A few of the interesting and useful hobby electronic circuit diagrams already published in this blog have been selected and compiled here for quick reference and understanding.
Making a Photo Cell using a Power transistor
This is an old trick I learned many years ago. Removing the round metal cap from a power transistor, in many cases, will reveal a photocell. Even those that don't reveal a photocell have a base-emitter region that is sensitive to light when the cover is removed.
As shown in the photo, the metal cap has been removed and the photocell is located acroos the base-emitter pins. This particular power transistor read 1250 ohms in darkness and 600 ohms under a light bulb. I removed the cap on a 2N456A and it does not show a photocell inside.
In darknesss, it reads 300 ohms. Under a light bulb, it reads 25 ohms. Removing the cover can be difficult. The best way is to use a dremel tool with a metal cutting disc. A small hack saw could also be used. A last resort would be to take a small pair of sharp edge diagonal cutting pliers and pinch the metal at the round edges until the metal is penetrated.
Grab as much metal as possible and twist the pliers and metal upwards to expose the inside. Be careful not to damage the base-emmitter region. The amount of resistance change,is going to vary with different types of power transistors.
Making small emergency capacitors
When you need a small size capacitor in an emergency, this is one method of making one. I made a 22 pf (.022nf) capacitor with pencil and paper as shown in the photo below.
You need a clean sheet of white paper, such as a typing sheet. You will also need a graphite pencil with a dull end and some scissors. As the size shown resulted in 22pf of capacitance, you will need a smaller size for smaller pf's and larger for larger pf's.
Your actual capacitance values will depend upon the type of lead pencil you used and the pressure you applied to the paper sheet. Start on one side and take the side of the pencil lead, making strokes to spread the graphite across the plate area and connection tab on one side.
Take care not to puncture the thin paper. Also leave a little room at the edges, so the opposite side plate will not short
The connector tabs should only have graphite applied on it's plate side. Turn the paper over and do the same thing on the opposite side.
The connector tab on the opposite side will be on the opposite end as compared with the front plate. Use a capacitance meter to test the capicatance.
If it is a smaller value than what you needed, just add more graphite to enlarge the plate area on both sides. If your tester doesn't identify any capacitance, check with an ohmmeter for a high resistance short.
You may have penetrated the paper and shorted the plates. Once you have the value required, take the scissors and allow some space from the graphite plates so you want be cutting into the graphite. Connect pg (gator) type clips to the connector tabs and install it in your circuit. This is only a temporary fix as the environment, moisture, etc., could gradually change the value.
Simple Touch Sensitive Switch Circuit
We all know about this little versatile chip which finds its way in almost all useful electronic circuits, yes our very own IC 555. The following circuit is no exception, it's a sensitive touch switch circuit using the IC 555.
Here the IC is configured as an monostable multivibrator, in this mode the IC activates its output momentarily by producing a logic high in response to a trigger at its input pin#2.
The momentary activation time period of the output depends on the value of C1 and the setting of VR1.
When the touch switch is touched pin#2 is pulled to a lower logic potential which may be less than 1/3 of Vcc. This instantly reverts the output situation from low to high activating the connected relay driver stage.
This in turn switches ON the load attached with the relay contacts but only for the time until C1 gets fully discharged.
Simple Triac Dimmer Circuit
The circuit of a simple triac light dimmer shown below can be used for dimming incandescent lamps directly from AC mains.
The circuit is very easy to construct and uses very few components. The pot is used for controlling the load power or the intensity of the light. The dimmer circuit can be also used for controlling ceiling fan speeds.
Simple Audio Power Amplifier Circuit
The circuit illustrated here is probably the simplest form of an audio power amplifier.
Though the circuit is very crude by its specs yetis able to amplify an audio input up to a powerful 4 watts in a 8 Ohm speaker.
The transistor used in this amplifier is a 2N3055 is used as a switch for inducing voltages in response to the input signals into one half winding of the transformer.
The back emf generated across the winding of the transformer is effectively dumped over the speaker generating the required amplifications. The transistor needs to be mounted on a suitable heatsink.
Simple Water Level Alarm Circuit
Just a couple of transistors are enough for implementing a simple water level alarm circuit and used for getting a warning signal when the water level inside a tank nears the overflowing level.
The two transistors are configured as a high gain, high sensitive switch, which also is capable of generating a tone when the shown terminals get bridged through the terminals coming in contact with the water inside the tank.
The water offers just about the right resistance value across the specified points of the circuit for initiating high pitched tone or the desired warning alarm.
Simple Temperature Detector Circuit
A very simple temperature indicator circuit can be built using the circuit shown in the diagram. A generally purpose small signal transistor is used here as the sensor and another active device in the form of a1N4148 diode is used for providing a reference level to the sensing operation.
The heat source which is to be measured is place in contact with the transistor while the diode is held at a relatively constant ambient temperature level.
As per the setting of the preset P1, if the threshold is crossed by the introduced heat source, the transistor begins to conduct substantially, illuminating the LED and indicating the generation the heat beyond a particular set limit.
Parts List for the above simple transistor hobby circuit
R1 = 1K,
R2 = 2K2,
D1 = 1N4148,
P1 = 300 Ohms,
T1 = BC547
LED = RED 5mm
100 Watt Transistor Based Inverter Circuit
Inverters are devices which have important applications where normal electric supply is not available or difficult to obtain through conventional routes.
The simple 100 watt inverter circuit shown here can be built and used for powering many electrical appliances like, lights, soldering iron, heater, fan etc. The whole 100 watt inverter circuit mainly involves transistors and therefore becomes easier to construct and implement.
Parts List
R1, R4 = 330 Ohms,
R2, R3 = 39K,
R5, R6 = 100 Ohms, 1watt,
C1, C2 = 0.47uF,
D1, D2 = 1N5402
T1, T2 = BC547,
T3, T4 = TIP127,
T5, T6 = 2N3055,
Transformer = 9-0-9V, 10Amp, 220V or 120V
100 Watt Transistor Power Amplifier Circuit
This circuit of a transistor power amplifier is outstanding with its performance and is able to provide a thumping 100 watts of pure music output.
As can be seen in the diagram it utilizes mainly transistors for making the amplifier and its implementations and a handful of other inexpensive passive components like resistors and capacitors. The required input is not more than 1 V, which gets amplified 200,000 times at the output.
Please refer the article below for the parts list:
https://homemade-circuits.com/2012/01/how-to-make-hi-fi-100-watt-amplifier.html
Simple Automatic Emergency Lamp Circuit
This simple emergency lamp circuit uses very components and yet is able to provide some useful service.
The shown device is able to switch ON automatically when mains power fails, illuminating all the connected LEDs.As soon as power is restored, the LEDs shut off automatically and the connected starts charging through the built in power supply.
The emergency light circuit employs a transformerless power supply for initiating the explained automatic actions and also for trickle charging the connected battery.
Parts List for the above CIRCUIT DIAGRAM
R1 = 220K,
R2 = 10K,
D1, D2, D3 = 1N4007,
Z1 = 15V 1watt, zener diode,
C2 = 100uF/25V
LEDs = white, high bright type.
Automatic Day Night Light Switch Circuit
This simple transistor circuit can be used for monitoring the dawn and dusk conditions and for switching lights in response to the varying conditions.
Thus the day night light switch circuit can be used for switching ON the connected lights when night sets in and switch it OFF during day break. The threshold tripping point may be set by adjusting the 10K preset.
The capacitors are 100uF/25V, the transistors are ordinaryBC547, and the diodes are 1N4007.
Electronic Candle Circuit
This is a simple hobby project and exhibits all the properties of a conventional wax type candle. Here the LED is used in place of the candle flame, which illuminates as soon as the mains power fails and shuts off automatically when the power is restored.
