as a switch. Other times not. So, I was wondering whether this was laziness, frugality, forgetfulness, or just plainly unnecessary. In biased circuits where there is an AC component for amplification or switching, it’s understandable to set up the transistor as an emitter-follower to allow for the full excursion of the signal, but with the simple off-on scenario, I wasn’t sure.
Finally, would you suggest a typical % range of values, or just a ‘hard’ range ….. let’s say for a typical 2N3906 class, and maybe either a 5v or 12v pos. rail, would you recommend 100K ohms, more or less?
Thanks again.
karl
Swagatam says
Thank you karl!
Even if you don’t connect the base emitter resistor still the transistor will remain cut off during the absence of a base signal. However, without the base emitter resistor the transistor base could be floating and attract stray signals from the atmosphere and might go into conduction mode…that is why it sometimes becomes crucial to add the base emitter resistor just to make sure the transistor remains perfectly cut off while there’s no input signal at its base. Typically any value above 100K will work fine, although it depends on the existing base transistor with which this base/emitter resistor forms a resistive divider.
Val says
Hi Swagatham
I’ve sent you three diagrams based on your circuits and discussions to you email as I don’t have multimedia and I request you to see if they are ok and will work out
Also need the values of the components used in the first transmitter circuit and which of the two is better
Thanks & all the best
Swagatam says
Hi Val,
I have answered to all your previous questions, you can check them out
karl says
Simple question, maybe?
When using a PNP transistor in a source mode, does it make sense to put a large value resistor from Vcc to the base as a ‘cut-off’ source,
or is this just a waste of money by adding an unnecessary component to a typical circuit?
Swagatam says
Adding a capacitor from positive supply to the base of a PNP transistor will not cut off the transistor, it will create a momentary switch ON/OFF delay for the transistor
karl says
Mr. Swagatam,
My question was not about putting a capacitor between the Emitter & base of a PNP transistor; it was about putting a high value resistor between the base & emitter of a PNP transistor when the transistor is being used as a high side switch. The emitter is connected to the voltage rail, the collector connected to a load (relay coil, LED, etc.), and the base is connected to an active low signal through a base current-limiting resistor.
thank you.
Swagatam says
I am sorry, I misread your comment. Actually, yes it is a good idea to keep a high value resistor between base/emitter of a transistor regardless of whether it is a PNP or an NPN. It ensures that the base of the transistor is never floating in the absence of a base signal.
Val says
How do I insert the circuit in this post
Val says
Hi Swagatham
I have this sensorTSOP 1738 and tried it out with a remote control the led is normally ON and when I press any button on the remote control the led goes off.
What transmitter circuit should I use so that when interrupted it turns the led off and instead of the led can it activate a relay circuit that you can suggest
Swagatam says
Sorry Val for all the trouble, you cannot inert the images in this website….I was actually suggested you to post your comments with images on my social media accounts such as facebook, facebook-page, Instagram etc, whose links are given above.
I hope you will not mind this.
Val says
Thanks Swagatham for your reply
I don’t have any of the media like Facebook etc
I’ve seen a post of a similar circuit I shall try it but I want to know what transmitter circuit should I use to keep it in a mode that when the signal is interrupted it should trigger the relay on
The transmitter and receiver should be about 6 to 8 feet apart
Marcel says
Please I want to know how to write a code using assembly language programming that will get an input from ultrasonic sensor and send it’s output to a gsm module and 16X2 LCD.
Swagatam says
I wish I could help you, however my programming knowledge itself is not good, therefore it would be difficult for me to help you in this regard
Marcel says
Okay Sir…. Thank you.
Swagatam says
Can you please provide the exact link of the article that you are referring to?
Ahmed Amen says
Hi! Mr. Swagatam
OK, I see your concern that you are busy.
I am very thankful that you allow me to use your design. And I also very pleased for your deep kindness that you are also interested to help me in technical matters.I end u some question on quora hope u could help me
Swagatam says
Thank you Ahmed, I am always glad to help. Can you please repeat the question which you asked on Quora, if it’s possible I will try to help.
Ahmed Amen says
Can I use that one ☝️ DC Adapter (12 v 2A )to charge 2 of those batteries (6 v 7.0AH/20HR) connected together? If yes how long time would it take to full charged?
Swagatam says
If you connect the two 6V batteries in series then it will require 14V input DC for charging them, the 12V adapter cannot be used for charging the two 6V batteries in series.
Ahmed Amen says
Thank U For Your Kindness So What If I Separate Them And Try To Charge Them One By One Would It Work To Conect The 12 V Dc Adapter To a One 6 V Baterry . I Have Another Question I Had Some Contents Parts Which I Dont Know What Is It And What Is It Used Fore But I Dont Know How To Show U Its Pictures , Can U Tell Me How To Show U It
Ahmed Amen says
I sent u it’s pix on messages on Twitter
Hope u tell me more about them
Swagatam says
Yes, you can use the 12V to charge the 6V batteries separately through a LM317 voltage regulator power supply. Just make sure to adjust the output voltage of the 317 to exactly 7V, and then apply this 7V to your 6V battery.
I checked the images that you sent me on twitter account….however unfortunately I could not figure them out, they look like they are some kind of varistors or MOVs.
Swagatam says
Thank you for your advice. I have already provided sufficient warnings in the article regarding the dangers of using capacitive non isolated power supply, and I have also suggested that the circuit must be properly insulated while using.
By the way none of the string light circuits I have seen in the market today use isolated DC, they all use AC mains and are thoroughly insulated to ensure the necessary safety to the users.
