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The following circuits were requested by the users through the above forum. If you have any specific requests, please feel free to post them through the forum platform.

TL494 inverter circuit




Digital Voltmeter Circuit, presented in response to the request from one of the readers.

The range of this volt-meter is from 0-2000V AC/DC



Simple Modem DC UPS circuit requested by Mr. Galive.




How to Replace IR phototransistor with LDR for identical output response.

Requested by Mr.Avishek




The following circuit was requested was Mr. Mike (see comment for circuit info):




Triangular Wave to Sine Wave Converter Circuit



Op Amp using BJT NPN, and PNP transistors





How to charge batteries individually through separate chargers while being connected in series.





Request: Sir i want to make such a controller that, it should be turned on/off as per the one given in this article. In addition to this there should be a facility to turn off the motor on power failure, since i am using a 300 W inverter to power up the ac mains. Normally the inverter comes active on power failure by changeover circuit. So i want to make sure that the motor shouldn't be run on that period even the water level goes down, to save the inverter from damage. Can you please suggest me a design SIR ?

Design:





Auxiliary battery back-up circuit



Car Door Optimizer Circuit for Mercedes SLK



Simple DRL Flasher Circuit


 
Three Phase to DC converter circuit




                                   
Blown fuse indicator circuit











Single Phasing Preventer Circuit








Diagram for 2-digit pulse counter


Ramp Generator






Generating sine equivalent PWMs by comparing a sample sinewave and a high frequency triangle wave:


IC 555 astable






IC 555 Monostable






Current controlled Load











Another programmable timer circuit can be seen below using IC 4060 and IC 4017

The described circuit was originally designed as a long duration timer circuit, however the design can be effectively employed for achieving a 2 way independently programmable timer circuit



Parts List

R1, R3 = 1.2M
R2, R4 = 15K,
C1, C2 = 1uF/25V,
D1, D2 = 1N4007,
IC1 = IC 4060,
IC2 = IC 4017,
T1 = BC547,
POT = 1M linear
RELAY = 12V SPDT

As can be understood, each pulse from IC1 causes a sequential high logic shift across the outputs of IC2, starting from pin#3 and ending at pin#11, and then back to pin#3.

At power ON, the high logic is at pin#3 of IC2, now as IC1 generates its first pulse, IC2 responds to this and its output high logic shifts from its pin#3 to pin#2, with the next pulse it shifts from pin#2 to pin#4 and so on until it reaches pin#11.

Now suppose the pulses from the IC1 is set to have a delay of 2 hours, that implies the logic shifts across the IC2 output will also happen at the rate of 2 hours, meaning to complete the shifts from pin#3 to pin#11 would take as long as 2 x 10 = 20 hours.

How to Program the above Design for different relay ON/OFF cycles

We can see that the relay is connected at pin#11, this would enable it have a constant ON/OFF delay timing, if the other BC547 was not there.

However with the inclusion of the other BC547 makes it possible to enable the relay to have independent ON/OFF delays, depending upon at which pinout the other BC547 is attached to.

Need Help? Please leave a comment, I'll get back soon with a reply!

Comments

  1. Hi! Swagatam,
    Your site is excellent and the way you solve the queries is excellent. Recently I had problem with my door lock of my car(Wagon R, maruti suzuki) when I dismantled the lock mechanism I found that the wafer capacitor in series with the 12V DC motor had failed so tried to find the capacitor replacement but all in vain as it was made in china and the marking on it was X075 so none of the retailer could help me. Can you help me to find the value of the wafer capacitor that should be connected in series of 12V D.C motor of the door lock as, i think, protects the motor during the acceleration of the car?

    ReplyDelete
    Replies
    1. Hi Vikram,

      Thank you very much, you are most welcome!

      I don't think the problem is due to the capacitor, because it is placed just for absorbing the transients during locking and unlocking.

      The car acceleration cannot affect the central locks because these devices remain switched off until we operate them through remote or the keys.

      If at all the capacitor is causing the problem, may be due to an internal short circuit, it can be replaced by any standard value, say for example a 0.47uF/100V will do.

      By the way did you try operating the locks without the capacitors? If they still don't work, the problem surely is somewhere else and not with the capacitor.

      Regards.

      Delete
    2. hello sir swagatam its me waseem khan 4rm pakistan
      why we use relay in stablizer???? looking for ur quick responce
      Regards;waseem khan

      Delete
  2. Thanks! for the prompt reply, I really appreciate it. I am operating the car without the capacitor that was the reason I was so worried. I did not tell you about the carbon deposits on the carbon brushes as my query was getting too long, regrets!. Now I shall put the capacitor, as per your advice, in series to avoid any transient.

    ReplyDelete
  3. Hi Guys,
    I Have a Device which opeates on battery of 5 volt (i dont know current)
    I going to connect adapter cable directely to the points where battery is connected to device , Is it correct ,what will be effect on device.........

    ReplyDelete
    Replies
    1. Yes it may be done only if the adapter voltage is also near about 5 volts. Also, be careful with the polarity while connecting....

      The device will work normally if done as explained above.

      Delete
  4. Hi swagatam

    i am beginner in electronics ,i found this site first time ,its really nice .
    i wants to build my own wireless door bell ,just 50m range but dint find sofar on net ,pl help me

    ReplyDelete
    Replies
    1. Hi Unknown,

      Thanks!

      You have selected the most difficult circuit to begin with, even I haven't tried this circuit because of its complex configurations.

      You can buy a readymade one and study how it's done, presently I do not have any of my own designs.

      Delete
  5. Hi great enginer

    I am mechanical engineer and now,are working on machine for concrete making.i am in the middle of big problem,my machine has four 3-ph induction motor rated from 3 to 7.5 hp and now they must work with 1-ph source,i have decided to completely design all circuit that needed for stabilizing and rectifying and then pwm section for driving 3-ph motor,i built this circuit for low power 50 watt motor and my biggest problem is that what must be conciderred in this circuit when they have to work in such high power condition,if you agree, i could upload my progress in this project and meanwhile use your knowledge and skill in my project

    is it possible?
    thanks

    ReplyDelete
    Replies
    1. Hi ESD,

      Is your circuit working OK, I mean have you tested it with the motors.

      You can upload the circuit image here:

      http://imageshack.us/

      After uploading just send me the link, I'll try to figure out the design and give you the feedback.

      Thank you great mechanical engineer, I appreciate your response:)

      Delete
  6. Wishing You and Your Family a Very Very Happy DIWALI Swagatam Bro

    ReplyDelete
    Replies
    1. Wish you the same Bro, take care and have a nice day....:D

      Delete
  7. hello sir, i have dought on trnsistor is it tow pin tra sistor or three pin transistor ?

    ReplyDelete
  8. hello sir, is it twp pin transistor or three pin transistor ?

    ReplyDelete
    Replies
    1. transistors are always three pin and not two pin...

      Delete
  9. thanks bro by the way what is the value of R1 on the second circuit

    ReplyDelete
    Replies
    1. Hey bro,

      I told the value in my previous comment, I hope you got it....

      Delete
  10. hi Swagatam....
    i used to have nokia n79 which had a in-built FM transmitter(it used to transmit music over the FM range so that all near-by radios could receive it.... it was awesome feature). now i own a different device. can you make a FM tx so that i can connect it to my phones audio out and use it as a FM tx????

    ReplyDelete
    Replies
    1. Hi Nikhil,

      That's indeed an interesting ad-on to have with a cell phone. I think I already have one such circuit posted in this blog, you may refer it here:

      http://homemadecircuitsandschematics.blogspot.in/2012/01/how-to-make-wireless-speaker-system.html

      Regards.

      Delete
  11. Thanks its a excellent idea....


    Will it respond as quickly as photo transistor.......
    Because i am measuring velocity of pellet having 400-800 Feet per second,
    means response should me .oo125 seconds........

    ReplyDelete
    Replies
    1. You are welcome,

      Yes the LDR will respond to any switching speed because it's just responding to the shadow, acually it's the transistor which needs to be fast and BC547 can take upto 100Mhz frequencies, so no issues.

      Delete
  12. One more question,
    This LDR will response in IR light
    or they will respond in Normal Light...