So it also performs the function of an emergency lamp. The connected battery is used for powering the candle”light and it is charged continuously when the unit is not being used and powered through the mains supply.
An interesting “puff off” feature is also included so tatthe “candle” light may be switched OFF whenever desired through a puff of airinto the attached mic which acts as the air vibration sensor.
Simple Emergency Flashlight Circuit
This circuit may be used as an automatic emergency lamp when there’s no power or when mains power fails during night times.
As shown in the diagram, the circuit utilizes a cheap incandescent flashlight bulb for the required illumination. As long as the input supply from the mains transformer is present the transistor remains switched OFF and so does the lamp.
However the moment the mains power fails, the transistor conducts and switches ON the battery power to the bulb, instantly illuminating it brightly.
The battery is trickle charged for so long as the mainspower remains connected to the circuit.
Parts List
R1 = 22 Ohms,
R2 = 1K,
D1 = 1N4007,
T1 = 8550,
Lamp = 3V flashlight bulb.
Transformer = 0-3V, 500 mA,
Battery = 3V, penlight 1.5 V cells (2nos. in series)
Music operated Dancing Light Circuit
This circuit may be used for transforming music into dancing light patterns.
The operation of the music lamp circuit is very simple, the music input is fed to the bases of the shown transistor array, each of them are configured to conduct at a specific voltage level in the incrementing order from the top to the bottom transistor.
Thus the uppermost transistor conducts with the input music is at the minimum volume level and the subsequent transistor starts to conduct in sequence as per the volume or the pitch of the music.
Each transistor is rigged with individual lamps which light up in response to the music levels in a “chasing” dancing light pattern.
Parts List
All the base presets are = 10K,
All the collector resistors are 470 Ohms,
All the diodes are = 1N4148,
All NPN transistors are = BC547,
The single PNP transistor is = BC557,
All the triacs are = BT136,
The input capacitor = 0.22uF/25V non polar.
Simple Clap Switch Circuit
The interesting clap switch circuit shown here can be used in stairways and passages for illuminating the premise momentarily through clap sound.
The circuit is basically a sound sensor circuit with an enclosed amplifier stage. The clap sound or any similar sound is detected by the mic and converted into minute electrical pulses. These electrical pulses are suitably amplified by the subsequent transistor stage.
The Darlington stage shown at the output is the timer stage which switches in response to the above sound interaction and illuminate the connected LEDs for some period of time defined by the 220K resistor and the two39 K resistors.
After the time lapses the LEDs are switched off automatically and the clap switch circuit returns to its original state until the next clap sound is detected.
The parts list is given in the circuit diagram itself.
A Simple ELCB Circuit
The circuit shown here can be used for detecting earth leakage conditions and for implementing the required shutting off the mains power supply.
Unlike usual configurations, here the ground to the ELCB circuit and the relay is acquired from the earthing line itself. Also since the input coil is also referenced to the common earthing ground, the entire functioning becomes compatible and accurate.
On sensing a possible current leakage at the input, the transistors come into action and switch the relays appropriately. The two relay have their individual specific roles to play.
One relay detects and switches OFF when there’s current leakage through an appliances body, while the other relay is wired up to sense the presence of a the earthing line and switches OFF the mains as soon a wrong or weak earthing line is detected.
Parts List
R1 = 33K,
R2 = 4K7,
R3 = 10K,
R4 = 220 Ohms,
R5 = 1K,
R6 = 1M,
C1 = 0.22uF,
C2, C3, C4 = 100uF/25V
C5 = 105/400V
All diodes = 1N4007,
Relay = 12V, 400 Ohms
T1, T2 = BC547,
T3 = BC557,
L1 = output transformer as used in radio push pull amplifierstage
Simple LED Flasher
A very simple LED flasher circuit is illustrated in the diagram. The transistors and the corresponding parts are connected in the standard astable multivibrator mode, which forces the circuit to oscillate the moment power is applied.
The LEDs connected at the collector of the transistors start flashing alternately in wig wag manner.
The LEDs shown in the diagram are connected in series and parallel, so that many numbers of LEDs can be accommodated in the configuration. The pots P1 and P2 may be adjusted for getting different interesting flashing patterns with the LEDs.
Parts List
R1, R2 = 1K,
P1,P2 = 100K pots,
C1, C2 = 33uF/25V,
T1, T2 = BC547,
Resistors connected with each LED series = 470 Ohms
LEDs are 5mm type, color as per choice.
Simple Wireless Microphone Circuit
Anything spoken into the mic of the presented circuit cab be clearly picked up and reproduced by any standard FM radio, within a range of 30meters of distance.
The circuit is very simple and just requires ther shown components to be assembled and connected with each other as depicted in the diagram.
The coil L1 for this FM transmitter circuit consists of 5 turns of 1mm super enameled copper wire, having a diameter of around 0.6 cm.
Parts List
R1 = 4K7,
R2 = 82K,
R3 = 1K,
C1 = 10pF,
C2, C3 = 27pF,
C4 = 0.001uF,
C5 = 0.22uF,
T1 = BC547
40 LED Emergency Light Circuit
The shown design of a 40 LED emergency light is driven usingan ordinary transistor/transformer inverter circuit.
The transistor and the respective winding of th transformer are configured as a high frequency oscillator stage.
The oscillations induce a high voltage across the winding of the transformer. The stepped-up voltage at the output is directly used to drive the LED which are all connected in series for getting the desired balance and the illumination.
Parts List
R1 = 470 Ohms,
VR1 = 47K,
C1, C2 = 1uF/25V
TR1 = 0-6V, 500mA,
Battery = 6V, 2AH,
LEDs = high bright white, 40 nos.
Simple Transistor Latch Circuit
If you are looking for a circuit which can be used to latch the output in response to an input signal, then this circuit can be used for the intended purpose very effectively and also very cheaply.
A momentary input trigger is applied to the base of T1,which switches it for a fraction of a second depending upon the length of the applied signal.
The conduction of T1 immediately switches T2 and the connected relay. However at the very instant a feedback voltage also appears at the base of T1 via R3 from the collector of T2.
This feed back voltage instantly latches the circuit and keeps the relay activated even after the trigger from the input is removed.
Parts List
R1, R3 = 100k,
R2, R4 = 10K,
C1 = 1uF/25V
D1 = 1N4148,
T1 = BC547,
T2 = BC557
Relay = 12V, SPDT
Simple LED Music Light Circuit
In one of the previous sections we studied a simple music light show circuit using mains operated incandescent lamps, the present design incorporate LEDs for similar intended light show generation.
As can be seen in the figure, the transistors are all wired up in sequencing array. The music signal varying with pitch and amplitude is applied at the base of the buffer amplifier PNP transistor.
The amplified music is then fed across the whole array where the respective transistor receive the inputs with incrementing pitch or the volume levels and go on switching in the corresponding manner from start to finish, producing an interesting LED light sequencing pattern.
This light exactly varies its length according to the pitch or the volume of the fed music signal.
Parts list is provided in the diagram.
A Simple 2-Pin Automobile Indicator Lamp Flasher Circuit with Buzzer
If you want to make a flasher unit for you motorbike then this circuit is just for you. This simple turn signal flasher circuit can be easily built and installed in any two wheelers for the desired actions.
The automobile flasher circuit employs just two 2-pins instead of 3 as found in other flasher circuits. Once installed, the circuit will faithfully flash the side indicator lights whenever the intended function is switched ON.
The circuit also incorporates an optional buzzer circuit which can be also included for getting a beeping sound in response to the flashing of the lamps.
Parts List
R1, R2, R3 = 10K
R4= 33K
T1 = D1351,
T2 = BC547,
T3 = BC557,
C1, C2 = 33uF.25V
L1 = Buzzer Coil
Simple Relay Motorbike Flasher Circuit
In the above section we discussed a simple three transistor based flasher circuit; here we study another similar design, however here we incorporate a relay for the switching actions of the lamps.