Cal Tiger says
Hi, your article on Smartcars and Arduiono is very valuable. I am a former Electronics Engineer working on a proof of concept for smartphone operated door and ignition locks. I have sent you a FB connect request. Pls add me on FB.
Thanks.
Swagatam says
Hi, Thanks, Glad to know about you…I have accepted your friends request.
Dawit says
Hi! Mr. Swagatam
OK, I see your concern that you are busy.
I am very thankful that you allow me to use your design. And I also very pleased for your deep kindness that you are also interested to help me in technical matters.
I am preparing things and thank you again for your great wish that I will be success.
with Best Regards!!
Dawit
Swagatam says
You are most welcome Dawit…
Claudio says
Dear Swag, I’m Claudio… ;-)… excuse me… could you imagine other features of inductor?… furthermore… someone thinks that the duty cycle should be in microsec order… what do you think about a ne555 flip-flop with 2n3055 to bear the high extracurrent? Bye
Swagatam says
Hi Claudio 😉 Could you please tell me which schematic or concept are you referring to? I’ll try to answer to your query…
Claudio says
Hi Swag..;-)… I’m sorry… I’m referring to a simple schematic about the «cold electricity»… in the free energy section…
Swagatam says
OK got it, yes you can try a IC 555 based oscillator for creating the collapsing the magnetic field, and subsequently cold electricity, however I am not sure what frequency would be ideal for this operation…
Claudio says
…ok.. but for the inductor?… its features is very vague… ;-(… can u help us? Thanx
Swagatam says
I can help only once I test these concepts practically, I may do it sometime soon and will update the results here for sure…
Dawit says
Hi! Mr. Swagatam
I am Dawit and Electrical Engineer
I have been working in different industries by giving maintenance for different electrical control system. Now when I come with your site and see your creative works I realy appreciated you and I have been myself ignited to such works and turn them to a business in home based. of course, I have not yet facilities for such production. What do you suggest me to have, and toward degree would you cooperate me to such manufacturing and turn them to business if it is your interest to work with your design works. In our country, Ethiopia, a lot of your works have business. for example home air ionizer would have a lot business In our gas polluted town Addis Ababa.
Thank you in advance for your attention
Dawit
dave4me60@gmail.com
I
Swagatam says
Hi Dawit,
I appreciate your offer and enthusiasm, you can feel free to use my designs for manufacturing and doing business in your country, however I personally wouldn’t be able to cooperate in this venture with you, because I am already too busy with many assignments here, so getting involved with any external business would be difficult.
Anyway I Wish you all the success! Let me know if you need any help regarding any technical matters, I’ll be happy to help!
ERNTEC says
Dear Swag,
Please help design for me an instructable UNIVERSAL SMPS for High Power Amplifier voltage ranging from +/- 50v to +/-100v Dc.
Thanks.
Swagatam says
Dear Erntec, I am sorry I am not good with designing SMPS circuits, therefore presently it won’t be possible for me to help you in this regard..
Nkwenti says
Thank you very much for replying sir.
Is ok if you can give me the digital clock without the date, But will the time be set to work both French and English time?
As for the link you sent, thanks very much but now my question is, if i assemble the circuit, can it be connected to the CDI as it is then the car speed be set to certain frequency? if yes then good, it will even be good because i can use one of the leds to energize a transistor as a switch then start to think of what to do next…
i look forward to read from you and thanks a lot.
Nkwenti.
Swagatam says
Hi Nkwenti, I have a few digital clock circuits but I am not not sure whether translation may be possible or not? You can see them below
https://www.homemade-circuits.com/arduino-digital-clock-using-rtc-module/
https://www.homemade-circuits.com/7-segment-digital-clock-circuit-using/
https://www.homemade-circuits.com/digital-clock-circuit-using-arduino-and/
https://www.homemade-circuits.com/simple-digital-clock-circuit-explained/
Yes definitely, you can use the earlier referred link to detect CDI spark rate and accordingly set the corresponding output from IC LM3915 to trigger a transistor stage for controlling the CDI
Deogratia says
Dear sir.
Hope all is well with you, i must take my time to first of all appreciate all your good efforts and help you offer from your website,
i have enjoyed a lot from your website, but i came accross a project from your website and i wonder if you can help do some modifications so that i can use it as my test projects coming up, i am basic but to build any circuit i have no problems doing that.
i came accross a circuite under auto-mobile projects, the car speed indicator, dear sir, is there any way you can modify the circuit in such a way that, when the CDI gives signal about you over speeding, a circuit automatically stops your engine for at least 5minutes?
Then as for the other help i will ask you is that, i am in need of a digital clock schematic that has date/month and time, if the digital clock can indicate time in French and English it would be excelent.
thanks for your understandings and i will be looking forward to be reading from you.
Nkwenti.
Swagatam says
Thank you Nkwenti,
I am sorry I do not have the digital clock circuit with month date, but you can perhaps find through a Google search.
For the car speedometer cDI controller you could try the following concept:
https://www.homemade-circuits.com/10-led-tachometer-circuit/
From the 10th LED or 9th LED of LM3915, an IC 555 monostable could be added whose output could be integrated with the CDI for stopping it as soon as the sequence reached these LEDs.
You can first verify the above circuit then I will proceed and tell you how to configure the IC 555 monostable.
Andreaas says
Thank you very much. I’ll try it out a.s.a.p.
What is the difference in power consumption between the first and second iteration of this design?
I’m probably being a pain, but can you give a breadboard illustration of both circuits. Or maybe a link to a VBB design.