    ReplyDelete
    Replies
    1. NO the LDR will not respond to IR lights, the IR leds should be replaced with white high bright LEDs.

      Delete
  13. Please Guide me To build a Compact chronograph without PC interface....
    May be using a multimeter frequency

    ReplyDelete
    Replies
    1. I'll try to design it soon, will inform you when it's posted.

      Delete
  14. Dear Swagata,
    Today I have find INFRARED Transistor TSOP11236
    But These are having 3 Pins,
    Will you suggest a circuit by this ,Instead of LDR,So that natural light will not have any interface......

    Thanks,

    ReplyDelete
    Replies
    1. It's difficult to connect a three lead sensor with the given circuit...not feasible, it won't work properly.

      Delete
    2. it can be done using transistors with the sensors, i'll try to post it here soon....

      Delete
  15. Hi Swagatam i am confusing to checking voltages in 415V Ac/110v DC Float cum boost charger. this unit contains 415/125 v transformer this transformer output connected to controlled bridge. bridge AC input 125v but voltage across the bridge +ve and -ve terminal is 30V shows my voltmeter same time i check the final charger out put 120v DC. kindly explain how it is possible.

    Note:- this bridge have 3 thyristor 4 diode (1 diode for freewheeling)

    ReplyDelete
    Replies
    1. Hi ஜெயம்,

      It's a buck charger because i's reducing the voltage.

      It will be difficult for me to understand the functioning without seeing the actual circuit and the test points you are referring to.

      You will have to study the parts which are there in between the bridge output and the final output, remove them one by one and check the results, you will be able to trace out the reason.

      Delete
  16. Hi, I have a PIR sensor that can control the brightness on a lightbulb, the PIR sends a signal between 1-10volts, 1volt is 10%, 2volt is 20% and so on. I want to use this, to control a 230vac lightbulb..

    But how?

    Thanks Kim

    ReplyDelete
    Replies
    1. Hi, you may feed the voltage from the PIR to pin#11 of the following 556 pwm generator circuit:

      http://homemadecircuitsandschematics.blogspot.in/2012/12/make-this-ic-556-pure-sine-wave.html

      The output from pin#9 may then can be used to control a triac/light bulb connection.

      Delete
    2. happy Sunday Sir. i built the water level controller, i used a 20amps relay to energize a 10amps contactor for a 1.5hp pump motor and 12v 500ma transformer. but the circuit got blown up within 3weeks, am suspecting the power supply system, so what do i do to avoid this happening again. thanks

      Delete
    3. Thanks,

      which circuit are you referring to?

      Delete
    4. the circuit of Wednesday 14th December 2011 from this Link file:///C:/Documents%20and%20Settings/James/Desktop/WATER%20LEVEL/water%20level/water%20lev_files/how-to-make-simple-water-level.htm. thanks

      Delete
  17. Dear Swagatam Majumdar

    I have a dc motor drive. For controlling motor speed there was a 10k ohm thumbwheel type variable, which is not available in the market. Kindly can you guide me to build this thumbwheel circuit using normal thumbwheel and resistance. Old one was in three units.min 000 and max 999.
    I will be thankfull to you.
    Best Regards
    Shahid Hameed

    ReplyDelete
    Replies
    1. Dear Shahid,

      I have never built a thumbwheel switch, so have little idea about its functioning.......by the way you can opt for a PWM type speed controller which will be more reliable?

      Regards.

      Delete
  18. Hello sir,
    I'm final year ECE student. I'm willing to generate power to my college gym. I have some idea related to that. so I need your some idea relate to that. How can i make power through the weight related exercise machine? we can't use piezo electric crystal. I need some idea.
    and one more thing I'll tell my procedure for that if any mistake arise correct me.
    1.Generate AC power through generator
    2.Gives to the rectifier
    3.Save power in battery
    4.Use inverter for commercial use.

    ReplyDelete
    Replies
    1. Hello Raja,

      That's a very good idea!

      You can use stepper motors or car alternators for generating electricity and for charging batteries.

      I'll try to design the required circuit and publish the article soon, with your name in it.



      Delete
  19. Hello Swagatam,

    Very helpful and informative blog! I came across it some weeks ago while searching for electronics help. I have some experience with electricity, but little with integrated circuits, electronics etc.

    I have a question, which would is proving difficult for me in my electronics ingnorance. I wonder if you would kindly lend some input and suggestions?

    Here is a Link to a rough diagram: https://www.dropbox.com/s/79taqhgccx3p7bn/LED%20logic%20diagram.jpg

    I have four LEDs that running on an 11.1v Li-Ion battery. I wish two of the LEDs to "soft start" or ramp up to full brightness over about 1 to 1.5 seconds. I also would like them to gradually dim OFF over about 1 second.

    The other two LEDs I hope to have strobe at about 10Hz when momentarily triggered. About two 100 millisecond flashes separated by one 100 millisecond OFF should work.
    I was thinking of using an 555IC timer as the momentary input is too brief to flash the LEDs.
    If the input voltage is maintained, I'd like the LEDs to continue to strobe until the input voltage is removed.

    I hope this isn't too confusing, that's why I thought it best to draw a diagram the the circuit logic. Unfortunately my diagram has most of the electronic logic missing as I'm very new. :)

    Please if you have a spare moment reply to me with some helpful pointers or ideas of how to accomplish this.
    Thanks again for hosting such a helpful site!
    Mike

    ReplyDelete
    Replies
    1. Hi Mike,

      Thanks very much!

      You will require the following circuit for the latching actions, eliminate the relay and connect the two LEDs in place of D1 with a series resistor. Since the required ramp is quite quick, it may be accomplished by adding a high value capacitor directly across the LED series, a 1000uF/25V might do the job.

      http://homemadecircuitsandschematics.blogspot.in/2011/12/simple-and-useful-transistor-latch.html

      For the second application you may try a 555 IC, but in an astable mode, because a monostable won't oscillate. the push-on switch may be connected in line with the supply, so when the switch is pushed the operating voltage is applied to the IC for generating the required oscillations to the LEDs at its pin#3..... the 300ms delay can be again obtained by introducing a high value cap right across the IC555 supply terminals. A series resistor must be connected with the LEDs which will also provide the required over current protections to the LEDs.

      Regards.

      Delete
    2. Thank you Swagatam for your speedy, helpful insights and linked diagram.
      I may not have explained the circuit requirements fully for the first application.

      It appears to my novice eyes that once energized, the circuit will remain latched until source voltage is disconnected. Is that right? I may be misunderstanding transistor operation.

      I hope for a circuit that engages with one momentary input. The circuit will latch and keep itself operating. A second momentary input from the same source will disengage the latch. Is that how this circuit works?

      (Referring to your linked diagram), it seems that since voltage is maintained to T1 input through R3, a second momentary InputTrigger at T1 will effect no change? Or does the input voltage difference of R3 vs. InputTrigger cause the transistor to change state?

      I appreciate your patience and kind help in this, and apologize for my lack of understanding, but I'm trying to learn with your great help! :)

      Thanks again
      Mike

      Delete
    3. you are corect Mike, the latch circuit is not a flip flop kind.

      Please refer to the following article, might interest you, however the designs are a bit complex.

      The transistor/relay stage may be removed and the LEDs connected directly with the relevant outputs.

      http://homemadecircuitsandschematics.blogspot.in/2011/12/build-these-simple-flip-flop-circuits.html

      Regards.

      Delete
  20. Sir I need a circuit in which 5 different voltages(0v to 20v discretely) can be generated from a circuit which must be control by IR remote

    ReplyDelete
    Replies
    1. IR sensors are not accurate, they tend to get activated with false triggers, it will require a microcontroller circuit.

      Delete
  21. Swagatam Majumdar,
    Great information on your blog. Can you tell me how to wire a 12 volt circuit that uses an on/off switch to turn on a light bulb that stays on until the switch is turned off but rings a bell or buzzer once or for a few seconds? Thanks for your time,
    Sincerely,
    Mike

    ReplyDelete
    Replies
    1. Thanks Mike!

      I have published the required circuit above, please check it out.