The circuit looks pretty straightforward and employs hardly anything substantial and yet performs the expected functions wonderfully well.
Just build it and wire it in your mo-bike for witnessing the intended functions...
Parts List
R1 = 1K,
R2 = 4K7,
T1 = BC557,
C1 = 100uF/25V,
C2 = 1000uF/25V
Relay = 12V, 400 Ohms
D1 = 1N4007
Simple Door Bell Timer, with Adjustable Timing Facility
Yes this simple transistor circuit can be used as a home door bell and it’s ON time can be set as preferred by the user, meaning if you wanted that the sound of the bell to remain switched ON for a particular period of time, you could easily do it just by adjusting the given pot.
The actual tune is derived from the IC UM66 and the associated components, while all the included transistors along with the relay are configured for producing the time delay for keeping the music switched ON.
Parts List
R1, R2, R4, R5 = 1K
VR1 = 100K,
D1, D2 = 1N4007,
C1, C2 = 100uF/25
T1, T3 = BC547,
T2 = BC557
Z1 = 3V/400mW
Transformer = 0-12V/500mA,
S1 = Bell Push
IC = UM66
Timer Circuit with Independent On and OFF Delay Adjust Facility
The circuit can be used for generating delays at a desired rate. The On time of the relay can be controlled by adjusting the Pot VR1 while the pot VR2 may be used to decide after how long the relay responds once theinput trigger is fed by the switch S1.
The parts list is enclosed inside the diagram.
Simple High and Low Mains Voltage Cut Off Circuit
Are you having problems with your input Mains supply? That’s common problem associated with our input mains AC line, where a high and a low voltage conditions are quite frequently encountered by us.
The simple high low voltage controller circuit shown here can be built and installed in you house electrical board for getting a 24/7 safety from the possible dangerous AC voltage conditions.
The circuit keeps the relay and the wired appliances as long as the mains input stays within a safe tolerable level and switches the load OFF the moment a dangerous or unfavorable voltage condition is sensed by the circuit.
Parts List
R1, R2 = 1K,
P1, P2 = 10K Preset,
T1, T2 = BC547B,
C1 = 100uF/25V,
D1 = 1N4007
RL1 = 12V, SPDT,
TR1 = 0-12V, 500mA
0 – 40 V, 0 – 4 Amp Continuously Variable Power Supply Circuit
This unique work bench circuit utilizes only a few inexpensive transistors and yet delivers some truly useful features.
The feature includes continuously variable voltage from zero to the maximum transformer voltage and current variable from zero to the maximum applied input level.
The output of this power supply is also over load protected. The pot P1 is used for setting the maximum current while the pot P2 is used for varying the output voltage level up to the desired levels.
Parts List
R1 = 1K2,
R2 = 100 Ohms,
R3 = 470 Ohms,
R4 = Evaluate using Ohms law.
R5 = 1K8,
R6 = 4k7,
R7 = 68 Ohms,
R8 = 1k8,
T1 = 2N3055,
T2, T3 = BC 547B,
D1 = 1N4007,
D2, D3, D4, D5 = 1N5408,
C1, C2 = 2200uF/50V,
Tr1 = 0 – 35 Volts, 3 Amp
Simple Crystal Tester Circuit
When it comes to frequency generating circuits or rather precise oscillator circuits, crystals become a crucial part, especially because they play an important role for generating and maintaining accurate frequency rates of the particular circuit.
However these devices are prone to many defects and are normally difficult to check through conventional DMM units.
The shown circuit can be used for checking all types of crystals instantly. The circuit itself is a small transistor oscillator circuit which starts oscillating when a good crystal is introduced across the indicated points in the circuit. If the crystal is a good one, the bulb lights up showing the relevant results and if there’s any defect in the attached crystal, the bulb remains switched OFF.
Simple Current Limiter Circuit Using two transistors
In many critical applications, circuits are required to maintain a strict controlled magnitude of current through them of at their outputs.
The proposed circuit is exactly meant for carrying out the discussed function.
The lower transistor is the main output transistor which operates the output vulnerable load and by itself is unable to control the current through it.
The introduction of the upper transistor makes it sure that the base of the lower transistor is allowed to conduct as long as the current output is within the specified limits. In case the current tends to cross the limits, the upper transistor conducts and switches OFF the lower transistor inhibiting any further passage of the exceeded current limit.
The threshold current may be fixed by R which is calculated with the shown formula.
Well, I am sure there can be countless number of hobby electronic circuits that can be included here, however for the moment I could gather only these many, if you think I might have missed a few you may simply feel free to update the same through your valuable comments....
Ian says
Good day.
I need a simple transistor circuit that short circuit, or discharge a cap, when the 12 volt power supply to a timer circuit gets turned off and when the 12 volt gets turned on to the timer circuit the simple transistor circuit must open circuit the cap again. This simple transistor circuit will act as a reset circuit for the timer when the power is switched of to the timer. https://www.homemade-circuits.com/wp-content/uploads/2018/08/timer-circuit.png This is a link to the timer that i am using. The transistor circuit must short circuit the cap between pins 3 and 6 of the ic when the power to the timer circuit is switched off and go open circuit when the power to the timer is switched on again. Or is there any other easy way to reset this timer when power goes off.
Thank you.
Swag says
I have designed it below, you can try it and check if it works or not:
https://www.homemade-circuits.com/wp-content/uploads/2018/08/discharge.png
Franz Asoka says
19v to 12v without current drop?
i have laptop charger of 19V 3.42A(65W).i want to step down that 19v to 12v without any decrease in current.i need 12v 3.42+A
what is the simple way?
can i use resistors to radius voltage without current drop?
can i use LM7812C to get 12v 3.42+A
Swag says
The simplest way would be to use an LM338 based circuit as shown below
https://www.homemade-circuits.com/how-to-make-solar-battery-charger/
7812 will need much modifications therefore it may not be recommended.
Kesav.N says
Few doubts in Variable Power SupplyCircuit
Pls tell the value of R4
And both POT values ?
This circuit tested by u sir…
Bcs i need to do variable power supply with amps control…
Pls guide me sir
Swag says
you can get the details here
https://homemade-circuits.com/2012/01/how-to-make-versatile-variable-voltage.html
R4 will depend on the maximum current limit required at the output of the power supply
Swag says
yes it is a tested design, use a Darlington for T1 using 2N3055/2N2222 pair
Ryzler says
Inverter circuit.
C1, C2 = 0.47uF
How many volts?
Swagatam says
ceramic disc 50V
Charles Ervin Ayes says
What is the value of the AC input supply in Simple Automatic Emergency Lamp Circuit?
Swagatam says
220V or 120V
Swagatam says
site check
rikuduseni amanoma says
hellow sir! I am an electrical student, here in the Philippines and i know you are helpful. Im developing a device for my thesis,please help me. my problem is schematic diagram of an AUTOMATIC MIST IRRIGATION FOR MUSHROOM PRODUCTION which the objective is when it set 25 degree celcius and its attain the temperature, the irrigation will turn it ON. we are insufficient of materials here so a low cost of materials to be use sir. Im hoping for your immediate response sir because I have only less than a month free to do that thing. thank you for your anticipation.
Swagatam says
hello Riku, as per your specification the mist shower should be triggered ON when the ambient temperature exceeds 25 degrees, and trigger OFF when it reaches below this figure….I hope I have understood it correctly.
Please confirm so that I can design it for you.
rikuduseni amanoma says
exactly sir but it can adjust the temperature range weather the ambient temperature or depends the temperature needed to trigger ON.thank you for helping me.