Swagatam says
You are welcome Andreas.
I won’t recommend a breadboard assembly. This must be firmly assembled and tested on a veroboard, by soldering.
Secondly the resistors involved with the LDR transistor will require some tweaked until the desired results are achieved.
This circuit will not consume anything while it is in the standby mode…
Andreaas says
Thank you, I have made the circuit with both designs….555 and bjt, had to play around a lot to get both working because of the difference in ldr’s. I added a cell phone to the setup with a relay connected to the dial button. Now I want to add a power failure backup utilising the cell phone’s own battery and over charge protection and also add a comparator circuit to both ldr’s, so a would be thief cannot just shine his own laser to disable the system.
I would very much appreciate if you could maybe start a new post incorporating all these ideas into one circuit. I see you have a few other circuits that use some of these individually, but not one “fully incorporated” system.
Again, thank you very much for you patience and all your help.
Swagatam says
I am glad you could make it successfully. In order to make the design foolproof you could probably try making the opamp based circuit explained in the following concept:
https://www.homemade-circuits.com/how-to-build-dual-solar-tracker-system/
the shown motor could be relaced with an alarm, now if the intruder tried to balance the LdRs artificially he would fail drastically causing the hooter blow of.
Andreaas says
Thank you, you have been soooooooo much help.
I looked at the circuit you suggested sorry….I struggle a bit still with learning electronics…..how do I tie this into the 555 circuit, does pin 1 and 7 of the op amps go to pin 2 of the 555 as trigger?
Swagatam says
You are welcome Andreas, sorry I did not get, which IC 555 stage are you referring to? the suggested LM324 will not require any other circuit, it has two LDRs which can be used with the laser for getting a foolproof implementation.
Andreaas says
Hi Swagatam,
I made your smart alarm system that a guy from South Africa proposed recently and I really love the idea. Btw, i’m also from South Africa slightsmile emoticon ( the laser alarm system with two ldr’s,
“Smart Laser Alarm Protection Circuit using IC 555”)
I was wondering if you would be able to expand on the idea as follows :
I would like for the system to have a back up battery, so that it is tamper proof and also wanted to know if the same result could somehow be achieved without using the 555 as it is very power hungry.
Also, if you could incorporate a potentiometer or something so that the light intensity can be adjusted on the ldr’s. I am planning on putting mirrors around an area of 4 meters by 2 meters square for the system and the laser light is quite diminished by the time it has gone around that whole area.
If possible, could you also let me know what a “kit” like this would cost.
(Sent you message on Facebook, not sure if you got it, so sorry if i’m repeating the same 😉 )
Swagatam says
Hi Andreas, I am glad you could make the project successfully.
I have noted the improvements suggested by you, and will try to update the article with the modified design soon.
Andreaas says
Thank you 🙂
Another question, if i may…..
Could one include various RC combinations and toggle them with a sweeper switch? I.e. 10 second RC combination, 30 second and 1 minute on a 3 pin sweeper switch so that you can choose the duration that the alarm will sound?
Also, which changes would one have to make to include a gsm combination as in one of your other posts or can one just tie the one you made in on the pin three of this circuit?
Again……Thank you very much for your help and dedication with this site. YOU ROCK!!!!!!
Swagatam says
yes that’s also possible, in fact you can use only the Capacitor for the selection and get different time periods.
sorry I am not too sure about the GSM integration, it will require some thinking…
Andreaas says
Thank you. 🙂
Swagatam says
Andreas, I have updated the design under the following article:
https://www.homemade-circuits.com/smart-laser-alarm-protection-circuit/
Andreaas says
Thank you for this site, it is a great help to a great many people.
Swagatam says
Thank you very much Andreas!!
Waseem says
Hello Sir,
Hope you will be good.
I am a big follower of you, will you guide me how i design 2.5kva gasoline generator AVR or please share if you have any circuit related portable generator AVR.
Waiting for your guidance.
Regards,
Waseem
Swagatam says
Thank you Waseem,
Although I am not sure how to control a generator output, it may be perhaps done by controlling the CDI ignition rate through a feedback from the generator output voltage…if possible I may present the concept as a new article.
teguh says
sir how to dim and use 6 or 12 volt batery to drive 50 watt led ( using TL494) thankyou for your attention sorry my bad english.
Swagatam says
You can try the following concept
https://www.homemade-circuits.com/5v-pwm-solar-battery-charger-circuit/
you can remove the coil and associated diode.
manash Athparia says
Hello swag. I am a regular visitor of you blog and it is awesome.
I am trying to make a modified sine wave inverter. I have one unused raspberry pi 3, so I though of using it for generating pwm signal and use it with a square wave inverter. Will it work?
Swagatam says
Thanks Manash, you can use any PWM source to create a modified sine wave, it doesn’t matter whether it is from an ordinary circuit or from a Rashberry pi or Arduino, all will produce similar results
manash Athparia says
But the pwm output voltage is 5v. Can I directly connect it?
Swagatam says
No that will not do, for that you may have to employ the second circuit configuration from the following article
https://www.homemade-circuits.com/arduino-pure-sine-wave-inverter-circuit/
Umar says
Hello!
First of all I’ll appericiate you for your work.you are doing very good job…keep i up!
Second I need a circuit which will need the following paramters.
1. Run the motor after specific interval e.g after each hour.
2. Motor should run off when there motor is not supplying water in upper tank (means dry run protection in upper tank.)
3. If upper tank is full,motor should not run.
4. If there is high or low voltages from a certain voltages than motor should not run.
5. If there is power failure during startup, than motor should start after delaying some certain time when power restores(delay startup).