      Delete
  22. Dear Swagatam Majumdar,

    i have a variable speed dc motor 180v 70watt.it has 4 wires. wire no 1&2 resistance is about 50 ohm and wire 3&4 resistance is about 2.2 kilo ohms.kindly can you guide me for a variable speed circuit for this motor.with wire connections?
    i will be thankfull to you.
    Best regards
    Shahid Hameed

    ReplyDelete
    Replies
    1. Dear Shahid,

      I am not sure about the 2.2K wire outputs, but you may connect the 50 Ohm wires in series with a standard dimmer switch unit via a bridge rectifier, a dimmer switch circuit is shown in the following link:

      http://homemadecircuitsandschematics.blogspot.in/2012/04/how-to-make-simplest-triac-flasher.html

      Connect a 1 amp fuse in series with the wiring.

      Delete
    2. Dear Swagatam Majumdar,
      For DC motor speed controller i used 2 bridge rectifier and one Dimmer.i used normal Fan dimmer but i changed its low power triac from BTA41.600B.I checked Dimmer on 200w bulb and it worked good.then i connected one bridge DC output directly with the motor wires (2.2k ohm) and connected other bridge AC input with dimmer and bridge output with motor wires(50 ohm).when i tried to drive motor, its speed didn,t changed according to the dimmer.it drive,s on full speed.
      i checked dimmer and bridge but found ok.
      kindly can you guide me about the problem.i will be thankfull to you.
      AC input is 220v
      motor rating is 200vdc
      bridge output is about 180vdc


      Best Regards
      Shahid Hameed

      Delete
    3. Dear Shahid,

      The bridge rectifier is getting in series with the triac and is providing DC to the dimmer circuit.....triacs and thyristors latch up with DC, therefore the triac is getting latched up, and not doing the dimming functions.
      triac dimmer won't work here.

      you will have to use a PWM controlled circuit, and incorporate a mosfet for controlling the motor speed.

      Delete
    4. Dear Swagatam,
      I connected dimmer in series at the bridge input which is AC 220v,and bridge DC output is connected with motor.

      Best Regards
      Shahid Hameed

      Delete
    5. fine, but the bridge input passage will also convert AC to DC and feed the dimmer triac and will leatch it up....

      Delete
  23. Hi there, fantastic site, very useful information. I have tried searching for a circuit but I am not sure what it's called, I can't find it on your blog. I am looking for a 12v delay start timer. So that when it receives 12v it starts counting for a few seconds (2 or 3) and after finished counting if it still has 12v then it must switch on a 12v relay, is this possible? Thank You.
    Dean.

    ReplyDelete
    Replies
    1. Hi, Thanks!

      You may refer to the diagram given in the following article:

      http://homemadecircuitsandschematics.blogspot.in/2012/12/thermostat-delay-relay-timer-circuit.html

      Eliminate the D2, R6, C3 wiring, and use 12V DC supply in place of 24V AC.
      Also make the relay a 12V type.

      Delete
  24. Dear swagata,
    can you tell me the voltage and amp rating for 5 mm IR leds....and how to light two leds from 1-2 AA batteries...if needed with resistor

    ReplyDelete
    Replies
    1. Dear Avisek,

      it's around 1.4V and 100mA, you will have to use an oscillator circuit for driving these leds....I'll possibly try to present it in my blog sometime in the future.

      Delete
    2. I am making sensor by a led and a transistor...if some obstruction comes in between then it will give signal...why do i need osillator...

      one more question 2 leds connected in parallel can be connected to a AA sized battery or not?

      Delete
    3. IR LEDs are used for trigering a complementary IR photo trasistor, the operations require matching pulsating beams..thereore an oscillator is required.

      probably with individual series resistors conected for each LED, it can be done...

      Delete
  25. Dear Sir Swagatam,

    Almost a year when a friend of mine sold to me his 12v homemade celpone operated security system.
    and found it very useful in my closet door.

    The operation is the unit will call me when somebody had open the closet door and its really works.

    My problem is it takes 3 attempts on the door before the call back features get activated. i know that there is a relay in the circuit handling call button.

    My question is can you give me an addt'l circuit that will automatically flip the relay 3 times so that at the very first attempt on the closet door will instantly activate the call back features and that way i will be informed immediately.

    Sir im hoping that you could help me with this. Thank you in advance.


    Jane

    ReplyDelete
    Replies
    1. Dear Jane,

      it would be difficult to modify your circuit, however you may check my article titled "car GSM security system" where I have discussed a call back circuit which calls the owner instantly when a break in is detected, it might provide you with the required info hopefully.

      Regards.

      Delete
  26. Dear Sir Swagatam

    I built your "PWM controlled DC to DC Cell Phone Charger Circuit". using a multimeter the output reads 11.83v instead of the required 5v. Does D3 and tip122 connected the right way Sir?

    Thanks and more power,

    Jane

    ReplyDelete
    Replies
    1. Dear Jane,

      I think the IC may be faulty, replace it with a new one and check....

      Delete
    2. Dear Jane,

      I am sorry, i thought you are referring to the 7805 charger circuit, ........for the PWM circuit you will have to adjust the pots until you get around 5V at the output

      Delete
  27. Hi Sir,

    Same thing happen after several times i've replace the ic.. BTW Sir i am using a 50k pot in place of 47k for P1, P2 is that matter Sir?

    ReplyDelete
    Replies
    1. I have corrected my answer in the above comment. please read it.

      Delete
  28. Great site!

    I was wondering how simple it would be do to have some LED lights that take 5 seconds to fade on when a switch is turned on and takes 5 seconds when the switch is turned off? What all would I need?

    ReplyDelete
    Replies
    1. Thanks Mike,

      I think I have published one such fader circuit in brighthub.com, possibly I would try to repeat it here as well...

      Delete
    2. That would be great if you could! A lot of nice designs here that I see

      Delete
    3. thanks very much Mike, will try to do it soon.

      Delete
  29. Hello Swagatam,
    I am trying to design a PWM Buck Converter and get a specific Voltage at the output. I am not able to achieve this and have no clue what is wrong. I am new to designing circuits and just trying myself out. I would like to upload the circuit diagram here so that I get some guidance. I don't any option to upload the picture. Please help.

    Thanks & Regards,
    Sharath

    ReplyDelete
    Replies
    1. Hello Sharath,

      you may upload it at wwww.imageshack.us, and give me the upload link here.

      Delete
    2. Hello Swagatam,
      I have uploaded the circuit diagram in this link: http://imageshack.us/photo/my-images/22/pwmbuckconverter7.jpg/

      I have few basic queries while I am trying to simulate this circuit.
      1.Grounding I have provided to Resistor R2. Is that correct. When practically implementing where will this connection of R2 go to.
      2. For triangular signal generation i have used 0V for positive connection of OP-amp. A smaller voltage is also able to give me the triangular wave, but in practice what should be the voltage i need feed here.
      3. Finally what are the parameters i need to play with to be able to arrive at desired voltages at the o/p. Note i am getting 6.7V just before the resistor R7.

      OP-Amp Range settings are as below:
      OP1 & OP2 : 0-15V
      OP3&OP4 : -5 to +5V

      Increasing the voltage on higher side of the range for OP1 is giving me higher voltage at o/p, as the base current flow to the transistor increases resulting in higher o/p Voltage. But i think that's not the right way. I need guidance to achieve this the right way. Also the hFE of the transistor is set to 2000.

      There may be some basic mistakes as well in the circuit as I am pretty new in this. Any additional suggestions would be really be great as well.

      Looking forward for your valuable inputs.

      Thanks & Regards,
      Sharath

      Delete
    3. Hello Sharath,

      I am sorry, I am finding it difficult to simulate the opamp operations in my mind, also the diagram is not clearly drawn so its making things more difficult.

      I think it can be very simply achieved using a 555 circuit......



      Delete
    4. Please find the second circuit which is with 555 timer.