Swagatam says
did not quite understand what you meant by
…but it can adjust the temperature range weather the ambient temperature or depends the temperature needed to trigger….
rikuduseni amanoma says
what am i trying to say sir is that the device can be adjustable the temperature range because it will be use in the mushroom house and furthermore the ambient of the temperature is changing depends upon the mushroom temperature needed to sustain. please reply to me in my gmail account sir. thank you
Swagatam says
OK you can try the first circuit from this article
https://homemade-circuits.com/2016/08/incubator-temperature-controller.html
the pot can be adjusted for achieving the desired ranges
rikuduseni amanoma says
thank you for giving me the bright ideas sir. but there is a problem, how will i know that the temperature I set could be accurate in order to know that the device is effective.
Swagatam says
the cut off will be very accurate, but first the full range will need to be set by applying a precisely known temperature on the sensor,
please continue the comment under the following article for further queries
https://homemade-circuits.com/2016/08/incubator-temperature-controller.html
jack faster says
please put a simple incubator circuit which is automatic in degree thanks 🙂
Swagatam says
will try to update it soon….
Syed Ameer Hamza Askari says
Sir i made Simple Water Level Alarm Circuit but it not works please is ki detail bata dain k is me speaker hoga ya buzzer or kitne watt ka?
Swagatam says
Syed, speaker lagega 8 ohms ka chhota wala, please see the following article for more details:
www.physics.mcmaster.ca/electronics/?page=project002.html&mode=print&type=
Syed Ameer Hamza Askari says
Sir kitne watt? Sir mene 8 ohms 3 watts ka speaker lagaya lekin circuit kaam nahi kia
Swagatam says
watt value is not important any small type will work….koi bhi chhota 1 to 10 watt ke beech me chalna chahiye
Syed Ameer Hamza Askari says
Sir mene water alarm circuit banaya lekin wo kaam nahi kar raha hay
Syed Ameer Hamza Askari says
Sir mere problem solved kar dain please
Swagatam says
sorry I cannot understand what may be the problem? you can try some circuit using IC 555
Emma Tony says
HI I WANT TO MAKE CAR BATTERY VOLTAGE MONITOR WI LE INDICATOR FROM MINIMUM 3 VOLT UP TO 12V
Zehra Jabeen says
Hi…. Can u pls giv me a small application of diode with small nd simple circuit diagram?? Pls
kamran abbas says
Hi How are you
Sir
Please tell me how can I make 24 volt low battery disconnect circate
Swagatam says
Hi Kamran, you can try the second circuit from the following article for your requirement:
https://homemade-circuits.com/2011/12/how-to-make-simple-low-battery-voltage.html
just remove the relay and replace it with your load. the 100k feedback resistor can be replaced with a 1M resistor.
also change the BC547 with a high current mosfet or a high power BJT as per the load specs.
Swagatam says
…also change the 1K with 10k resistor and the 741 opamp with a LM321
eshkariel tapiador says
Referring to the phrase:
"actually the transformer is simply not required….you can connect the LEDs directly with the battery in parallel strings."
What I have is a hand crank generator using a dc motor. It produces voltage of about 9v max and a current of 50mA max. My
plan is to use the circuit of "40 LED Emergency Light Circuit" section which would invert the 9v dc to >12v ac and then
rectify it to make it dc again and then regulate it using a 12v regulator and replace it in place of a 12v battery in a UPS.
Would that work?
I appreciate your answer a lot.
thanks a lot!!!
P.S.
As soon as it works, I will connect the hand crank generator to a stirling engine to make it automatic, replacing manual human power with autmatic heat engine power.
Next problem: How to make a high torque Stirling engine…XD…but that's out of your field of interest…so i'll take it on my own..btw…thanks again!
Swagatam says
sorry that would never work? you should have specified this before.
moreover as per the diagram the trafo needs to have 220V winding at the LEd side for illuminating 40 LEDs….
eshkariel tapiador says
Good Morning Engr. Swagatam!
I just want to ask about the:
40 LED Emergency Light Circuit section
Can you give me the specific rating of each parts if I have a:
A transformer rated @ 1A; 15v-0v-15v on sec.; and 0v-110v-220v on pri.?
And instead of 12v supply make it 5v dc?
And the rating of the output transformer as follows: Vout > 12V
e.g. 13v and above.
R1=?
VR1=?
C1=?
T1=?
C2=?
Thanks!…
Swagatam says
Good Morning Eshkariel,
the supply needs to be equal to the transformer winding voltage rating, otherwise the output will be much lower, what's your battery AH specs?….actually the transformer is simply not required….you can connect the LEDs directly with the battery in parallel strings.
Automodifications reddy says
Hie sir
I have tried making timmer circuit with independant on off delay adjust fecility,its just not working,i want a2.4 v bulb with 9 v batterie to be onn for 2 sec and off for 15 to 30 sec adjustable can u plez help me…. thznx
Swagatam says
Hi, the circuit will surely work….connect another BC547 with the lower transistor to make it a Darlington pair, this will improve the circuit response…
how can you use a 9V battery to drive a 2.4V bulb?….both the voltage levels must match..
ChrisL11 says
Hi, I was wanting to attempt to construct your LED light show circuit. The image says all transistors are BC547B transistors, does this include the PNP transistor that is attached to the speaker terminals?
I was also wondering if I could use a 3.5 audio jack instead of the speaker terminals and any ideas on how to go about doing that? I would love to exchange emails about this if you're available.
Swagatam says
Hi, the upper input transistor is a PNP transistor, remaining all are NPN.
3.5 jack input from headphone socket will also work….the base of the PNP will need a 100 ohm resistor in order to safeguard it from peak input currents.
Alternatively you can also think about the following circuit which is much reliable and accurate than the above design.
https://homemade-circuits.com/2012/03/how-to-make-simple-vu-meter-circuit-at.html
My email details are given in the contact page.
Anwar Peternak says
Hi Swagatam,
Iam from Indonesia…..
I Need Schematics For Incubator Timer with Hight Torque Motor ( DC Motor Power Window in Car).
I am trying to get a DC motor to run in two direction until it reaches the end position then stop and switch polarity so it will run the other direction when power is reapplied.
Then do the same thing at the other end.
1. timer turns power on for 1min. (7:00am -7:01am)
2. motor runs in one direction until it hits stop position, say 30sec.
3. power to motor turns off when it hits stop position and delays for the 1min. timer to end/turn off main power. also reverses polarity so that.
4. next time the main timer comes on (10:00-10:01) it dose the same thing in reverse direction and repeating continuosly
5. 12 VDC Motor Reverse (Just two cable from motor + and -)
6. Need Led Indicator for Rev/Fwd motor
Can you Help me Sir and Please E-mail Schematics to : jakarta_anwar@yahoo.com
Thank you in advance for any help. This is an important home project that needs to be 100% reliable.
Swagatam says
Hi Anwar,
The 1 min timer is not required since the stop switch will automatically reset the timer after 30sec…..the frequency timing between 7 to 10 is important…the timer has to initiate after this period each time the motor has finished its operations.
I'll try to post it in the blog….stay tuned.
rajesh rajeev says
Hello sir,
myself rajesh, plz could i know the parts list of electronic candle circuit
thnks in advance….
Swagatam says
Hello Rajesh,
it's given in the following article:
https://homemade-circuits.com/2011/12/make-electronic-candle-at-home.html
AZIZ JAMALI says
DEAR SIR
MY NAME AZIZ JAMALI FROM KARACHI PAKISTAN , I NEED 4 TO 20 MA CIRCUIT KINDLY HELP ME
THANKS
Heeran Manilal says
Hello Sir, I would like to know how I can adapt the simple current limiting circuit using two transistors for my application. I would like to connect this circuit between my main power supply and load. My main power supply is 115Vac to 230Vac. My load is 115Vac to 230Vac at 10watts. I want this circuit to disconnect the load if the load exceeds 10watts and reconnect if the load is 10watts or bellow. Please assist me with components specifications as well as what changes will I need to make if I want to change the value at which the disconnection takes place. Kind regards.