I hope you can help me on this.
Thanks in advance.
Swagatam says
All these circuits are already published in my website in separate articles, you can search these articles and join them together for fulfilling the specified needs…
Umar says
Thanks for your reply!
I am very initial level hobbiest and could not enough knowledge to merge different circuits according to my requirement. Kindly guide me some so I can up track on my requirements. Or atleast give me list of you articles with guaidence to join these circuits which you think that can fulfills my requirement.
You are doing very good work, and your website lead me to stay on from yesterday and i have bookmarked your website.
Swagatam says
Thanks Umar, appreciate your interest.
I think you should proceed step by step.
for the timer circuit you can try the following design, if you succeed then we can move ahead with the next stages.
https://www.homemade-circuits.com/submersible-timer-circuit-with-pause/
Sandipani Sahoo says
Sir I need ur help
I want to make a 2.5 kW inverter
So sir give ur personal mob no
Madina Shanu says
to u and yr family.
Sr i want to glow up 7000 to 8000 leds with 220 v ac and want them just blinking.
Kindly guide and help me giving a appropriate ckt.
Thanks and best regards in advance
jamil ahmed says
Hello Sir,
My name is Jameel Ahmed
my english is not good.
I want a Electricity Power Saver circuit for Home Application for saving power consumption,
Shivam Chauhan says
hello sir
sir, In my flat there is a problem of light cutoff when alternating current gone. Our building's gate keeper start generator and we have to switch off all extra load (e.g fridge, a.c etc). There is nothing to notify when light comes again. Is their possible to detect generator current/voltage/freq. or alternating current/voltage/freq. . Please help me sir
my gmail id is shivamchauhan20sep@gmail.com
Chetan Vernekar says
Hello sir
I am chetan from karnataka
Sir is there any circutes regarding monkey repeller
kindly help me about this.
Amandeep Singh says
Hello sir,
I want to make 3RCA TO 6RCA Female cable and 3RCA TO 3RCA+RJ45 Female cable. Will you please provide me circuit for it. Pls do the needful
Thanks
Amandeep
Nishant Sheth says
Hello Swagatam,
I would like to meet you and discuss projects for welding machine. I am Mumbai based. My phone – 9820212263.
Any time will be convenient to me. Please reply.
Much awaiting,
Nishant
Ajitkumar vk says
hi sir
thanks for this valuable blog
please post a Brushed DC motor speed control circuit up to 10hp
Ajitkumar vk says
HI Sir
Thanks for this valuable blog.
can you post a brushed DC motor speed controller circuit up to 10 HP
J-max Videos says
Hi sir i need a ckt for a present. Would you plz make a ckt for me
saeed salimian says
Hello Sir
Do you have schematic of electric bike especially brushless motor and controller , how can i make a ebike for my self
thanks
Unknown says
I want to make a led lighting circuit which will show the blood flow of human heart including open close indication of valve. Can you help me to do this project providing circuit diagram and details . I want to use 230 v ac supply for input. Kindly reply me in my email id uniqash@gmail.com.
sakthi stabilizer says
HI SIR,
I NEED 3PHASE VFD CKT
bahari benoit says
i like to build led sign but i have small knowlege with the pic16F And attiny 2313 That i try to study them. I asked my friend to help me because he has many knowlege in electronique than me.
My dream is to drive many leds on one pin µcontroller. But i can't make it now.
Perhaps swagatam will help me to solve this problem,thanks a lot for your good site.
Ravindra Singh says
Hi Swagatam,
This is RSBirman.
Do you have any circuit which indicates open earth and has a NO/NC relay contacts which can trip the contactor if the earth is not connected and this will avoid the instrument from getting on.
The sensitivity should be adjustable.
Lahiru Jayawardane says
Hi,
I recently by mistake bought LED bulb(Great Value) from South America which is 110V. But I want 220V LED Bulb as I'm in Sri Lanka. Now I'm trying to do some modification on LED driver. Please help me to do this & Fix this bulb to use from 220V. Which parts need to change on the driver ?
Saeed Abu says
220v Ac COB 5w(5A) Led is getting excessive heat after connection. Also not lasting. How can I solve this problem???
Henrik Lauridsen says
Hi Swagatam,
I need a countdown timer with a relay which can be set to 1 to 5 minutes.
I would like the timer to show the preset time on 7 segments e.g. 3 min. = 180 or 3.00
When the time counts the 7 segments shall show the remaining time.
When the time is up the relay must switch off.
I don’t have Arduino and no skills in PIC programming yet.
Can you help me out with a circuit / schematic?
Thank you in advance,
Henrik
Sinivas Putta says
Dear Mr. Swagatam Majumdar,
My name is Srinivas Chakravarthi & I am working on Electro-Chemical project, for my lab work, I need an Universal Power Supply (AC/DC) with variable Voltage, variable Current & Time controlled Polarity Switching.
My requirements are:
Variable Voltage 0-100 (V),
Variable Current 0-100 (A),
AC or
DC with or without polarity Switching (1 to 10 minutes variable).
If you can make one such universal power supply unit, I shall be very much grateful to you.
Thanks & Regards,
P.Srinivas Chakravarthi.
09440840989.
Vijayawada,
Andhrapradesh.
kamal Colors says
Dear Mr.Majumdar, I am Kamal Kumar from Chennai.
I hope to find a good circuit for a battery eliminator with output dc power ranging from 1.5 to 12 or 15V and with its PCB design etc. can you kindly give me the same I will be very thankfull. I have searched every where on the internet but nothing seems good for what I am looking for. Thanks in anticipation.