      Buck-Converter with 555 Code:

      $ 3 4.9999999999999996E-6 2.3728258192205156 39 5.0 43
      w 376 192 440 192 0
      w 352 80 376 80 0
      w 128 192 224 192 0
      w 128 96 128 192 0
      w 296 80 320 80 0
      d 128 96 176 32 1 0.805904783
      d 176 144 224 80 1 0.805904783
      d 128 96 176 144 1 0.805904783
      d 176 32 224 80 1 0.805904783
      w 80 144 176 144 0
      w 80 32 176 32 0
      v 80 32 80 144 0 1 100.0 28.0 25.0 0.0 0.5
      l 376 80 440 80 0 0.125 9.612174503520412
      w 440 192 520 192 0
      r 520 80 520 192 0 3.5
      c 440 80 440 192 0 0.02 34.40671683004071
      w 440 80 480 80 0
      d 376 192 376 80 1 0.805904783
      t 336 128 336 80 1 1 -20.690329507896223 0.8049159170347155 100.0
      r 336 128 336 176 0 5.0
      w 224 80 264 80 0
      c 224 80 224 192 0 0.05 50.10423448404686
      w 264 80 296 80 0
      w 264 192 376 192 0
      w 224 192 264 192 0
      165 280 296 312 296 3 5.0
      R 312 280 312 248 0 0 40.0 5.0 0.0 0.0 0.5
      w 344 328 376 328 0
      w 312 280 256 280 0
      r 256 280 256 312 0 500.0
      r 256 312 256 344 0 10000.0
      w 256 344 256 360 0
      w 256 360 280 360 0
      w 256 344 280 344 0
      w 256 312 280 312 0
      c 256 360 256 392 0 3.0E-6 2.2731808535333484
      w 80 144 80 392 0
      w 80 392 256 392 0
      w 480 80 520 80 0
      w 480 80 480 392 0
      w 312 376 312 400 0
      w 456 392 480 392 0
      R 552 320 552 344 0 3 20.0 2.0 3.0 0.0 0.5
      g 256 392 256 424 0
      w 312 280 344 280 0
      w 344 280 344 312 0
      w 336 176 336 256 0
      w 336 256 376 256 0
      w 376 256 376 328 0
      a 416 400 360 400 3 15.0 -15.0 1000000.0
      w 312 400 360 400 0
      w 416 408 416 432 0
      w 360 400 360 432 0
      r 360 432 416 432 0 10.0
      r 416 392 456 392 0 100.0
      r 416 392 416 336 0 100.0
      g 416 336 416 312 0
      r 416 432 480 432 0 100.0
      R 552 392 592 392 0 0 40.0 5.0 0.0 0.0 0.5
      w 480 392 480 432 0
      o 14 64 0 35 40.0 12.8 0 -1
      o 27 64 0 35 5.0 0.4 1 -1
      o 50 64 0 34 20.0 0.003125 2 -1
      o 39 64 0 34 40.0 0.1 3 -1

      Delete
    5. Hi Sharath,

      I don't rely on simulators, I'll advise you to make the circuit and check the results through practical assessment.

      Buck boost designs are quite straightforward, and would always work if done correctly.

      Delete
  30. Hello Swagatam,
    Thank you. can you give me reference of any buck boost design. I will try it out.

    Regards,
    sharath

    ReplyDelete
    Replies
    1. Hello Sharath,

      You can try this circuit:

      http://homemadecircuitsandschematics.blogspot.in/2012/05/making-adjustable-electromagnet-circuit.html

      Just replace EM with a coil wound over a ferrite rod, it can be a 22swg magnetic wire 100 turns wound over a radio MW antenna coil ferrite rod.

      Delete
    2. Hello Swagatam,
      Thank you. I will check this and will come back if I get stuck.

      Regards,
      Sharath

      Delete
  31. Excellent site!
    I am after a circuit design similar to the LED Bar Graph circuit that is found on this site/blog.

    What I want to develop is a front turn signal sequential flasher that illuminates and holds the lights from top to bottom and then cycles them again and again until the turn signal is turned off.

    I need to drive exactly 12 Amber LED's that drop 1.8 volts per LED. The LED's are laid out from top to bottom as such.
    1 (number of LED's)
    1(number of LED's)
    1(number of LED's)
    2(number of LED's)
    3(number of LED's)
    4(number of LED's)

    I would like to illuminate the first one at the top and hold and then move on to the second one down and so forth until all 6 rows which consist of 12 total LED's are illuminated and then start the sequence over. Variable resistors should be included so that the clock frequency can be altered. This will allow me speed up or slow down the illumination and hold of the LED's. Plus if there is a variance in the driver side circuit and the passenger side I could use the adjustability to "syncronize" the working rates of both sides. (turning on the hazard flashers to observe both sides being enabled and sequencing would be a good way to visually check this)
    In the connector to the front turn signals I am working with three connections. Top pin is 12 volts constant when running lights are turned on (oh, just a thought- It would be nice to use the entire string of LED's as running lights as well) Middle Pin is zero volts (GROUND) and lower pin is 0-12 volts when the turn signal is activated.

    I need a working circuit that will handle automotive voltages that are not always 12 volts in practice , but can range up to 14 or so volts in actual real world use.

    A complete circuit diagram would be helpful. Including resistor values for driving the different multiples of LED's and if each LED would have its own resistor or just run them in series with one resistor.
    b d zero g @ comcast.net

    Thank you.

    ReplyDelete
    Replies
    1. Thanks very much!

      I have noted down the request, however due to many previous pending requests it might take some time to get it published.

      kindly bear with us...

      Regards.

      Delete
  32. I eagerly await the circuit design as my front turn signals will not be completed until I get this circuit together.
    To expedite the process perhaps I can gather parts in anticipation of the circuit completion. Could you provide a basic parts list? Resistors , Transistors, Caps, Model of SCR and Model of IC's? I will get all those items together along with some proto board and be "Locked and Loaded"

    Thanks for your help Swagatam!

    If I can provide more specifics please feel free to email me at

    b d zero g @ comcas.net

    ReplyDelete
    Replies
    1. Please give me a couple of days more, though there are a quite a few previous requests to be completed, I'll try to finish yours first as you seem to be more eager with the project :)

      In the meantime Unntil it the article published you may procure the foollowing sets of parts:

      Resistors all 1/4 watt cfr

      680 ohms 6nos

      33k

      4.7uF/25V capacitor 1no

      IC 555 1no

      IC 4017 1no

      IC 7812 1no

      SCR BT139 6no

      Transistor BC557 1 no

      general type PCB

      There might be some additional tings which I would tell you after completing the design. The design will be pretty much similar to the bar graph design which you have already read.


      Delete
  33. I think that I will need to double the parts quantity as I need to develop one circuit for the right turn signal in the front and one for the left unless I am mistaken? I can start by constructing the basic circuit for the bar graph I guess? Suggestions for a good protoboard type to use? Online link or reference?


    Thanks for the help! Im looking forward to having this super cool way of signaling in my vehicle. I probably need some of those super bright 5 mm LED's from superbrightleds.com I guess?

    ReplyDelete
    Replies
    1. Yes two channels would be required, one for each side on the vehicle.

      Any general purpose board can be used for assembling the parts, one example can be seen in the following link:

      http://2.bp.blogspot.com/-EtNM2PIX338/T5jq2cy3duI/AAAAAAAABKk/F1_ijnauMG4/s1600/parts%20for%20the%20circuit.jpg

      I am working on the design, you would it see it soon

      Delete
  34. Thanks very much for your assistance! I have the parts on order and have doubled the quantities that you listed in the above post , I am even considering trying my hand at custom etching a pcb for the design but would need a way to convert the circuit using an easy to understand pcb layout tool. I have always wanted to challenge myself and layout, etch, and drill a custom pcb .

    First step would be proof of circuit operation using a orotoboard and manually connecting using wires . Then once it works as planned with reliability I would venture into etching the pcb. Suggestions on pcb layout software that I could drop the design into would be great so I could start learning to use it.

    This really gets me motivated to build circuits again! Dusting off my old soldering iron and all related tools gives me a sense of renewed enthusiasm!

    ReplyDelete
    Replies
    1. I usually do PCB designing in coreldraw and for me it works best....I have never used any specific softwares so don't know much about them....however you can probably find many free online PCB designing softwares on the net...

      Regards.

      Delete
  35. Going to use CadSoft EAGLE as the learning curve does not sound too steep and it has a lot of built in libraries that contain a good deal of parts that can just be selected and placed. It has a freeware version that should suit my needs as it only restricts multi layer board design and the size of the overall board developed. I wont need multi layer just solder side (bottom) and component side (top) Wont need to use the Via's either as all connections will be on the bottom side with the traces.

