This circuit is designed as per a request made by Mr Vinoth from India. His requirement was a 12V/5A DC fan motor controller. I think this circuit is sufficient for this purpose. Quad 2 input Schmitt trigger IC CD4093 is the heart of this circuit. Out of the four Schmitt triggers inside the 4093, U1a is wired as an oscillator with adjustable duty cycle. The U1b, U1c, U1d buffers the output of the oscillator to drive the switching MOSFET Q1.The MOSFET drives the DC motor according to the switching pulse obtained from the oscillator. When R1 is varied the duty cycle varies and so do the speed of the motor. Diode D3 acts as a freewheeling diode.

Circuit diagram with Parts list.


  • Assemble the circuit on a good quality PCB.
  • IC U1 should be mounted on a holder.
  • U1a, U1b, U1c, U1d are part of the same IC CD4093; so power supply is shown connected only once.
  • The12V power supply for this circuit must be able to handle at least 5A.
  • A heat sink is recommended for Q1.


  1. chandrashekar

    Speed variation occurs only after certain angle of pot rotation.Not able to vary from 0-max
    Seeking your advice

  2. Sir, i have used this circuit to drive car wiper motor,motor stalls and starts rotate only above the half turn of pot.Pl can you inform the reason for this kind of behavior.

  3. I have assembled the circuit of fan regulator. I have put IRFP150 as mosfet. I am facing problem of mosfet heating up. my DC supply is 18 Volts and for CD4093 it is 12 DC. Can you help to solve the problem?

  4. Rajkumar

    Hi.. We are un employed engineering graduate.. In my team we are four member are trying to selfemployed our self. We are trying to impliment our ideas with some product.. For we need your help… We need 40 Amp dc motor drive for our product.. If u do this mean four people will get sure they lives.. So please try to help us and try to design a circuit for our requirnment.

    sorry for my My english, B.Rajkumar

  5. Hi, what changes would need to be made to control a 24 volt 900 watt dc brushed motor? If you can help buy giving me a wiring diagram and a parts list that would be great. Im new to motor controls and could use some help and fast! Thanks

  6. This circuit works well.

    1. What is the best low cost alternative for BUZ10 with low power as 500mA as Max load.

    2. Will it drive the driver transister if only one Schmitt trigger is used.
    ( since it is needed to drive 2 DC motors, have to use less compo)

    Quick reply appreciated

    • Seetharaman

      Hi Vivek you can use IRF540, IRF530 etc will suit well.

  7. Thank you for your electronic circuit posts!!!
    But i am interested to ask a help concerning how to control motors using mobile phone messages as i am look for it to do my final project.

    10 Q !!!!!!!!!!!

  8. shamu biswas

    i want a dc fan regulator circuit diagram which control 1-3amp dc ceiling fan

  9. NILANJAN ROY | 3 AMP 12

    actually i made a fan and its work fine with 3 amp 12 v transformer but when electricity have no , i wanna to drive its from 12/24 volt 15 amp of battery , my motor required 12 v 3 amp so please give me a circuit with available parts from run this 3 amp 12 v motor on 12 volt 15 amp of current

    • Seetharaman

      If is a 12volt 3amp motor you can use the above circuit itself. the supply may be capable of 15amp but your load requirement is only 3amps, hence no problem.

  10. Would you please give me a circuit same as above but for controlling a 36v dc motor and taking in a maximum current of 30A. I would be very thankful if you can help me.

  11. motiurmunna

    i want to control speed of a 230V 5a 0.75hp dc motor. please send me a schematic is very important for me.for the completion of my under graduate course.

  12. Hi
    Please would you be good enough to send me a schematic drawing and a list of components required for a speed controller, Which I would like to add to my wood turning lathe.
    The motor is 230v 1000w AC, if possible with a reverse.

  13. sir we have made a pwm circuit with 12v and it is working fine..we used a 12v motor and it is well controlled using pwm.but sir we want to control a 230v motor using pwm.can you tell me a method..

    thank you sir..

  14. Surya Prakash

    I am having the below mentioned phone set which went out of order recently, i tried to get the circuit diagram and other service manual to get this repaired. Unfortunately i did’t get it. will you please me help me in this regard any cost i am ready to pay also.

    1. I am having Nokia make cordless telephone which is went out of order few months back the details of which or as follows:
    Long Range Cordless Telephone Model NK 6150 CID
    (FSK/DTMF CALLER ID) Made in Finland.

    Eagerly waiting for your reply to my email

    thanking you,

    yopurs sincerely,

    surya prakash c n

    • Yo compré uno igual pare no se como funciona, me puedes decir???

  15. DerekOCUK

    I need a circuit to control the speed of a 230/240V dc motor, (separately excited field and rotor windings) which is driving an AC alternator. (need speed control to maintain accurate frequency on ac !)
    Please help

  16. Edgardo M. Diolola

    Dear Admin,
    I wish to have both functional circuits for 110VDC and 230VDC, 5 – 8 AMperes motors, using easy to find componenets / parts.
    Thank you in advance.

  17. I am using an owi 007 robot arm and I am trying to control it with a 2 phase dc motor with pwm and a dragon 12 board. The owi 007 robot arm has 5 dc motors that are each powered with 1.5V D batteries (1.5V power supply). Should I use a similar schematic in comparison with yours? If not, then what should I do?

    • Just replacing the MOSFET willnot do the job for you. For high voltages like 230V DC, you need a more efficient circuit. I will add one soon.


  19. Not really.

    I need the PWM and 12 volt Dc supply.

    Would putting suitable thermistor across either, from centre tap of pot to end or would it be better to use lower value pot and have thermistor in series at end.

    It’s for fan on this computer which is very noisy and isn’t needed at full speed all the time. Needs to keep pulse rate constant just vary the duty cycle. What is good/best pulse rate for such a fan.

  20. can u pls design nd telme the operation of..”a tamperature well as…..remote and manually operatable elctronic regulator”..connected to the same circuit for a single phase fan of “230volts..a.c” i suppose the current rating is 4 to 6 amps..i.e power rating of my fan is “750 to 1150 watts”..!!
    this circuit designed should be..applicable for high power rating of fans [like cooling purpose fans used in industries] …also proportationately increasing the…rating og electronic..components used in it!!..!! plz…provide ma the details..

  21. How would you modify this circuit so that the minimum speed can be set/adjusted and include temperature control so that if temperature rises the fan goes faster.

  22. can you please help me designing an electrical circuit with 230V input and output of 230v. even electronic components can be used

    • A simple bridge rectifier using BY127 diodes will rectify 230V AC.
      Pls let me know your application.

      For a good designing of such a regulator the designer must know the application.

    • A bridge circuit using high voltage, high current diodes like BY127 diodes will rectify 23OV AC.
      But what is your application.

      For a good design of such a power supply the designer must know the exact application.

      What is your required current rating.
      Do you need regulation.