Amit Kesharwani says
Hi Swagatam I am a fan of ur work..
I need a help.
My laptop and mobile over charges each night.
I want to creat a circuit that can start supply at desired time later i.e that 2 or 3 or 4 hrs later and supply should should be ON again for desired time .
I would have to enter how much time later Supply will be on and off..
Thnx man, Your work is really great.
Please inform me if you are working on this project.
Lissandro says
Hello Swagatam. I was thinking about put a sensor on the gasoline line from my motorcycle tank, near top, between the tank and the carburetor, that would consist of a pair of (innox?) leads like some mm separated from each other. This would detect the electrical conductivity inside the line, in direct contact with the fuel and while there is gasoline wetting it, it would output 0 volts, and when not (i.e. gasoline is ended and the line is becoming empty from the top), it would output positive (12v?) so I could light a warning light on the dashboard to avoid getting engine cut on a sudden. I can quickly turn the valve from to reserve position in this case. So when sensor wet, 0V(0); sensor "dry" 12V (1). What do you think? Thanks Sir.
Botwire says
Hello,
I love your website! I was looking at your circuit "twin or split battery charger" and I don’t see a value for the resistor between pins 1 &3, 7&5 for the LM358 is it 1k? I’m going to make a printed circuit board of this design using photo etching.
My goal is to build a circuit that will charge one battery while running off another battery and when the run battery falls to a certain voltage level, switch to a charged battery. I am not looking to make an over-unity device; I am interested in experimenting with energy recovery to create long pulse motor run times. I expect the system to eventually die out but I want to see how long that process will take using air coils and back emf harvesting.
Would this circuit work if I replace the batteries with two 100F 2.7v supercaps? Since the caps charge faster than lead acid batteries, this may help the efficiency of energy recovery during the run time windows.
I love building things and your awesome ability to design such cool circuits makes people like myself enjoy hours of building these cool circuits and watching them come to life.
Syed Ghouse says
Dear sir, i am very fond of u, by u i love electronics, u r really genius, u made electronics very simple.
Sir i would like to request clap switch and timer circuit for 8 volts led bulb which remain on for a long time
Please help me to solve the circuit.
Thanking u
Yours
Money makers online says
hello sir,
i really liked the way you reply to queries and your good heart of sharing. May God bless you.
please sir, am working on a project titled "remote controlled DUAL BAND MOBILE PHONE JAMMER"
i hae tried searching for a working circuit diagram but hae been able to find one. please i will appreciate it if you could be of help. thank
johnson
Aj says
Hey mate,
Would you be knowing the circuit for a zero cross detect for a transformer ?
Aj says
Hi Mate,
I am designing a Spot welder Controller with an Arduino and there is a need for a in rush current limiter. Would it possible for you to design the "In-rush-Current-limiter" i have read that it can be done in several ways. I will be using this to drive a Microwave oven transformer modified by rewiring the secondary to 3 turns of 3AWG wire for spot welding 18650 cells.
David Montenegro says
Hi Swatagam!
I would like to know if you could make a circuit that can activate a 12V 600ma stepper motor for 10 or 20 seconds every 3 hours or so. is that posible?
Kind Regards,
David Montenegro
Dr Ankit says
Sir, plz help me in making a circuit with following details. A 12 V relay is to be connected such that a momentary push switch turns it on BUT but after release of switch the the relay should not turn off immediately, rather it should turn off after some time say roughly 1minute. Thanks
Saeed Abu says
Hi I need a Nokia Mobile battery( 3.7v) driven simple Bluetooth stereo amplifier circuit diagram.Please develop it.
rakesh singh says
Hi,
I would like to convert ATX power supply to a variable power supply, can we do it ?
Anand Rampuria says
Sir your projects are really great but I am a student of class 10 sir can you help me with a idea of creating a project for science expo.
Swagatam says
Thanks Anand, provide complete details of your requirement, I'll try to help.
FARHAN NASEEM says
i need to assemble variable frequency(a pot can be use on output of 555 for variable amplitude) square wave funtion generator with frequenciies 1 Hz to 1MHz ,flexibility to vary amplitude of output ,555 should be used in astable mode and axact 50% duty cycle can be obtained on output plz help me sir in desining the above circiut i will be highly thankful to you
Dhairya Saluja says
please sir i want talk to you over phone is it possible? my mail address is
ravishimla1965@gmail.com
Thilina kumara says
Dear swagtom sir! I have heard that we can communicate by intercom using main ac power line home to home , i need communicate with my friend , there is about 3km-4km between our houses, but our ac power line is same, can you give me circuit communicate with him? please!
Swagatam says
Amit, I'll try to do it soon.
amit kumar das says
dear sir, i will enough grateful to if you can provide me the complete circuit for e rikshaw with solar system alongwith complete electronic component value, please send it to amit46vm@yahoo.com/gmail.com
regards
amit
Disha Karnataki says
This is just a simple question :
Can i use a lower Ah battery charger(say 20,30)to charge a higher Ah battery ie 110Ah?What are the consequences?
What is the difference in the charger circuit in both case?