Swagatam says
Hello Heeran,
You can try the concept explained in the following article:
https://homemade-circuits.com/2011/12/make-hundred-watt-led-floodlight.html
Use MJE13005 for both the transistors and calculate the values of the resistors appropriately as per the given formulas.
Carmichael Villacorta says
Hey Sir!
We have this project at school and there should be a triac in it. I found your music operated dancing light circuit to be interesting. Uhm does it really work sir? Also can I change the lamps into LEDs, without getting rid of the triacs? Lastly, what is the wattage of the resistors?
Thanks!
Swagatam says
Hi Carmichael, yes it will work if built correctly as per the diagram…make sure to connect a 1k resistor in series with the music input capacitor at the PNP base.
The circuit is not isolated from mains so is highly dangerous to touch in switched ON position.
all resistors are 1/4 watt rated
LEDs can be used but using LEDs will make the purpose of the triacs useless
Abu-Hafss says
Hi Swagatam
Can you please suggest me a sample-and-hold circuit for at least 10 seconds or more?
Swagatam says
Hi Abu-Hafss,
I haven't studied the concept much so I am not sure whether my suggestion is correct, you can refer to the second circuit given in the following link, looks applicable to me:
easy-electronic-circuits.blogspot.in/2012/04/track-and-hold-circuits-explained.html
mallikaraja hari says
sir kindly do the necessary things
Swagatam says
mallikaraja, I'll surely include them in my blog, thanks!
mallikaraja hari says
dear sir kindly publish some simple and useful circuits for ece department with components?????
mr. green says
Dear bro i'm extreemly in need of a programable humidity controller circuit,, can u pls help me… my e-mail is – myfnf1@gmail.com
Swagatam says
Dear Bro,
please provide an elaborate description of your requirement, I'll try to help.
hui says
hii swagatam, i want ask about emergency lamp using Led, when we use a battery 6v 4.5ah as battery, zener 12v needed change / lower it ?? would it damage battery 6v ???
Swagatam says
Hi hui,
it should a little higher than the battery voltage…..so a 9V zener will be just fine.
biannz says
sir please im just asking do have a smoke or fire alarm? please if you have designed refer me the link thank you.
Swagatam says
biannz, you can refer to this circuit:
www.brighthubengineering.com/diy-electronics-devices/113566-make-a-simple-ic-741-smoke-detector-circuit-schematic-diagram-enclosed/
NITHIN KV says
Hi swagatham,
Its me Nithin from kerala , iam planning to build a simple circuit for my water tank which always overflows and makes wastage of water, i need a circuit which can trip the pump circuit main after the water level attains.so please help me to do this task by guiding me.also please provide a power supply circuit also.thanking u
Swagatam says
Hi Nithin,
You can try the following circuit:
https://homemade-circuits.com/2011/12/how-to-make-simple-water-level.html
The power can fed from any 12V/1amp ac/dc adapter.
Din D says
Hi How do I make an electronic timer cut off? eg: switch off the circuit after 3 minutes.
Swagatam says
look for 4060 simple timer circuit.
Susantha Ganegamage says
In Simple Automatic Emergency Lamp Circuit, what is the value of D4 diode?
Swagatam says
1N4007
Susantha Ganegamage says
In Simple Automatic Emergency Lamp Circuit, What is the value of C1 capacitor?
Swagatam says
105/400V
Susantha Ganegamage says
In Simple Automatic Emergency Lamp Circuit, What is the value of T1 transistor?
Swagatam says
2N2907, 8550, BD140 all these will work
Abu-Hafss says
Hi Swagatam
I want to use the current limiting circuit with a car battery, to provide fixed 5A to a load which can draw more current. Are the following values okay?
Q1 = TIP32C
Q2 = TIP127
Base resistor = 1k
Current resistor = 0.14 (wattage ?)
Swagatam says
Hi Abu-Hafss,
Please refer to this article, it has got all the details :
https://homemade-circuits.com/2011/12/make-hundred-watt-led-floodlight.html
By the way you can simply use a LM338 IC, it's internally set to produce maximum 5amps and will never exceed this limit.
achilles hector says
in:Simple Automatic Emergency Lamp Circuit
1. Can I use 12v battery?
2. Can I use 1 watt LED? What resistor value will I use?
Thanks in advanced sir!!! thanks for your answer!!!
Swagatam says
yes 12v can be used, for 1 watt led use a 33 ohm 2 watt resistor in place of D3/D4
achilles hector says
In :40 LED Emergency Light Circuit
1. Can I use 12v/7.5mAH battery?
2. And if possible, what modifications will I make?
3. How many LEDS will I use?
Swagatam says
the circuit is not very efficient so will not work with mAH batts…..use the following circuit, it's highly efficient:
https://homemade-circuits.com/2012/09/led-emergency-light-circuit-using-boost.html
achilles hector says
you mean if the power source is 12v then the transformer is 12-0-12v, and if the power supply is 6v then the XMER is 6-0-6v?
achilles hector says
how about in "Simple Audio Power Amplifier Circuit"?
1. what is the transformer, 12-0-12v or 6-0-6v?
2.in 100E 5WATTS, what does "E" stands for?
3. Can I use a speaker with
impedance: 4 ohms
rated input: 1.6 watts?
by the way thanks for all the answer you gave me!!!!!!!your the man!!!!!!!!!!!! 🙂
Swagatam says
1. transformer V rating should be be equal to the supply voltage
2. E stands for Ohms
3. yes it can be used.
You are most welcome Achilles
achilles hector says
40 LED Emergency Light Circuit
Swagatam says
trafo is 6-0-6V, R1 = 470 ohms
achilles hector says
the emergency light with invertrer
Swagatam says
pls show me the link, because there are two emergency circuits in the above article.
Jinnamuru Xunte says
good day sir!
I have a question for you.
1. Is the transformer 's secondary a 6-0-6v or a 3-0-3v
2. what is value of R1
Swagatam says
which circuit are referring to?
Mohan says
Sir for the 'SIMPLE CURRENT LIMITER CIRCUIT USING 2 TRANSISTORS' which you had posted here. I want a quick reply sir
Swagatam says
You can refer to this post and calculate yourself as per the given formulas at the end of the page:
https://homemade-circuits.com/2011/12/make-hundred-watt-led-floodlight.html
Mohan says
Sir, what will be the wattage of resistor for 5 A maximum load current in the current control circuit ???? Will this circuit be able to handle such high load???
Swagatam says
Hi Mohan, for which circuit?
sidra masood says
can i ve working of emergency lamp ckt ?
sidra masood says
can i have working of emergency lamp ckt
Anonymous says
in "Automatic Day Night Light Switch Circuit" please tell me the wattage of the resistors, thanks
Swagatam says
1/4watt CFR
sat says
value of R2 missing in 40 LED EMERGENCY Light
Swagatam says
10 ohms, 1/4 watt
syphou seng says
circuit good
Anonymous says
hello sir , i want circuit which can run a single DC motor in clockwise and anticlockwise direction……also i want to know which type of relay should be used in toy car for movt left and right……
Swagatam says
It's not just about relay, it's much more complex, you can refer to this post:
https://homemade-circuits.com/2012/09/make-remote-controlled-toy-car-circuit.html
shadab says
hi I am Shadab , I think you remembered me.
I have got a science congress in my school so, I was searching for non polluting batteries just like air battery, earth battery etc.
Do you have any other type of battery or do you have any capacitor related project or circuit as battery.
please please……….
thankx
Swagatam says
I am sorry, presently I do not have any info regarding such batteries.
Anonymous says
Could someone post a battery eliminator circuit.
I need to eliminate 2 AA cells which would be 3.0Vdc with clean DC power.
It is in an audio circuit so no ripple. I suppose I could try a wall wart DC power supply, but I would want to make sure it is good clean DC so no ripple is injected as it is an RTA device.
