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Questions & Answers
Hi. I am a Senior High School student . Our research is the same as you, but we are using photoresistor and LED bulbs. our goal is to decrease or increase the light in LED Bulbs depending on what the sensor(photoresistor) can detect in an environment(Ex. If your LED bulbs is bright and the environment is slightly dark ,the Led bulbs will decrease its light because of the photoresistor and it will balance into the environment) and it can also save more energy because we are using LED Bulbs. Our problem is that we do not know how to write a procedure in making our research and we do not know how to program a code in our research. If you have time will you please help us in making a procedure and a program code of our research.Please reply soon. Thank You
..
Hi, sorry my coding skill is not good, so can’t help you with this project. I wish I could do it!!
Hi sir thanks for fast reply. How about the procedure of making our research? If you have time please help us. We really need your help. Thank You..
Hi Tristan, if it’s without Arduino then I can help. For further discussion please post your comment in some other related post.
hi sir.
as you know pir sensor are expensive even the pet frendly tipe. i bought by an electronic shop the one’s without casing HC-SR501 i think but looks exatly like the ones that are on your explaining of pir how it works
im new to to electronics but know an very little bit. i saw your explaining on how an pir sensor work. but im trying to make it pet frendly. the sensitivity adjustmen is not low enough and even pic up an small leaf, bird at day and bat at knight. can u help me what to do or must i change the pir sensor thats in the middle of the module and if that’s the case. i cant find an part no so i can order it. i think its the HC-SR501
thanks alot and I’ll appreciate you help.
Hi johan,
you will need a filter attached to the PIR otherwise it will be extremely sensitive to all IR sources. The HC-SR501 is the recommended one which you will actually need to purchase. You may find other alternatives too, but the front lens is crucial for stability and a controlled sensitivity.
hi sir. thanx for the fast reply.
i am not sure what tipe of filter if its electrically and what or where and how to connect it or shielding in front of the ir or infront of the small white lens and what tipe of meterial to use.
sorry for asking details but dont know much ????
Hi Johan, the filter is in the form white dome shaped plastic, it can be fitted in front of the lens.
Hello Mr. Swagatam, thank you for the quick response. I have some ferrite transformers from PC sources .. My question is …. How can I use them for investors? From already thank you very much.
ATTE: Carlos from Argentina.
Hello Carlos, ferrite transformers require strict calculations, so I don’t think they can be used randomly without knowing the winding details accurately.
Hello, good afternoon, I am a faithful follower of the website. I have a question, I have an inverter with lm555 and modified wave cd4017 .. the problem with the transformer inverters is that iron without load also consume .. How can you make it more efficient? From already thank you very much.
Atte: Carlos from Argentina.
Thank you Carlos, Iron core transformer will consume some power, that’s the reason these type of inverters are less efficient. There’s no way to improve this except using a ferrite transformer…or may be you can try using a torroidal iron core transformer which will help to improve the efficiency quite drastically compared to normal E/I core iron transformers.
Thank you Mr Swagat for you time and energy helping people who want to know about electronics. I’m new here but I know you be of good help thank you sir
Sure! You are most welcome Osei!
Dear Sir
I have a small meat grinder that stopped working, I took it apart and checked the motor, it’s a 220-volt dc motor, I found an old rectifier and connected to the mains and the motor works but the motor has a lot of starting torque and I’m afraid it might strip the plastic gears, I was thinking about a soft starting circuit but I have no idea how to do it, also I live in the Philippines so electronic components are hard to come by, we only have Lazarda and a few other online stores but I haven’t found anything that would solve my problem, also I’m quite poor so it would have to be something at a reasonable price, please help
Dear Alan,
You can do one thing. Buy a light dimmer circuit, and connect your motor in series with it. You can manually keep the dimmer a lower control when you want to switch ON power. Then once the motor is ON with a slower speed, you can increase it to full speed manually. make sure to attach a large heatsink with the triac of the dimmer circuit
Sir;
We are currently final year B.Tech students at Govt, Model Engineering College and doing the final year project on this topic.
We had first modulated 1 kHz sine wave using a PWM modulation at 40kHz by SG3524 IC.