Aravind B Kumar says
Hello Sir
This Is Aravind Sir
I Like To Know How To Make A Transformer And Its Calculation And I Google It But I Cant Find The Proper Calculation Method And I Find Around 7 Method Of Calculation But Its Not Proper With Manufactures Standard And Can You Please Help Me To Know It Sir
Thanks You
Dinesh Khandal says
Iwant to make my own polybag sealer can you give circut of this
swetha bindhu says
Hai Sir, this is Swetha…, Am persuing Btech final year. Want to do live project. I want Gravity Light project. Can you please send circuit diagram and report please. swetha.bindhu403@gmail.com
yus kad says
hi sir i can you please design a circuit which will output 9v dc from a 12v battery efficiently . it can be by using ic 555. this will be use to run a rc toy car using 0.8A max. if possible can it be a variable output voltage dc. i have a 2n3055 transitor ,MJ11015 TRANSISTOR.
Vinod Sharma says
hello sir ,this is vinod from mussoorie near dehradun.i am not an engineering student,but i have lot of interest to make different electronic items . sir i would like to know that is it possible to use usb drive in normal tv without hdmi and usb port, by putting some type of converter in between them.if yes please tell me the circuit diagram .
Dr Ankit says
Dear Sir, can talking circuit be made eg it speaks "Welcome" running on 12 volts.
Thanks
Kevin Dearing says
I'm trying to make a circuit that will turn on them off a pair of 12v pumps in sort of a heart beat pattern, repeatedly. U haven't come closer. Any way you could help me with this?
Unknown says
I'm trying to make a circuit that will turn on them off a pair of 12v pumps in sort of a heart beat pattern, repeatedly. U haven't come closer. Any way you could help me with this?
Shayan Firoozi says
Hi again ,
thank you for all help you providing 🙂
i think this circuit could be useful and after searching many sites i could not found a good circuit !!!
i need a circuit which get 2 input for 12 volt DC 5 AMP power supply , and give one them in output ,
if primary power supply fails , secondary power supply take the action , something like Redundant Power Supply,
to my knowledge we could do it in 2 way
1- ORing Diodes
2-Fets
would you please design a circuit like that ?
Unknown says
hello sir
I am zulfiqar
I want to make a project which control the the lights, fans (and other appliances that are used in one room)
from the another room .
I have to use two controlller and a single wire communication between them
If i press light button light should be on of other room and i press fan button fan sholud be on
I have to controll the 8 things using two controllers
Kindly help me in makin my project I will be greatfull to you
Rajan Lopez says
how to connect LEDs such that it works like a series?
Chandan Parashar says
Dear Swagatam,
Greetings of the day.
Can you send me the link of circuits which uses remote bell to energise a relay, making it wireless relay activator.
Shubham Trivedi says
hello sir this is shubham from maharashtra india,
Sir my question is how general sine wave of a oscillator (consider colpits or hartly oscillator is differ from the sine wave which we use to power all AC powered equipment's. Is this possible that we can make a inverter circuit by using hartly or colpits oscillator, if yes then how? Please give me reply sir. Thanking you
amar yadav says
It looks good that you are doing lots of hard work for all your projects
But i here wanted to you to suggest you to make your website more ineteractive &attractive for the user
becoz if your site will be interactive then people will often like to keep on visiting it's an important aspect with your
toil hard work . Thank U
Walter Marafioti says
hello Swagatam can you help me with a power supply drawing for a grow led light?
direct 220 to a chain of 3 watt led ratio 4 red 1 blue
best regards walter
shefali parmar says
Hello Sir
I am working on a project of designing 40W/15V SMPS. I have all schematics of 65W and triple output of 5V, 15V,-15V SMPS. for this SMPS feedback circuit is designed for 5V output. I want design Feedback circuit for 15V output. can you explain what changes i have to make for this and how would i chose parameters for feedback circuit. I am using NCP1203 for switching. My emailid is shefalip.06@gmail.com. Please sir send me your email id so that i could send you all schematics.
geraldo eustaqyuo says
hello friend, I am passionate about electronics and also am one of your admirers around the world. I wonder if you have some scheme of some electronic circuit able to control equipment from a distance, via mobile phone, gps, etc, because we need a device on and off the distance that can be locked. If you already have some mounted, I am interested in buying from you if it is not too high. I appreciate the attention, any questions can explain more detailed via Skype If you possess. thank you
Unknown says
hello friend, I am passionate about electronics and also am one of your admirers around the world. I wonder if you have some scheme of some electronic circuit able to control equipment from a distance, via mobile phone, gps, etc, because we need a device on and off the distance that can be locked. If you already have some mounted, I am interested in buying from you if it is not too high. I appreciate the attention, any questions can explain more detailed via Skype If you possess. thank you
Rahib says
Hi Swagatam,
Nice blog you have, I am actually looking for a transformer less power supply something like mobile chargers but i want to operate relay using it, could you please help me with this. Do you know any place from where i can order these circuits or if i can myself make it at home.
Any help will be appreciated.
Thanks & Regards,
Saiyad Rasikh
Anand vernekar says
Dear Swagatam,
Searching for small invertor circuits i reached this website , i got a 100 watt invertor circuit diagram on this website which uses
4047ic and irfz44n mosfet and successfully got running invertor thank you very much for this.