Anonymous says
Hai sir
I have a 6v 4.5ah lead acid battery.then what are the changes reqierd the automatic emergency light circuit
Swagatam says
Remove D3, D4 and connect the battery directly to the shown position, no changes would be required.
zenilyn dimapilis says
,.good evening,sir! i just want to ask for help. i'm needing for a simple circuit that uses a sensor, which we can use in everyday living, yet the materials are affordable. hope you will respond! thanks in advance! 🙂
Swagatam says
what kind of sensor are you looking for? Please provide more details about it.
zenilyn dimapilis says
,.any sensor will do,sir! ahm, is there any "plastic materials sensor" sir? i just thought of a circuit which can separate wastes (biodegradable from non-biodegradable)… is this possible? can you help me create a circuit like this? thankyou soooo much,sir! good day! 🙂
Swagatam says
I am sorry, Such a circuit would be difficult to design at my level, because there's no sensing element available in the market specified for distinguishing biodegradable from non-biodegradable
Swagatam says
you are welcome Zenilyn, keep posting.
tech. eduard says
Hi mr. / swagatam what is the volt of 0.47uf in the circuit 100 watt inverter
Swagatam says
It's 50V.
tech. eduard says
Sir what polarity in R5and R6 negative or positve
Swagatam says
R5 R6 are resistors and resistors don't have polarities.
tech. eduard says
I mean sir in 100 watt transistor base inverter
what polaritie of 0.47uf cap. They can top to R5 and R6 . Positive/ negtive.?
2nd quiz.
What type of transistor T4 ,T5 PNP or NPN they can buy.,if sold out to the market transistor # TIP 127 what transistor they.?
Swagatam says
Please refer to this post, you will get a better picture of the design:
https://homemade-circuits.com/2012/07/simplest-and-best-100-watt-inverter.html
0.47 is a non polar cap.
use BD680 in place of tip1237, they a PNP transistors.
Anonymous says
good day sir! do you have a fm transmitter circuit with a 30 to 60 meter range?
Swagatam says
search for "wireless speaker" in the search box, the relevant circuit will provide that much range….
Anonymous says
hi
can you tell me how all the components work in simple automatic emergency lamp circuit?
samshadnc007 says
Hi
Let i want to know about simple electronic circuit creating application for my windows 7
Anonymous says
Can U please let us know the values. Of capacitor c1 and diode d2 in the circuit simple emergency flashlight
ruben3571 says
i would like to know the value of P1 and P2 on 0-40 volts/0-4 amps adjustable power supply… thanks in advnce
Swagatam says
please refer to the following post:
https://homemade-circuits.com/2012/01/how-to-make-versatile-variable-voltage.html
raju roy says
How to use TL2N2219A TRANSISTOR in Wireless Microphone Circuit.
Swagatam says
Google it…
ivan dela cruz says
what did you mean by setting the capacitor values appropriately?i will change the value of the capacitor the you gave in the parts list?what type of capacitor will i use?mylar?is the TIP there is an oscillator?
Swagatam says
calculate the capacitors appropriately which would provide you 60Hz….refer to this link to know more:
www.electronics-tutorials.ws/waveforms/astable.html
ivan dela cruz says
tnx swagatam, in the site that you've given, is it possible that we will not change the value of capacitor but rather change the value of resistor?by the way, what is the value of R7 and R8 in the circuit?
ivan dela cruz says
excuse me sir swagatam, is the blue line in the 100w transistor based inverter is the positive?
Swagatam says
yes it's the positive line.
Swagatam says
transistor base resistors can be changed instead of the caps.
R7, R8 = 22 ohm/ 5 watt
ivan dela cruz says
what capacitor should we use?mylar or electrolytic?if electrolytic what is the positive and negative side their?
Swagatam says
mylar will do
Swagatam says
yes it can be done by setting the capacitor values appropriately.
ivan dela cruz says
thank you! another question swagatam, is the output of this inverter can reach 60Hz?
ivan dela cruz says
hi swagatam, in the 100 Watt Transistor Based Inverter Circuit is the output a sine wave?
Swagatam says
Hi Ivan,
it's square wave.
arun kumar says
hello ! bro
Thanks for what you done for whole circuits i am an engineering student ……….i want a different project from all which can impress my teacher well………..to get max marks i need some more information ………….
Zia-ur Rehman says
Hi swagatm
Pls tell me, which typr of transistors are used in "Timer Circuit with Independent On and OFF Delay Adjust Facility"
Swagatam says
Hi Zia,
the transistor numbers are given in the diagram.
AZIZ JAMALI says
AZIZ.JAMALI@YAHOO.COM
AZIZ U REHMAN
GOOD CIRCUIT
ivan dela cruz says
what capacitor did you use?a ceramic or an electrolytic?
Swagatam says
electrolytic….
ivan dela cruz says
good day swagatam i would like to as for the 100 Watt Transistor Based Inverter Circuit is the output a sine wave?
Anonymous says
good day sir! i tried the music led circuit and it is only blinking! what am i supposed to do?
Swagatam says
adjust the presets so that each subsequent led illuminates at rising levels of the music
Anonymous says
each presets ? or i will adjust all presets with the same value?
Swagatam says
each preset a little differently…..
Anonymous says
SIR , CAN YOU DO ADDITIONAL IMPROVEMENTS, I MEAN ADD SOME ADDITIONAL FUNCTIONS TO THE CIRCUIT "Simple Water Level Alarm Circuit", COZ WE ARE ASKED BY OUR INSTRUCTOR TO IMPROVE A CERTAIN CIRCUIT, THANKS IT WOULD BE SUCH A GREAT HELP IF YOU COULD DO IT FOR ME 🙂
Swagatam says
I have many interesting water level controller circuits in this blog, just type "water level controller" in the search box, you will find all of them and will be able to choose the best one for you.
Anonymous says
hi swagatam. nice diagrams.. but can u redraw the Simple LED Music Light Circuit with speaker on it?? please..
mail me pls sir..
cepada_aj@yahoo.com
Swagatam says
It won't be feasible presently due to lack of time, but i'll try to do it soon in the near future
Anonymous says
SIR please tell me the details of following components in
Simple Automatic Emergency Lamp Circuit.1. transistor 2. c1 3.watts of resistors.
Swagatam says
resistors are all 1/4watt, transistor = BD140, C1 = 0.68uF/400V
Anonymous says
good day sir, for the Simple LED Music Light Circuit, what is the value of the PNP transistor?i used to do it but it only light the LED. .i used 1K preset. .
Swagatam says
you can use a BC557.
Sumant dev says
sir ,one thing more i want 2 know that does this fm Tx require antenna or not ?if it requires then plz tell me location of it.Thanks
Swagatam says
yes antenna is required, connect a small wire at the collector of the transistor.
Sumant dev says
sir, in your fm tx what will b the frequency on which it will transmit?
Swagatam says
in the standard FM band reception range.
Bual, June Vic says
Sir its me again in Simple LED Music Light Circuit what do you mean by 1k presets? is it a resistor? sorry sir for the disturbance sir im still a beginner
Swagatam says
1K preset is a variable resistor whose resistance can be varied by moving its mechanism….
see it here:
evelta.com/image/cache/data/Other%20Components/1K%20ohm%20Preset%20(Variable%20Resistance)-700×700.jpg
Bual, June Vic says
is it possible to replace the presets? into a 1k potentiometer?
Swagatam says
yes it's possible but it would find it hard to keep them stable.
Bual, June Vic says
1k ohms resistor? possible or not?
Swagatam says
do it in this way….connect 1K for the first transistor, 2.2k for the second, 4.7k for the third, 5.6k for the fourth, 6.8k for the fifth and so on….