Then we used an L293D IC to drive an parametric array of ultrasonic speakers.
Our parametric array includes of 14 ultrasonic speakers arranged in 7 rows.
A modulated signal and an unmodulated carrier of 40 kHz is fed to each alternate rows.
Then we had successfully heard the tone of 1 kHz.
After that we introduced an music signal from mobile phone via audio jack and we were only able to heard a feeble sound at the output and which is also above a particular frequency.
If we input an audio signal of a speech, its absolutely nothing we heard.
Can you suggest a solution to this situation..
Hi Athul,
Your approach is perfectly correct, however the input has to be from an amplifier with a relatively high amplitude. Because we are using digital ICs here, which will be able to detect the input signals only if its around 5V minimum. A signal from a phone or any headphone jack will be in millivolts which the digital ICs cannot detect.
So make sure the input music amplitude is at least over 3V for effective detection.
Thanks sir..
One more thing, is a pre amplifier using LM386 enough or do we need any other audio power amplifier to serve our purpose.
Hi Athul,
Yes LM386 amplifier should work since its peak output will be equal to its supply voltage.
Thank you, Sir.
Let me check it and inform you later.
Dear Sir,
Very nice work by you.
Pls. advice me how to generate 1000VDC ( Max 1 A)from mains 230Vac, need simple Circuit. I tried with Voltage multiplier. I got >1000VDC with ‘C’ and Diode.
But it is not capable of handeling load even 10mA. Pls. suggest.
Thank you Uday,
for getting 1A you will require a transformer, because capacitors won’t give you 1A unless they are substantially big.
You can try the second design from this article, this s two stage multiplier and will give you only 500V RMS, you can add another series stage to get 1000V
https://www.homemade-circuits.com/generatoralternator-ac-voltage-booster/
use 5uF/400V PPV by adding 5nos 105/400V caps in parallel on each. This should be able to give you around 100mA. Increasing the cap value will proportionately produce more current
For 1000V, should i have to increase Voltage ratting of capacitor also.
It is not required, 400V is enough. These will come in series therefore will be ultimately higher than 1000V
Thank a lot.
Dear Sir,
One more suggestion required.
I have Diode bank of 100no, connected in series.(SF4007, Max Rev=1000V, iF=1A). I wnt to test this bank on full load.
Considering 0.7 drop of each diode x 100 nos=70 Volt. How much Max DC Voltage and current i can give to test this bank.
Hi Uday,
If the input is 220V AC, then the average output will be 110V – 70 = 40V DC but the peak will be 220V – 70 = 150V DC.
Current will be 1 amp if the diodes are mounted on heatsink, otherwise only 100mA to 300mA can be extracted without flaws.
you are welcome!
Thank you very much Sir.
please in need automatic phase selector from any available phases with circuit diagram.. 3phase circuit is no longer in your box again please add it for us sir. thanks in advance
Hi Tobi, you can take the help of the following circuit:
https://www.homemade-circuits.com/extracting-single-phase-voltage-from/
But am making a transistor amplifier, can it be replaced with transistos instead of MOSFETS & give good results?
I think BJTs will also work in the referred diagram, you can try it out. But a PCB is a must in any case to avoid connection faults
Hello Sir, well done in all?
Am so great full for the above formula U gave me but I have two challenges in the above circuit I gave U where transistor TR3 heats up but its temperature starts slowly and increases with time and also resistor R4 heats up but its temperature tends to be constant.
But when I disconnect off the BASE of transistor TR3 from the COLLECTOR of transistor TR1, TR4 does not heat up any more, so what could be th problem sir, thanks.
Hello Kakooza, if you disconnect the base of any transistor then it will simply stop conducting which will mean the amplifier shutting down or start malfunctioning….so that's not the correct method of troubleshooting.
If you are not sure of this schematic then perhaps you can think of changing it with another more reliable one.
here's one design that was been tested by me, and I found it extremely good because it stated working instantly without any adjustments
https://www.eeweb.com/project/circuit_projects/300-watt-mosfet-real-hi-fi-power-amplifier
Hello sir well-done, since I began working with electronics, I only have one transistor amplifier I have ever constructed and worked out for me very well but it's a low voltage amplifier(35-0-35 VAC) that's why I never used it to design the other amplifier which has a supply of 85-0-85 VAC.