now on the same lines using this same 4047ic circuit i was trying to develop a smps with higher frequency unlike 50hz above
this time using irf840 mosfet and ferrite core of size 35mmX28mmX12mm primary winding of 300turns and seconday 18turns
i am facing the problem of irf840 getting hot quickly and also this ferrite core transformer making vibrating sound squeaking sound of
the high frequency of about 12khz to 18khz , actually i am not electronic educated but mechanical engg but having very much interest in developing and trying self useful electronic circuits
kindly help me understand what makes mosfet to go hot quickly and transformer making vibrating squeaking sound
thanks
anand
Omkar U. Pawaskar says
Sir i am omkar pawaskar
i want to make a wind based mobile charger which can charge my mobile when i ride my bike
m trying this from long but have failed pls guide
omkar pawaskar
Astral Concepts says
hello sir,
i want to make IR based fan regulator with 5 speed fan control it should not work like dimmer as dimmer based regulator make fans to create noise on slow speed. can u plz help me
vinayak says
Hi Swagatam,
I want to design DC-DC converter using OP-AMP. Specification is 12 VDC input and 48 V DC output. Can you please give some related circuits
Yalishanda Crs says
Hi swag, do you know Grid Tie Inverter with Limiter? Can you please design me a limiter that I can connect to any ordinary Grid Tie Inverter? Thanks
Swagatam says
Hello Andre,
I'll try to design the circuit for you soon and let you know, by the way please do not post on this page as it has stopped responding to comment postings
Andre vdv1 says
Hello Swagatam,
I was wondering if you could possibly assist me. on the blogs I have seen some diagrams for simple variable power supplies. Firstly I know very little about electronics, but with a shopping list and a diagram I am sure I would be okay. I would like to build a simple variable power supply with an input of 220/240 volt ac and an output variable voltage of approx. 1.5V to approx. 15V and a variable output current of up to approx. 100A. I have started zinc electroplating as a hobby (have sweaty hands and want to protect all my tools) the chemical company gave me these as a more or less dependant on my zinc plating bath size. At the moment the little 6V 8A Ryobi battery charger works for a few minutes, overheats and cuts out till it cools down again. I would really appreciate any assistance you could give me on this.
Many thanks
Andre
Anwar Peternak says
Dear Mr. Swagatam,
Happy New Year 2015……
GOD Bless You…….
I come from Indonesia…
I am Great fan of you, I like to go through your blogs and also the comments.
So finally I got inspired and start to work on very simple requirement of mine.
Please Help me Sir,
so I Need Timer 3 Hour intervals and now I Have Schematics Two Hours….Can you help us to change its?
Uploading the circuit diagram is not possible here so I have sent it via your email address hitman2008@live.in and homemadecircuits@gmail.com
Best Regards,
Anwar
Ebrahim Al-sakkaf says
Dear Swagatam,
I want to design DC to DC converter, Like 18 V from two battery 9V in series, by using I 200 or LM7809 to get 9 Volt with 600 mA, I can get the 9V from regulator, but I can not get 600 mA, How can I get the 600 mA.
Thank you
Sanjeev Aveva says
Hello everyone.
I'm a electronic novice, and would like to purchase a simple timer circuit.
I'm located in Hyderabad.
Thanks..
Sanjeev
email: asanjeevomatic@gmail.com
Raj Mukherji says
Hi,
Hope you are fine. 🙂
The purpose of writing here is to share with you an idea of a project – to design a "heart rate monitor alarm" which can be made by using commonly available low cost components and which will produce an audible alarm whenever the pulse rate of anyone is found to be abnormal. It should meet the following conditions as well:
a. Compact and light weight, therefore portable
b. Consume minimum power, therefore should run 24×7 for a month or two from a couple of AA batteries or a 9 volt pack
c. Should be fairly accurate in it's performance
I know there are many such circuits available on the net but their performance and reliability are questionable. The unit can be very useful especially for elderly people (with / without a heart disease), for patients who are bed ridden and so on. When the heart either beats at a rate higher/lower than a set average threshold value, the alarm will sound loudly enough to alert people around the patient.
I hope that my proposal is clear to you. However, if you have any doubt, please drop me an e-mail.
Thank you,
Kind regards,
Raj Kumar Mukherji
Swagatam says
….
Unknown says
Sir, Can you provide me with a circuit to scare birds circling around our gatherings in park.
Thanks in advance.
E.R.Murthy.
I Capatosta says
In the https://www.homemade-circuits.com/2012/05/make-this-emf-pump-circuit-and-go-ghost.html how do you wire the cols
Is it a single wire or multiple wires – the coild picture seems to show 3 wired on the lower right coil and only two wire for the other 3 – Where did the third wire come from ?
Sorry for the stupid question I'm a noob
Swagatam says
This page is not responding to comments, however I have read your comment which you have posted, I'll do the required corrections in the DRL circuit.
siddu says
Hi Sir,
I have TVS heavy duty bike and I want to it convers battery I mean how to fix the battery along with please send me the circuit diagram to my mail id ssinnurs@gmail.com
siddu says
Hi Sir,
I have gone through your technical review very helpful.
Hunain khan says
Hi,
I need a circuit to start an Electric Generator automatically when power is failure, and then stop it when main power is ON. can you help me? is there any idea based on 555 timer sircuit using SPDT relay.I have a 3KV electric generator with selfstart option.
Thanks.
Prabuddha Koralagama says
Hi,
could you please publish 3 phase regulator rectifier circuit for motorcycle . thank you
SarAnG shAstRaKaR says
Hello sir,
I need a circuit which will make 12 volt relay initially On, as soon as I trigger, relay should get OFF until I restart the hole circuit. Relay should stay OFF irrespective of thereafter triggering.