    ReplyDelete
  36. hi sir swagatam
    my question is that why we use relay in stablizer????

    ReplyDelete
    Replies
    1. hi waseem, it's for switching heavy AC loads through DC control circuits.

      Delete
  37. Hi Sawagatam

    I need to monitor the voltage change of a square wave signal. In normal operation, the signal fluctuates between 12 and 10.5V. In testing mode, the signal fluctuates between 12 and 11V. This means the lower limit of the signal voltage has increased by 0.5v. How can I use an Op Amp to monitor this increase? Thanks in advance for your advice.

    ReplyDelete
    Replies
    1. Hi Abu Hafss,
      You can use the IC741, the reference or the threshold voltage level which needs to be monitored should be fixed to pin#2, and the fluctuating voltage applied to pin#3, so pin#3 will monitor any rise in voltage with reference to pin#2 voltage. suppose if voltage at pin#2 is fixed at 10.5V, then if pin#3 voltage rises by even 0.1V, the output will become high...but the amount of increase cannot be read.

      Delete
  38. Hi Swagatam

    With respect to my earlier post, here is a schematic on which I am working. Would you please check it and let me know if my approach is correct. Otherwise, please suggest modifications. Thanks.

    https://dl.dropboxusercontent.com/u/20969135/Sq%20Wave%20Comparision.gif

    ReplyDelete
    Replies
    1. Hi Abu-Hafss,

      that looks like a window comparator, looks good, it should provide you with the required indications, but I couldn't understand the output of LM339 connections..

      Delete
  39. Hi Swagatam

    Can you please design me a Sq wave oscillator using an Op Amp having a frequency of 2.8Hz and duty cycle 45-60%. I tried following examples on the net but could not control the parameters. Also I noticed the oscillation does not start immediately.

    ReplyDelete
    Replies
    1. Hi Abu-Hafss,

      You can check out the following circuit:

      http://www.onegentleman.biz/Hardware%20Design/Op-Amp%20Oscillators/Osc%20Pics/fig-14.jpg

      Delete
  40. Hello Sir,
    I am a second year Undergrad Student, from the ECE branch. However our technical study has been lacking and we are mostly encouraged to " LEARN" existing circuits.
    I am interested in Circuit designing , however my technical education does not allow me to pursue this.
    Any word of advice would be welcome as to where i should start and how to go about it.
    Thank you sir,
    [Name Withheld]

    ReplyDelete
    Replies
    1. It can be a very long journey....you will have to first get well versed with the basics and gradually go for the practicals and other more complex designs. there are many online tutorial sites full of basic stuffs, you may refer to them initially, if in problem you may feel free to ask them here.

      Delete
  41. Hi Swagatam,

    I a have a Dlink ADSL modem which is powered by a 12V 1A adaptor. In my area Electricity goes very often. I thought of making a inverter or a UPS for about 50W; I came across your site, this is a very informative

    I wanted to know can I connect my modem directly with a 12V battery and charge my battery with a charger

    If yes then What is the size of battery I need and which circuit I can use to rechrage my battery

    Thanks in advance
    Amit

    ReplyDelete
    Replies
    1. Hi Amit,

      If you are able to operate your modem with a 12V/1amp adaptor it means it can be operated with a small 12V battery also. You can connect a 12V battery with the modem directly. You may use 12V 7.5AH battery for this.

      For charging the battery you may procure a 14V/1amp DC adapter and charge the battery for approximately 7 to 10 hours.

      Delete
  42. Thanks Swagatam

    I will try,
    One silly question : By connecting 14V / 1amp adapter to rechargeable battery, it will recharge ?

    thanks
    Amitjain

    ReplyDelete
  43. sir,
    m a beginner need to make a variable power supply (5-30V) plz give me a circuit to make the same nd plz mention the ranges of each components , i wud like to make it simple one so plz kindly help
    priyanka

    ReplyDelete
    Replies
    1. Hi Priyanka,

      You can use an LM317 IC for making a simple variable power supply, please refer to the following article:

      http://homemadecircuitsandschematics.blogspot.in/2011/12/how-to-build-simplest-variable-power.html

      Delete
  44. Sir,
    I want to design Grid-Tie Inverter of 60-70watt. So plz you send me circuit diagram of grid-tie inverter , component list of that. Plz sir help me.
    Mohini

    ReplyDelete
    Replies
    1. You can refer to the following discussion and try one for yourself:

      http://homemadecircuitsandschematics.blogspot.in/2012/10/designing-grid-tie-inverter-circuit.html

      Delete
  45. Sir,
    I need to design a Compact flourescent Lamp (CFL)in MATLAB/simulink software
    I need CFL equivalent circuit with parameters, component values.
    So could you please provide me the circuit of it.

    Thank you

    ReplyDelete
  46. Outstanding info here! Trying to soak it all up.
    I would like to build a circuit that actually incorporates 2 that you have posted here, also utilizing some extras you have mentioned before. I want to control two 7 segment LED lights(2-3 led's in each segment) with an IC 4017 and an IC 4060 so they flash sequentially, but I want each segment to stay on until all segments are lit and then go off and repeat the process as long as the turn signal switch is on. I also want the segments all to light at one time when the brake is applied, but I need the sequential to override the brake so If I have the brake applied and the turn signal on, the brake will light up on one taillight and the blinker will light up on the other depending on which turn signal is on (ie left or right). I don't think I need to control the brightness but I will need to be able to adjust the sequence rate. You have a couple diagrams posted that can do this but I'm not sure how to incorporate them together. If you can help, I would be very grateful.

    ReplyDelete
    Replies
    1. You can refer to this circuit, it's exactly as per your requirement:

      http://homemadecircuitsandschematics.blogspot.in/2013/03/sequential-bar-graph-turn-light.html

      The override feature can be included simply by adding a relay stage, I'll explain it to you later on once you grasp the proposed design.

      Delete
  47. Thank you for the reply. That's actually one of the circuits I was looking at and I understand it pretty well. The other circuit had the brake light incorporated also, which I need, but there was a modification needed to the circuit so the brake light would not override the sequential turn signal, and it didn't have the bt169's for the latching mechanism. I'll build this one first and we can go from there. I have never posted on a blog before. Is this the correct place to post, seeking your advice as I continue with the project? I'm afraid it will be difficult to know where we are.
    Many Thanks, Chris

    ReplyDelete
    Replies
    1. Great!
      We can carry on the conversation under the referred article itself, it would help the other readers to follow them as well.

      Regards.

      Delete
  48. Thanks. I will make a post over there.
    Chris

    ReplyDelete
  49. Hello.

    I am kind of stumped on a project I'm working on and looking for help. I am trying to build an IR Stop Motion Relay Switch. Basically, it uses the optical wheel from an old mouse and the IR emitter/detector for the motion sensor. Once the wheel spins and the sensor detects motion, it will trip the system high and fluctuate one side of a duel-color LED with the brightness relative to the rotational speed of the optical wheel. Once the systems senses no-motion, the system will be low and trigger a 3-second time-delayed relay that will switch the LED color to its alternate and remain in a solid ON state until reset via PB switch. I have the motion circuit and the relay circuit. But I'm having trouble with the Motion-to-LED fluctuation interpreter. This is for a fishing application so the package must be small.

    Any help with this would be greatly appreciated

    Thank you.

    ReplyDelete
    Replies
    1. Hello,

      You can try the first circuit shown in this article:

      http://homemadecircuitsandschematics.blogspot.in/2012/03/how-to-make-vibration-detectormeter.html

      Remove the piezo element and apply the sensor output across pin#5 and ground of the IC.

      Use any one of the outputs out of the 10 for driving the blinking side of the LEd.

      Delete
    2. Thank you very much for the quick response. Just so I'm clear: pin 1, for example, could be tied to the LED and pin 15 (5th LED in) could trip the relay. Then the Pizo would be replaced with the motion detection sensor. This is close to what I am looking for but it's more of a bright-to-dim lighting based on the speed in which the motion of the Ferris wheel passes through the detector. Faster the spin, brighter the bulb; slower the turn, dimmer the light. Once motion stops, the light switches to always on until reset. Kind of like attaching a light to an audio amplifier where the volume would pulsate the bulb according to the beat of the music. But replacing sound with motion and then switch when motion stops. Any ideas?