Therefore sir I just need your help on how to modify this circuit so that it can work on a high voltage supply and below is it's download link;
3.bp.blogspot.com/_B8Dh2WXNvg0/S7jlUBgY9yI/AAAAAAAAEPg/BekCF03Vwk8/s1600/Amplifier OCL 150 Watt.png
Hello Kakooza, you will have replace all the transistors with substitutes having voltage spec higher than 100V….also change the resistor values proportionately using the following relationship
35/85 = existing value/X
X = existing value x 85 divided by 35
X will be the new value which can be replaced for the existing value
Thanks sir, previously I didn't mention for you the transistor which is heating up but it's TR4 MJE340 but am using C4793 in place of it and Capacitors C4 & C7, am using 22uF/400V so I really don't know cause am stuck but still for transistor s TR1,TR2 & TR3 am using MJE350 respectively so which of those could be the route cause of transistor TR4 to be heating up, thanks.
Kakooza, C4793 is fine with its specifications and matches with MJE340, but it could be a duplicate one, so it's better you replace it with another one or even better if you could procure an MJE340….I am sure the problem is within this transistor or with the parts associated with its leads.
Hi Mr Swagatam, am constructing a power amplifier with a transformer of supply 85-0-85 VAC but I got certain circuits from Google where by when I constructed one of it, it failed to generate the signal to the power stage and the second one worked properly but there is one transistor which heats up whenever I give it the above supply after it's rectified& filtered & eventually the audio sound starts to change to abnormal, so really need your help because I've tried everything but I failed to notice the real cause of that problem.
"But this circuit which worked out was designed for 65-0-65 VDC but my transformer is of 85-0-85 VAC!"
THIS IS THE CIRCUIT WHICH WORKED OUT FOR ME BUT DISTURBING ME SOMEWHERE
1.bp.blogspot.com/-TpWLQNNOl8I/Vbhhmqo_RGI/AAAAAAAAV6o/CmPvlGuLKhU/s1600/socl%2Bv-5021.jpg
Hi Kakooza, sorry I cannot find anything wrong in the circuit, not sure what may be causing the issue…may be the transistor is faulty or connected properly, or its base resistor is not OK.
Hi mr swagatam thanks for reply me, dear i have required a circuit of smps 500vAc to 12vdc 2A please help me
Hi swagatam
Actually I,m interested in Mr Singonet circuits for my Dc ups,how to use this circuit to sense 220VAC and flow the current of a 12 volts battery to the load,I have to do it with mosfes,but my load is 12volt and I need to supply it whenever mains fails
My load is rated 8 amp.max,pleasr suggest me a mosfet model
Thank you again
Mr Swagatam,
thank you very much
but i need something like this :
https://drive.google.com/open?id=0B2VgP4YQwP4EaGxZak9qRXc2N00
actually i need a very simple 220 volts indicator with LED , then i wanna replace LED with a mosfet to make a electronic switch
thank you again
Mr Singonet, you can do it in the following manner:
replace the LED points with the transistor gate(base) and source(emitter)….
gate(base) will connect with the C1/D1 junction.
Replace D1 with a 12V 1 watt zener diode, connect the anode on the neutral side of the indicated mains input….remove R1 it is not required.
now connect the LED between the drain(collector) and the C1/D1 junction with a 1K resistor in series with the LED
Hi Swagatam
I'm designing a mini DC UPS , so i need to detect main failure
i need an simple circuit which switch a MOSFET ON/OFF whenever main Fails or when get back !
it should be fast enough to protect my Loads from interruption
Hi Singonet,
you can try the following concept:
https://www.homemade-circuits.com/2013/03/simple-dc-ups-circuit-for-modemrouter.html
But in my battery datasheet said :
Standby use : 13.5-13.8 volts
Cycle use : 14.4-15.0 volts
is 14v safe for standby use ??
If you are not using the battery frequently then 13.8V will be better