Ahmed Sabra says
hi Swagatam
i have an ic voice recorder model vr330
at first it was working well
recently it always shut off "battery low" i replaced the battery but no success.. i used lm1117 3.3v but also the same result.. it always tell low battery and shut down..
i checked every single item on the board but didnt find any item harmed
is there any chance that i could fix it ?
thank you
Swagatam says
3 in series with a 6 ohm resistor
Ullah Nadeem says
Hello Sir Can you tell me how many 1 watt LED I can use in series on 12v 500mAh charger usually use for modems etc. Do I need any resistor to do such. Regards
Dan Andrei Andor says
Hi i have a request :D, if it's possible. a circuit for a DRL (day running light.) made with 10 LED white, the circuit for led must be with impulse (impulse control) a potentiometer for frequence control , frequence between (i can see the led blink -and- over eyes can percept). if you have a idee. V=12 V
Swagatam says
Bhanu, email addresses are given in the above page
bhanu prasad Mishra says
Sir how can i send you a circuit in your email id or what…. I want to send a circuit …..me bhanu
leen agustin says
Hello sir, I really need your help. Any suggestion of a circuit or electronics components I’ll be needed to build a circuit for an automated conveyor that could detect if the boxes are large, medium or small and sorted them to 3 different directions. The size of the conveyor is 10 inch by 18 inch. By the way sir I’m from Philippines and I’ am a currently second year college student taking up Electronics and communication engineering, and that project was my final requirements for industrial electronics sir. I really hope you’ll respond as soon as you saw this. Big thanks to you sir. Have a good day
jnroad says
Hello sir.
I want to make simple SMPS welding machine for my personnel use .if u have any complete circuit and design please help me.
thanks
Swagatam says
The circuit presented in the following link is correct and will surely work, although it's not yet tested by me, but I am sure about it.
2.bp.blogspot.com/-Kn2Xo60G6wc/Txl5qizRSFI/AAAAAAAAAvM/Qbv2xxlIX6c/s1600/Musical+Door+Bell+with+Timer%252C+Circuit+Diagram%252C+Image.pn
Kaushik Mondal says
I made the circuit "Simple Door Bell Timer, with Adjustable Timing Facility" but it is not working. A few days ago I saw the same circuit in your site with some modification using bel8550 and 8050 transistors with some change. I am confuse that which one is correct and tested o.k. Please clarrify.
Ajay Dusa says
Could you post a circuit on Automatic water plant system…using some relay and transistor…..
Swagatam says
This page has stopped responding to comments, please don't post your comments on this page.
A.W.FRANCIS says
Hello Swagatam –
Your site is very good. Specially for those interested in Electronics & in Building. I have a Little Problem as I am just an electronic hobbyist. I am not aware much about the Components. Can make a Article page on this site explaining in details how to use PCB's, Correct way of connecting LED, Resisters, Diode's, Color Coding of Diodes, etc.
This will help a New Hobbyist to learn a few circuits building. There are many Ready to build kits in the market and we get all the parts mentioned in your blog easily but are struck when we have to make the connections as we get confused as to which wire has to be connected to Positive point or Negative Point. If we connect it wrongly the project may fail and if the project involves main current then the damage may be Great.
Hope you get my point.
Thanks & Regards
Francis
Swagatam says
it'll require microcontrollers
Ajay Dusa says
Can you post new like Led Propeller Clock or Rotating Led Globe it is difficult but very interesting…….
Syed Arham says
i want circuit to get DC 100v 350mA from 220vac..sir plz help me… 🙁 …
Osama Butt says
Hello Sir
I want to built static voltage stablizer using IGBT, can you help me with some proteus simulation circuits and codes
Swagatam says
Dear Gill,
the last circuit shown in the following article shows an inverter with auto-load control feature, however it will work only if the entire design is built as per the diagram:
https://www.homemade-circuits.com/2013/01/300-watts-pwm-controlled-pure-sine-wave.html
Gill says
Dear Mr Swagatam, i am an electronics hobbyist and followed your work on this site for some time now. I have learned many things from it and i like to thank you for that. For my next project i like to make an inverter with parts salvaged from obsolete ups's. I have a 2kva transformer, a print board with 16 mosfets PN80NE0 full bridge driven by 2 ic's IR2110. Do you have a circuit with load dependent correction for me that i can use?
Thanks in advance
Best regards,
Gill
Swagatam says
thanks filipe
Swagatam says
Raigon, please see the circuit shown in the following link, use only the IC2 section which is an IC555 circuit, it will respond accurately as per your desired settings, you can connect a relay directly across pin3 and ground for toggling the load
https://www.homemade-circuits.com/2012/10/automatic-40-watt-led-solar-street.html
pawan singh says
helow sirr ……I hav got a project on single phase transformer……if u don't mind den can u plz say me abt its construction n components to required to build a one phase transformer……my gmail is pawan.singh2069@ gmail.com
Ashish says
dear sir
how to make dipawli decoration light cuircut
1. runing light
2. on off light
BASHA says
hello sir iam basha your projects most sinceyarli warking
your 2 to 5 kms fm transmitar project i like it sir so you made this project my adress send me sir this project money i paying sir
please made and send me sir thanq
BASHA says
HAI IAM BASHA YOUR MADE LONG RANGE FM TRANSMITAR I LIKE IT SO IWANT IT HOW THE PRICE OF THIS CIRCUIT MADE PLEES TELL ME SIR IAM ORDER THIS PROJECT MY NATIVE PLACE IN ANDRAPRADESH GUNTUR JILLA
Swagatam says
Hi Tapas,
Thanks very much!
I am afraid you will have to buy a readymade SMPS for driving them because making one at home could be extremely complex.
With a 12V/3amp smps you can use the last configuration as shown in this post:
https://www.homemade-circuits.com/2013/06/universal-high-watt-led-current-limiter.html
patel krunal says
hello sir,
i want to make one miniature electic stove so please give me some tips to make it….
waiting for your reply….