      Delete
    3. Design change...

      High _ Flash ___
      ---------|_|-------|___|----|
      _ | LED1-A | _
      >------|_|------| | <- Relay ---|_|-->
      Vcc Motion | _ ON ___ | Reset
      ---------|_|-------|___|----|
      LED1-B
      Low

      Motion: Ferris Wheel IR Emitter/Detector w/Encoder

      Relay: - Motion triggers relay HIGH for single LED flash sequence
      - Stop motion triggers relay to LOW for same LED to always on until reset

      Flash: Speed of flashing sequence relative to input signal of IR Encoder

      Solid: Dual-color LED switches to secondary color for always on state

      Reset: Once relay set low and light is on, reset will turn light off until motion detected again.

      (Hope this formatting comes out right and makes sense.)

      Delete
    4. The circuit which I have suggested will blink the selected LED in response to motion sensor output, because the motion sensor will produce pulsating DC to the input of the IC, which will cause the selected to LED to switch ON/OFF to produce a flickering effect.

      Any central LED can be selected.

      I could not understand the formatting which you have shown, can you explain it text form?

      Delete
    5. ya, ANSI formatting didn't go too well I see. Sorry about that.

      Basically, Once the detector senses motion, it trips a relay high and starts the flash pattern. Once the motion signal stops, the relay trips again to low and stops the flash and turn the light on solid until rest via a reset switch.

      Delete
    6. Figured it out... I think. Its on paper right now. Let me make a cad of it and I will post you what I have.

      Delete
    7. OK it means your motion detector produces logic high and low outputs for the motions, is it? In that case the blinking LED circuit becomes too simply, just use a IC555 astable circuit and connect its supply pins to the relay such that it gets the required supply through the relevant relay contacts, and connect the LED pin across the 555 output.

      Delete
  50. I have a cad drawing for you but not sure how to paste it. I transferred it to a .jpg so I can post it as a pic. Any ideas?

    And again... Thank you so much for your help!

    ReplyDelete
  51. HI Swagatam,
    I need a circuit diagram of my DMM (Kipco DT830D).Few smd resistors were blown accedently.Or i just need values of that blown resistors only.
    I also want to repalce its 9v batery to external wall plug adapter for power purpuse.
    How can i khow exact power rating of my DMM while i fed it by any wall adapter.
    pls help me regarding these issues.
    Naeem,
    Thnkx.

    ReplyDelete
    Replies
    1. Hi Naeem,

      The circuit design of DMMs are always specific as per the company specs, it's never a common standard design so it can be difficult to trace the layout and the faults, I don't have much idea about it.

      Delete
    2. Hello Naeem,

      If I may offer a thought...

      If you can get inside the DMM and physically look at the components and identify the bad resistors, then look for the color bands. If they're not burnt, and you can still see them, then you can calculate the values. The first 2 bands will be the values. (B B R O Y G B V G W) The 3rd is the multiplier. (exp. Red -> Red -> Brown = 2 -> 2 x 100 = 220ohms. Google "Resistor color code" for more info.

      as for the power, what kind of batteries does it take? 9vDC? Then most (not all) off-the-shelf 9v's are 500mAh. Therefore, you would need a supply what is rated for an output of 9vDC @ 500mAh. You can go a little lower like a 450mAh but do not go over. Over power will fry other components.

      Hope this helps.

      Delete
  52. Sent you an email with a better description of what I am working on. Thanks again for all your help.

    ReplyDelete
    Replies
    1. I'll take a look at it as soon as I am free.

      Delete
  53. Thnkx Tyendaga for help.
    Actually my DMM has smd type resistors.3 out of these smd resistors have burnt n unfortunatley i m unable to see exact marking of these 3 resistors therefore my diode test range and 200ohm range r not displaying correct results.Thts y im looking 4 my DMM schematica.
    Secondly ths DMM has PP3 type 9v battery.I want to khow about this battery power rating.

    Also how can i take 3v from 9v input coz i has another analog meter.It has 9v & 2*1.5v batteries in it.SimilarIy i want to power this meter with my adaptor.So how can i power this analog meter safely by ac adaptor.Guide me pls.
    Thnkx
    Naeem.

    ReplyDelete
  54. Hello, I am looking for a simple timer circuit to control the 115v feed motor on a pellet stove.The timer needs to be adjustable from 0 to 10 seconds delay (off period) with 1 to 2 seconds of run time (on period).

    ReplyDelete
    Replies
    1. you can try the following design:

      http://homemadecircuitsandschematics.blogspot.in/2012/04/how-to-make-simple-programmable-timer.html

      Delete
  55. hi Swagatam i'm a regular reader of your blog, it was good, keep it up. i've a 5.1 assembled amplifier and it has separate controls for front speaker, centre speaker, surround speaker & sub-woofer but it doesn't have master volume control but now i like to additionally add one master volume control for the same but i don't know whatever i've to bought and how to install it my amplifier, so can you please guide me??

    and my amplifier was made by 24-0-24-0-24-0 7amps transformer, please help me thank you.

    ReplyDelete
    Replies
    1. Hi MDF,

      You can do it by adding a 10K pot in betwee the music source and the amp input. The amp hot end should be connected to the center pin of the pot, one of the outer ends may be connected to ground or the common rail of music source and amp input, and finally the music input connects with the other outer pin of the pot.

      Delete
  56. Hi Swagatam.
    Just stumbled accross your site, hope you can help/advise me?

    I have a 1999 Mercedes SLK and it has a well-known design flaw, the doors are frameless and the windows have the closed position set mechanically by a small metal bracket glued to the window within the door which stops the window at the correct position when closed so when the doors are opened and closed the window just catches the rubber seal as the door closes and allows the window to slide into the recess.
    The problem is these brackets fall off allowing the window to close a couple of mm higher than designed which isn’t a problem for the window mech but this causes the window to catch on the rubber door seal and not sit into the seal recess properly, the only way to close the door properly is to drop the window slightly before closing the door.

    The door seals on my car are being worn out by the window rubbing on them when the door is closed and the on closing the window is being held on the outside of the door seal so I had an idea to incorporate a timer circuit to drop window few mm on opening the door then close it again after the door is shut, ideally to be activated by the ground signal for the interior lamp (i'm assuming its a ground sig but havent checked yet)

    BMW 3 series (and poss others) have for many years had such a system incorporated in the car at manufacture that drops the window a couple of mm when the door is opened and closes the window when the door is closed and I think this car should have had this system when designed!


    My idea is to use a 555 timer circuit to achieve this but the last time I dabbled in circuit design was over 20 years ago and it is giving me a big headache trying to remember the theory, any help or advice would be much appreciated and although most modern cars have now taken BMW’s initiative and now include this function there may even be a market out there for such a seal saving device on older cars?

    Description of operation of the circuit

    1) Door opens, ground signal applied from door switch
    2) Momentary energises relay or output to apply +12V 20A for approx 500 milliseconds (this time may need to be adjusted when fitted) to momentary send the window down (open) a fraction (this output to be connected to the window open button of the car)
    3) On closing the door, ground signal removed
    4) Momentary energises relay or output to apply +12V 20A for approx 1 second (this time may need to be adjusted when fitted) to momentary send the window up (closed) (this output to be connected to the window close button of the car)

    Any advice much appreciated!

    Mark

    ReplyDelete
    Replies
    1. Hi Mark,

      I got it, thanks! Actually this would require a simple transistor driven relay circuit with a capacitor for the required delay. However are the time difference between the ON and OFF of the relay crucial? I mean if we make both the timing = 500msec or 1 sec will it make any difference?
      If it's not then I think it could be a very simple design.
      Please clarify the above issue, I'll design it for you.

      Delete
    2. hi Swagatam.
      Thanks for replying, the time for the relay activation isn't that crucial, it would just open the window more the longer the relay stayed energised, I just thought to best keep the relay energised longer at door close to ensure the window fully closes.

      Thanks
      Mark

      Delete
    3. Hi Mark,

      Please see the last circuit presented in the above page, I think this will do the job, however the timing would be equal for both the switching. It can altered a bit(equally) by tweaking the values of the two 1000uF capacitors connected in series with relay contacts. The polarity of the caps are critical and should be connected as given in the diagram.