Bual, June Vic says
last question sir ! a trimmer is it possible? im very sorry bcuz im sooo annoying
Swagatam says
By trimmer do you mean a preset? trimmer normally is associated with a variable capacitor which will not work here…..only a variable resistor will work, or do as I have suggested in the earlier comment.
Bual, June Vic says
sir to the speaker terminal. it requires audio jack it has a three terminal
Swagatam says
use the big terminal and one of the small terminals.
Anonymous says
thank u v much
Anonymous says
hello swagatam,
please what is the workind operation of
Simple High and Low Mains Voltage Cut Off Circuit. what functions do the various component perform to carry out the operation. pleae i need your help
thank u
Anonymous says
hello swagatam majumdar,
i need to build wireless intercom of range 15 meters.
help me out.
thank you
Swagatam says
Presently I don't have one, i'll try to find it, and inform you….
Abu-Hafss says
I tested the circuit with various configurations (different resistors and transistors) on LTSpice and Falstad's applet, the results were positive. One thing I noticed that the 2 transistors should be complimentary of each other. I mean, BC557+BC547 or 2N4403+2N4401 would work, BC557+2N4401 or 2N4403+BC547 would not work. Physically, I have tested with BC558+BC547.
Swagatam says
If the circuit would work with complementary pairs it would work with non complementary pairs as well, as long as they are NPN/PNP.
There are many types of similar oscillator circuits on the net, you can try a different, more feasible type of configuration.
Abu-Hafss says
Hi Swagatam
Please follow the link below to LTSpice schematic file, showing a flasher circuit:
https://dl.dropbox.com/u/20969135/Flasher%20OK%20-%20B%20-%20Square.asc
The simulation is working fine. Even it is working fine with FALSTAD's applet simulator. But when I assembled the components physically, I got constant voltage across "Rload".
Can you please guide me, what could be the reason.
Swagatam says
Hi Abu,
I am not able to see any circuit in the given link.
Abu-Hafss says
Ah yes, you won't see the circuit there. You will get the netlist of the simulation. Simply go to the file menu and save it and then run it in LTSpice. Or for your convenience, the image of the circuit is attached here
https://dl.dropbox.com/u/20969135/Flasher.png
Swagatam says
The circuit should oscillate, try adjusting the value of 470K resistor…use a 470 K pot instead with a 1K series resistor.. adjusting this might help to initiate the flashing action.
Abu-Hafss says
I have replaced 470K with 500K POT but no result. Only the light turns ON or OFF. Similar result when replaced 330K with 500K POT. 🙁
Anonymous says
HI mr swagatam!! a hav a question regarding the LED music light circuit, how and where can we input the music,,?? are the terminals for the speaker indicated in the diagram is for the jack of a cellphone device or something/??
please reply i need the project urgent!!! THANKS!
Swagatam says
Yes a cell phone jack output can be used.
Connect a 47 Ohms resistor in series with the emitter of the first music input transistor for safeguarding it against high pitched music.
Bual, June Vic says
Sir Swagatam in the dancing light circuit it is possible to change the bulb in to led? and remove the triac?
Swagatam says
Hi Bual,
Yes it is possible, you may connect an LED with resistor across the transistor emitter diode and ground.
Bual, June Vic says
Sir Swagatam! in clap switch is there any kind of mic use? or just electret? bcuz i try this circuit using electret but it is not working
Swagatam says
Hi Bual,
Yes a condenser mic has been used at the input.
You will need to connect a small coil also of may be 100 turns of 0.1 mm copper wire across the base of the PNP transistor and positive to make the circuit stable and failproof….
Anonymous says
sir, gud morning i do the "simple LED music project" but it does'nt work.. i change the dc input to see if there is an output to my project but still the same,, what would i do? i really need your help…
Swagatam says
Apply music with loud volume and check the voltage at the collector of the first PNP transistor….it should be create peaks equal to the supply votage
Anonymous says
sir, its me.. the guy asking about the "simple LED music project".. can i used NPN on the first transistor? .. and can i add 5 led lights by making it parallel to each LED light?
Swagatam says
No an NPN transistor won't work for the input transistor.
4 LEDs can be added on each channel…
Anonymous says
Nice site sir Mr. .. Electronic circuits useful … Congratulations case to you thank you very much for this wonderful work …Do you find when you electronic circuit measuring humidity? Incubator eggs I want the circuit as easy as I want a metal detector circuit
With you brother David from Algeria
Me great honor to get to know you
Excuse mistakes because I am not the best English
I relied on the Google translator to talk to you
tda1558@yahoo.fr
Swagatam says
Thanks very much David,
You may refer to the following link which shows an easy relative humidity sensor circuit, you will have to replace the LED with a 0-10V voltmeter or any other suitable type for reading the results:
www.gophoto.it/view.php?i=www.electronicdesign.com/files/29/1684/figure_01.gif#.UNlsHuTCbTo
Anonymous says
still getting same problem after removing LED and yes speaker producing buzzing sound
Swagatam says
If one end of the capacitor remains unconnected the circuit cannot oscillate and buzzing cannot happen, remove the capacitor entirely and now see if the speaker still buzzes or not.
Anonymous says
the capacitor is already isolated
but one modification i have done in the ckt is i used led(positive end with collector of t2 and negative with battery). and it illuminate as i connect the battery.
Swagatam says
Remove the LED and see what happens, by the way is the speaker producing a buzzing sound…?
Anonymous says
sir i have made water level circuit
but when i touch the two wire which are inside the water only then it make sound and it happens in air also
i use the same component as given above
can you tell me what is the issue?
Swagatam says
The circuit will not make any sound if the two wires are not in contact….there must be some leakage in the PCB, keep the capacitor external pin completely isolated from speaker wire.
Anonymous says
then what model of bjt should i use for t2 because 8550 is not available in the market (near to me)
Swagatam says
You may use a 2N2907 or BEL187
Anonymous says
helloo sir..
can i use bc 547 in water alarm ??
Swagatam says
for T1 it's OK but not for T2….
Anonymous says
hi swagatam…
iam making the project on temperature detector ..i want to know
what source should i use for heating
and is this circuit working or not???
Swagatam says
You can use a 40 watt incandescent bulb as the heat source……….the circuit is perfect, it works.
Anonymous says
thanks…
but there is a confusion ..the preset use in the circuit is connected with its all three terminals…and as far as i see only last or first two terminals connected in any circuit..
but in this ckt base is connected with middle one terminal of preset
is it???
Swagatam says
It depends on the type of application, here all the three pins are required to be used, otherwise the circuit cannot be set properly.
Vinod KC says
Hi Swagat,
Please post this 100w inverter circuit once again. Because this image is not clear. And i request you to post an inverter circuit with 12v 7Ah battery.
Anonymous says
sir in the simple automatic emergency lamp
1.sir which terminal of capactior c2 will be connected to diode d1?
2.which battery sal i use a 9 v 6F22 battery or a 6v 4.5 amp lead acid battery??
3.if i donot connect the ac supply will there be any problem?
if no where sal i connect those two free ends
Swagatam says
longer lead of C2 will go to D1
use 9V battery only.
If you do not connect AC, leave the ends free.
Anonymous says
if i use a 12volt battery??
Swagatam says
for 12v supply you will have to connect a 330 ohm resistor with each led string.
Anonymous says
thank u sir!!!
i hav succesfully completed that circuit!!!
Swagatam says
That's great….!!!keep it up.
Royal Raja T says
hello sir i successfully done that light… thank u
Swagatam says
That's great….congrats.
Royal Raja T says
oh thankq i'll inform u wen i finish that project….
Royal Raja T says
Hi sir can i know the value of C1 and D4 of Simple Automatic Emergency Lamp Circuit
Swagatam says
Hi Raja,
all diodes are 1N4007 and C1 = 0.47uF/400V
Anonymous says
so i can use a 1000 uF in place of c1??
and rest all equipments remain the same?
in the simple automatic emergency lamp
Swagatam says
I think I am getting confused with the above questions….in LED emergency light circuit C1 = 474/400V or 684/400V and all the diodes are 1n4007
Anonymous says
okk okk i got u.
