SCR DC motor speed control circuit using IC-CMOS

This is speed motor controller circuit of 12V DC motor. as SCR DC motor speed control circuit  using  IC-CMOS. You can adjust the speed of rotation of the spindle motor from 5-60 cycles per minute.

How does it work
To begin with, the 12V AC voltage from the Secondary of transformer comes to bridge diode-BD1. It rectifies from AC (Alternating Current) to DC (pulsed DC).

SCR DC motor speed control circuit using IC-CMOS

SCR DC motor speed control circuit using IC-CMOS

This can use for DC motor and SCR1—The SCR needs to use DC to A-K lead—. Which uses just the pulsed DC only.
But we also use digital IC.

Cr: Photo Power SCR Bridgold

Second, we use one nand gate CMOS-IC, CD4081. It requests a stable power supply to pin 14. The D2 gets the pulsed DC to filter to smooth DC current with C2-220uF.

The pin 1 gets the pulsed DC directly. And the other into pin 2. Next, The VR1, C1, and R1 are the phase shift circuit to delay the pulse DC to slow down.

After that, the pulsed DC from pin 3 to triggers the gate of SCR1 turns on.

The working of SCR like switches on-off the pulsed DC to the motor, makes it rotate. The Speed of the motor can adjust by VR1.

If pulsed DC has “high” state more than “low” state. It makes more current to the DC motor, it rotates very fast.

But in the opposite way, the “high” less than “low” state. It rotates too slow.

The D1 prevents the noise from the motor.

The D3 is a reverse-voltage protection of motors. This can cause circuit damages.

If the circuit uses to the high power motor. You need to install a large heat sink to BD1, D1, and SCR1. Because they are very hot, may damage.

‘12V DC Motor Speed Controller using 4011’ »

How to builds
This project is easy because use a few parts. For faster to build if we assemble this circuits in the Universal PCB in Figure 2 is components layout for a guide.


Figure 2 the components layout of the DC motor controller diagram with SCR and cmos IC.

The components lists.
IC1___CD4081___CMOS Nand gate IC
SCR1___SCR-C106D or equivalent
BD1____Bridge Diode 6A 200V
D1_____1N5401___3A 100V diode
D2,D3__1N4004___1A 400V Diode.
T1_____Transformer 3A 12V
C1_____1uF 16V Electrolytic capacitors
C2_____220uF 16V Electrolytic capacitors
VR1____5K potentiometer
R1_____5.6K____1/4W resistors

PWM DC motor controller with NE555 »

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  1. Daniel

    I need a 12v 5A dc motor controllers please help me?!

  2. rahul

    in DC MOTOR CONTROLLER DIAGRAM WITH SCR AND CMOS IC what would be the capacitor value for both capacitor.please give the reply as soon as possible.

  3. sadaf

    i need a circuit diagram of DC motor with trnsformer, regulator, diods, rectifier.

  4. Jay

    The output of the NAND is only two states – logic 0 or logic 1, how will this allow a continuous variation?

    Because by adjusting the potentiometer, we can only have output of NAND (Thyristor gate signal) as high or low.

    • augusto ferreira

      the secret is on half wave rectification ,when goes high charge c1 when goes low discharge c1 like zero crossing regards

  5. muhammad ali

    this circuit is working and good one>< thanks

  6. know it

    how the ic controls the speed of the motor please sir explain

  7. gopinath

    this circuit is working good thank you admin of this post

  8. farhad

    pleas tell me how much current rating of 12v dc motor use in DC motor controller with SCR and cmos ic

  9. Bekele

    please let me know 48 dc.v forklift motor speed control SCR control system


  10. bharti singh

    give me every detail of all the components used in this model

  11. Faneshwar Patel

    how the ic controls the speed of the motor please explain..
    and also current rating of dc motor….

  12. dk

    frnd mene ckt ko sahi design kiya pr motor nahi gumi
    pls guide me

  13. samrat m

    sir i want control a dc motor in four quardints
    plz explain and guidme

  14. md ali

    this website is very usful for engineering student and also like me
    hello sir i need a pcb layout of speed control of dc motor by using scr or cmos ic
    pls send me its layout

    md ahshan ali

  15. Kanhaiya

    Pls explain the work of IC in above circuit.

  16. sapna M.

    I have designed circuit as per given circuit diagram;but it is not working…
    The variation in potentiometer is not controlling speed of dc motor….

  17. ravali

    sir plz tel me the speed control of 12v 5a dc motor is compulary required heat sinks kadha ela connect cheyali circuits lo and rating of heat sink entha

  18. Hamza Bashir

    could you please send me the PCB lay out of this circuit…..i really need this for my semester project

  19. Hi
    thank you for the above circuit.
    can the circuit be up scalled to carry high voltages and current; say 250 dc at 100 A?

  20. kalaiarasan

    Can any one say the application,merits and demerits of this circuit….

  21. VISHNU


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