      Delete
    4. Thants Great!! Many Thanks Swagatam!
      I think i may have been overcomplicating the circuit by using a 555 timer.

      If I understand correctly the outputs marked solenoid would connect to the coils of 2 relays (one to send the open signal and one to send the close)? if this is the case do you think by adding a 1000uf cap across the close contacts would make the close relay energise for longer than the open relay to ensure the window is fully closed?
      I have drafted a jpg image showing the additional components and would like to know your thoughts if i can send it to you somehow?

      Many Thanks!
      Mark

      Delete
    5. Hi Mark,

      It's my pleasure!

      I thought the window mechanism had a solenoid, so as per the diagram, the solenoid refers to a motor mechanism which controls the window up/down....this is what I assumed. If it's something different to this then I think I will require a more accurate information regarding the mechanism or the relay as you have mentioned.

      You can send to my email ID hitman2008@live.in if you have any additional info I'll try to assess and rectify the circuit accordingly.

      Delete
  57. Sir,

    Can you please design a circuit that generates ultrasonic sound with frequency range b/w 18KHz to 33KHz. I want to use it to control dog barking.

    Regards

    Jagadish Kumar S

    ReplyDelete
    Replies
    1. I'll try to do it soon, but ultrasonic devices are not so effective in driving animals away.

      Delete
    2. what is the alternate you suggest sir?

      Delete
    3. actually there's no easy way of doing it, one method is by spraying water towards the dogs.

      Delete
  58. Sir, Can you please write an article about lm339 compactor uses in inverter including sg3524.
    With Regards

    ReplyDelete
  59. Please provide a CDI circuit without a pulser coil input to CDI

    ReplyDelete
    Replies
    1. A CDI cannot function without a coil, the coil is the heart of the CDI

      Delete
  60. Hi Swagatam sir could you please publish a automatic 5 kva ac relay type voltage stabilizer schematics from input voltage 70-300v ac and output should be 220 volt.

    ReplyDelete
    Replies
    1. Hi Arindam, you can try the following circuit, the number of outputs can be upgraded by adding more number of opamps and relays.

      http://homemadecircuitsandschematics.blogspot.in/2011/12/how-to-make-accurate-7-stage-op-amp.html

      Delete
  61. sir ,

    i am kathiravan . i have sent you a request for swatter bat circuit to your homemadecircuits id sir.reminding you sir . please post a complete
    info and schematic for it sir with both versions step down transformer and also with ac voltage dropping capacitor .

    ReplyDelete
    Replies
    1. Hi Kathiravan,

      I'll try to post it soon for you.

      Delete
  62. hi Swagatam Majumdar
    can you guide me design and calcular a mobin wind capacity small.
    can you send to me in address hongkhang.ly@gmail.com
    thanks so much

    ReplyDelete
    Replies
    1. Hi Khang,
      please provide complete details regarding your requirement, I'll try to help.

      Delete
  63. hi swagatam,
    plz make modification in your blog website.
    the search bar is not available in mobile view of web site.(esp. opera mini)
    therefore it is very difficult process to jump from particular articles

    ReplyDelete
    Replies
    1. Hi Jignesh,

      I'll do it soon, thanks for pointing it out.

      Delete
  64. Hi Swagatam,

    I am looking for circuit comprising of the comparator (LM 324) to drive a relay. The objective of this circuit is to:

    1. Sense AC supply and switch relay 'ON' when voltage is in between 180-250V.
    2. Relay should turned 'ON' after 5 seconds
    3. Relay should turned 'ON' after zero voltage detection of supplied AC (Zero voltage detector). This is to minimize arching in the relay contacts.
    4. Finally and most importantly, the relay switchover time should be less than 5 ms as a normal off-line UPS does.
    5. LED indicator to indicate the state of relay.

    The above functionality can be found in UPS circuit which is bit complex to understanding since UPS has many other functional circuit beside this. So am looking for a separate simpler circuit which only works as mentioned above. Kindly help me to build the circuit.

    Component available and other details:
    AC mains = 220V
    Battery = 12 V
    Comparator = LM 324 or something similar
    Transistor = BC 548 or BC 547
    All type of Zener are available
    All types of resistor are available

    Thanks and Best regards,
    Deepak

    ReplyDelete
    Replies
    1. Hi Deepak,
      I'll try to design and publish it in my blog soon.

      Delete
    2. Hi Swagatam,
      Thank you for your prompt response. Kindly be reminded that relay 'ON' or 'OFF' time is very crucial for the application i am looking at. Meaning that relay switchover time for both modes (ON and OFF) should be less than 5 ms. Basically i am trying to make a circuit that will make two UPS to run in redundant mode to supply power to Load like computers, routers etc. That is to say two UPS output goes to circuit, the circuit keeps checking the availability of power from first UPS and supply power to load from first UPS. In case if the first UPS experiences any problem and dies out then the circuit will quickly switch to second UPS and continues supplying power without interruption to the load like computer, router. I would be grateful if you could suggest better circuits or ideas (than the one i am thinking) to meet above requirement. Thanking you.

      Best Regards,
      Deepak

      Delete
    3. Hi Deepak,

      The relay switching time will depend on the relay mechanism specs, and the supply parameters, it'll need to be optimized correctly by selecting the right relays.
      I'll see if I can get all things in the right order.

      Regards.

      Delete
  65. Hi.
    I need help to repair My speaker. Can u help me?

    ReplyDelete
  66. hello sir
    just i wana to make a circuit wich work in such a way that when ac supply is off then dc supply automatically on but when ac supply is on then dc supply automatically off.pls post a circuit with proper explanation. ..

    ReplyDelete
    Replies
    1. hello trilok, i have already answered your question in the other comment.

      Delete
  67. Hi Swagatam,

    Thank you for UPS relay circuit. I am trying to build it very soon. I will update you the result once i am done with that.

    Next, i am very keen to build a Solar charge controller circuit for following requirement.

    1. Battery shall be of 48 V (lead acid or maintenance free) with capacity go up to 48V X 600 AH.
    2. Load to battery may be up to 1500 W (30 Amp at 48V)
    3. Solar PV cell in series/parallel configuration producing voltage up to 60V and 40 Amps

    The controller circuit is expected to perform as follows.

    1. Cut off solar supply to battery when its voltage reaches approx 56V and maintain appropriate hysteresis to avoid frequent switching of power MOSFET. So the solar supply to battery would resume again only when the battery voltage reaches approx 48 V.

    2. Low voltage disconnect of load from batter supply when battery reaches around 45 V and maintain appropriate hysteresis to avoid frequent power ON/OFF of load.

    I will be grateful if you could help me building this circuit.

    Thanking you.

    Best regards,
    Deepak

    ReplyDelete
    Replies
    1. Hi Deepak,

      I'll try publish it soon in my blog.

      Delete
  68. hello sir,
    I want to use LM35 temperature sensor to read the surface temperature.
    The output of LM35 is 10mV per degree celsius. I want to convert the analog output corresponding to the temperature to digital values.

    After that I want to send those digital values to a receiver Using RF communication.

    How do I achieve this? Can you suggest ?

    ReplyDelete
    Replies
    1. hello akshay,

      sending the info through RF will require a sophisticated circuit, presently I do not have it, i'll try to find and let you know.

      Delete
  69. Dear Swagatam

    Please could you assist me with a circuit design for a special 12 volt battery charger
    My challenge is that I have 6 Black and Decker 12v battery operated off the shelf battery operated tools
    sometimes when I charge them I forget to unplug them when fully charged or
    if I do not use them for a long while they go below minimum level
    Both way I end up damaging my batteries.