Anonymous says
its about 1.5 cm *1 cm size…
rectangle type….
Swagatam says
I think they have provided you with the right part, try it.
Anonymous says
okk thanks
Anonymous says
wats the value of d4 and c1 in simple automatic emergency lamp
Swagatam says
C1 = 474/400V(0.47uF/400V)
All diodes are 1N4007
Anonymous says
thank u sir
Anonymous says
and the value of t1??
Anonymous says
can i replace the t1 and t2 with any other transistors in the water level alarm circuit ??
Anonymous says
sir i asked for that capacitor and the shop owner gave me a capacitor having a written on it as 474kw TL250vE
is it corrrect?
Swagatam says
BD140…..or you may also try 8550, 187, or 2N2907
Swagatam says
all diodes are 1n4007, C1 = 1000uF/25V
Swagatam says
what is the approximate size of the capacitor?? I am not able to guess from the written value….
Anonymous says
sir in the automatic emergency lamp circuit wats the value of c1
Swagatam says
0.68uF/400V
Anonymous says
thanks swagatam
Anonymous says
in that water level alarm wats the value of 0.1 ceramic capaeitor?
is it 0.1 f or 0.1 microfarad
Swagatam says
0.1uF (microFarad)
Anonymous says
sir can i cnnect a number of leds parallel or series to each other in ac supply directly………..
if yes hw many leds shall i use and series or parallel?
Swagatam says
Mains AC is never stable and involves high current, so you can't use LEDs directly on them, they will simply blow of with minor voltage fluctuations.
Swagatam says
No you cannot connect two 7805 ICs for getting 10V, you will have to use 7810 IC for that.
You can connect 3 LEDs in series without using a resistor in a 10V supply.
Anonymous says
can i use 23A005 ic for 20 volt productiona dn then connect 6 leds in it!!!
Swagatam says
23A005 is NOT a voltage regulator IC, it's a transistor, so you cannot use it.
Ashish says
sir if i use a voltage regulator ic which will provide me a constant 5 volt supply and if i connect two such ic then i will be geting 10 volt supply
then without using any resistors how many leds can i connect there?
and will there be any problem in such a cicuit?
charu jain says
Hi.
If in automatic day night light switch circuit, number of lights increases, do the value of any of the component changes? n can u please explain how the circuit works?
Swagatam says
Hi,
The circuit utilizes a relay whose contacts have no direct connection with the circuit, so the number of lights will not affect the circuit in anyway, you may use any number of lights, but the wattsge shouldn't exceed the max relay contact rating…
Anonymous says
Hi swagatam,
i do not understand the mechanism through which the circuits operate,although i repaired some faulty things but only through component testing with only 40% of success not knowing what is actually going on in the circuit.Can you please help me to suggest things so that i may learn electronics in detail.
thanking you.
sahil sehrayi
Swagatam says
Hi Sahil,
I'll try my best to help you in the field….
VINAY H says
Hi, Sawagatam,
I need circuit digram for 3 Volts SMPS
Anonymous says
Hello swagatam,
what software are you using in drawing your schematic diagrams in electronics? where can i download it?
By the way, I'm Jeff, my hobby is building simple and useful electronic circuits.
thanks!
Swagatam says
Hello Jeff,
Welcome to my blog!
I don't use any software, I do it on corel-draw.
Regards.
Anonymous says
hello swagatam,
please update the site with the 5km FM trasmitter and reciver.
Swagatam says
Hello friend,
I'll surely do it someday, for the time being you may refer the following link:
electronics-diy.com/tx500.php
Hararion says
hello i need the current limiter circuit to operate a sensitive pendulum circuit, so i need some advice with the current limiter circuit
1) the value of the brown-orange resistor
2) the reference of the transistors
3) this circuit can be used to limit a current in a single AA battery?
is to power up a small electronic pendulum circuit, this was originally designed to work with a 2V solar cell, but when i connect a single AA battery, the circuit is saturated then the pendulum stops moving…
any help could be appreciated.
Swagatam says
Hello, thanks for inquiring, however without seeing the application details it will be difficult for me to assess the correct circuit for it, so if you can give me all the technical details about your needs then probably I can help….
Sam says
really cool circuits for a budding hobbyist 😀
Swagatam says
My pleasure….
Anonymous says
REALLY GOOD CIRCUITS
Swagatam says
Thank you!
pp says
Hello Swagatam..
Thank you for kind & quick replies..
Actually in 40 LED emergency Light..the value of T1 and R2 is not mentioned… and I would like this emergency light should be ineffective during day time to save battery power, as I have 12V batt., in the diagram 6V Batt is used…will this same circuit work on 12V Batt.
I request you to please do needful modification particularly in this circuit diagram…so I can start with it…
Regards,
Swagatam says
Hi PP,
I'll design a new circuit with all these specs soon and inform you when it's posted.
Regards.
bepv says
0 – 40 V, 0 – 4 Amp Continuously Variable Power SupplyCircuit R4 PLEASE
Swagatam says
R4 = 0.1 Ohms, 5watts, for 4 amps max.
Javed Anjum says
Hi Swagatam,
All Simple and useful Circuits.. Thanks a lot, God Bless you.
MJA
Swagatam says
You are welcome Javed!
pp says
Hello..Swagatam..
40 LED Emergency Light Circuit, How can we add auto cut off Batt. charger circuit and the stepdown transformer 6-0-6 V 500mA it's need to be connected other way round..???
Swagatam says
Hi PP,
You will need a separate transformer/rectifier circuit for charging the battery. A low battery cut-off will require another circuit, I will try address a suitable low voltage battery cut off circuit soon through one of my articles.
pp says
Hello..Swagatam,
40 LED Emergency Light Circuit
Thanks for Quick reply..of my query you've replied for first part, The Transformer 0-6v 500mA is connected for LED's to be lit..how much AC Voltage all LED's will get…and backup will be of how much time???
If you are updating the above mention circuit….Please !!!
I would like to give it a try…
Regards
pp says
…and what is the value of R2???
pp says
…and value of T1..Is it purposely not mention the value of some parts???
savyasachi says
Hi swagatam..,
I need a water level detecting circuit which turn off a relay and the circuit itself when the plastic water tank gets full of water.
Swagatam says
Hi Vinod,
Yes we can easily make it by doing a little modification in the circuit shown in the above post.
I'll try to post the idea soon.
tech. eduard says
Hi good ev sir swagatam what volt of capacitor 0.47uf in 100 watt transistor base inverter
Utsav says
Could you tell what is the value of R7 and R8 in the 100 Watt Transistor Based Inverter Circuit?
Please answer.
HECANET says
Good job man. Keep the flags flying. One little observation though, the 100 Watts amplifier seems to be missing a few key resistors. Look at the bases of T10 and T14 and confirm that is exactly what you intended. T14 for instance, the base and emitter are both tied to the negative rail. Similarly, T10 has its base and emitter tied to the positive rail. This configuration is a diode configuration and the circuit will hardly work as an amplifier (being the final stages of the amplifier). I believe you need some resistors there.
Swagatam says
Thanks very much! I Appreciate your interest.
Actually The circuit was taken from elecktor electronics magazine and also has been tested by me practically. My prototype worked exceptionally well, so I am a little confused….
tech. eduard says
Yah i w8 your refly because need for my project what the value of R7and R8 in the 100watt transistor base inverter circuit
tech. eduard says
Hi what is the value of R7 andR8 in 100 watt transistor base inverter circuit
tech. eduard says
Hi
tech. eduard says
Hi
tech. eduard says
What volts of capacitor in the transistor inverter