    Please could you help in designing a charger that will switch off at ±13.5v and switch on at ±10.5v
    It could be one unit supplying all six drills or preferably one unit per drill

    Many thanks
    Ally

    ReplyDelete
    Replies
    1. Dear Ally,

      Please refer to the following diagram:

      http://2.bp.blogspot.com/-hyaeF1VohqU/Uc0V0eR8tbI/AAAAAAAAErw/SGgmiaoWIxQ/s601/automatic+battery+charger+circuit.png

      Please ignore and remove the right hand side relay and its connections, they are not relevant to the design

      Delete
  70. hello sir.
    Sir i am a student of electronics. i need your kind help in designing charge controller for 24 volts. Two solar panels are connected in parallel each having 5 amp rating( total 10 amp). sir, i need simple circuit diagram which stop the charging when the battery got full. Also having knob for adjusting cutoff voltage. I will be very thankful.

    sincerely yours.
    FAZLI AMIN KHALIL

    ReplyDelete
    Replies
    1. Hello Fazli,

      you can make the second circuit shown in the following link:

      http://homemadecircuitsandschematics.blogspot.in/2011/12/how-to-make-simple-low-battery-voltage.html

      Delete
    2. thank you sir,
      if any problem , i will contact you..

      Delete
  71. Swagatam Majumdar hello sir my name is ariel from Argentina. I need your help, I have a lcd tv and I can not find the source integrated tv and this is OB6572AP shorted. you can tell me an easy replacement obtained by a commercial integrated. please thank you very much for your help.
    ARIEL from Argentina

    ReplyDelete
    Replies
    1. Sorry Amir, I searched a lot for its equivalent but couldn't find any on the net

      Delete
  72. Hi swagatam I'm new to electronics I was planning to build a melody circuit for door bell purpose , I came across several circuits I've chosen um3481 series circuits to start with, when I enquirer for um 3481 ic the shopkeeper gave me wr630161 which also has 16 pin , when I tried making the circuit as per um3481 data sheet it's not working . I would like to clarify the mentioned ic is equivalent model or it's different one. If possible can u send me a schematic using this ic for me , it would be much helpful for a starter like me. I tried searching the same over tthe net I couldn't find some. Please help
    haf2eez@hotmail.com

    ReplyDelete
    Replies
    1. Hi Hafeez, I too tried to search the datasheet of the IC but could not find any, since I do not want to trust the other unreliable sources I wouldn't be able to suggest you regarding it.
      You can try using UM66 IC it's hugely simple, cheap and easier to configure.
      You can easily make a doorbell from it. but it won't produce multiple tones rather a single tone only.

      UM3481 is also pretty popular I think you should look for it in other shops or get it online

      Delete
  73. Swagatam I need ur help in indentifying an ic wr630161 , if possible can u get me a circuit for door bell

    ReplyDelete
  74. Thanks for ur response mate. I couldn't find a circuit for um66 which can play thr music continously and stop once thr melody gets over via single trigger through AC 230 v. With a built In amp for more volume , if u can help me out with this circuit will be much appreciated.

    ReplyDelete
    Replies
    1. Hafeez, you can refer to the following article:

      http://www.edutek.ltd.uk/Binaries/Datasheets/Linear/UM66.PDF

      It shows the UM66 one-shot designs but using 3V batt pack, you can easily replace the 3V batt with a cell phone charger supply (with a 100 ohms series resistor) for the same.

      I think an amplifier won't be needed as the circuit itself is able to produce quite a loud music, however if at all it's needed you may incorporate a LM386 IC stage for greater amplifications.

      Delete
    2. Thank you very much swagatam for ur prompt response . Many thanks for ur help,

      Delete
  75. Hi Swagatam,

    I am looking for DC - DC buck converter with following features.

    1. Input voltage = 40 to 60 VDC
    2. Output voltage = Regulated 12, 18 and 24 VDC (multiple output from the same circuit is not required. Separate circuit for each o/p voltage is also fine)
    3. Output current capacity = 5-10A
    4. Protection at output = Over current, short circuits etc.
    5. Small LED indicator for unit operation would be an advantage.

    Appreciate if you could help me designing the circuit.

    Best regards,
    Deepak

    ReplyDelete
  76. what a genius you are, i salute your courage in sharing known knowledge with the populace....i pray God increase you in knowledge and as well pray God in his mercy endowed me with such knowledge.
    sir, i am new to electronics and i love to design, i tried the inverter circuit you shared using Proteus simulation software but i didn't get i t(it keep giving me -11.v at the input of the transformer and 0v at the output of the transformer), though i have problem in manipulating the transformer in Proteus.
    so, I'd appreciate if you can help me with another design software and as well guide me in step to manipulating the transformer in proteus.
    thanks and God bless you sir

    ReplyDelete
    Replies
    1. Thank you Azeez, which circuit did you try? I have plenty of inverter circuits in this blog so can't remember which one I suggested you.

      Simulators are never accurate and many a times give wrong or confusing results, I would advise that you try the circuit practically, I can suggest the reliable ones that would certainly work.

      Delete
  77. thanks for your reply. am talking about this http://homemadecircuitsandschematics.blogspot.in/2012/02/how-to-make-simplest-inverter-circuit.html?m=1) i did everything correctly, but there is no transformer with center tapped primary on proteus 6. that am using, moreso i have problem editing the transformer to get 12-0-12 and 5amp. thanks

    ReplyDelete
    Replies
    1. This circuit has been tested by me thoroughly and will work for sure. I have no idea about simulators so won't be able to provide a valid info.

      for practical testing use 9-0-9V/5amp transformer and a 12V 10ah battery for optimum results, a correct 5amp trafo would weigh around 4kgs, otherwise it may not be a 5amp.

      Delete
  78. sir, i need you to as well suggest the reliable ones as stated in your reply. thanks

    ReplyDelete
    Replies
    1. All designs presented in this blog are reliable, the spec selection will depend on the application needs and user capability.

      Delete
  79. I am looking for a guide to build a basic temp regulator circuit. I have a solar charger bought from lidl,(SLS 2200 A1) which has outputs for 5, 7.5 & 9.5v DC 0.5A. it will be used for soil heating in a greenhouse. My idea is to use black drip irrigation pipe as a 'solar panel' to heat the water and with a low volume pump regulate the temp under a propergation tray. Any advise is greatly appreciated. I have seen similar setups for egg incubators , fridge temp controls, etc. but need it at an allotment, so only power source is small panel. also if possible would it be possible to increase capacity of internal battery and have a heating element added. Thank once again. Leo

    ReplyDelete
    Replies
    1. I'll try to figure it out and address it soon, thanks!

      Delete
  80. I want to make my home theater wireless. My home theater model is Sony SRS-D9 2.1 channel. I also want the audio to be stereo. Range should me minimum 2 meters. Is it possible through Bluetooth module or RF transmitter & receiver? If so please suggest how to connect these modules to transmit and receive audio signals. If it is possible through Bluetooth then how to connect the bluetooth module to my home theater? If a small circuit is required I can make it on my own but for that I need the circuit diagram and specifications of components required.

    ReplyDelete
    Replies
    1. Rf transmitter/receiver is the easier option, but bluetooth could be much sophisticated, presently I do not have a bluetooth design, I'll try to find and update it soon in this blog.

      Delete
  81. Hello. U r working Great. Its really helpful for creating new things. I face a problem. Please reply my question .I have 12volt 5 amp battery charger. 12 v 4.5 amp acid battery. I want to run internet modem on battery. Modem values are 12v 800mAmp(mili ampere). Can I directly connected without any resister or other electrical instrument. My question is high ampare effect on modem? Will modem burn or dead due to high ampere? Also share some cutoff and control over charging circuits links..
    Regards

    ReplyDelete
    Replies
    1. Thanks very much!

      you can use the battery, the input current will not affect as long as the voltage is not exceeded beyond the modem's specified rating.

      Delete
  82. This comment has been removed by the author.

    ReplyDelete
    Replies
    1. Instead of making the resistor value low, you can make the capacitor value low...... reduce the capacitor value to much lower levels until the eyes are not able to detect the flashing.

      Delete
  83. This comment has been removed by the author.

    ReplyDelete
    Replies
    1. please show me the link so that i can see the circuit that you are referring to.

      Delete
  84. this circuit http://2.bp.blogspot.com/-ciHtiTzpAzM/U39a9XxtLAI/AAAAAAAAG94/Aa-lN3Vq_Wc/s1600/DRL+flasher+circuit.png

    i use 4 led with 1 ohm resistor , 3,2 V IF=30mA, but i use 2 of these in paralel soo if i use 50% duty cycle for both it shout be 60mA ?

    ReplyDelete

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