dc motor speed controller schematic

AC Motor Speed Controller Circuit

This triac-based 220V AC motor speed controller circuit is designed for controlling the speed of small household motors like drill machines. The speed of the motor can be controlled by changing the setting of P1. The setting of P1 determines the phase of the trigger pulse that fires the triac. The circuit incorporates a self-stabilizing technique that maintains the speed of the motor even when it is loaded.

220VAC Motor Speed Controller Schematic

dc motor speed controller schematic

For example, when the motor of the drill machine is slowed down by the resistance of the drilled object, the counter-EMF of the motor also decreases. This results to a voltage increase in R2-P1 and C3 causing the triac to be triggered earlier and the speed increases accordingly.

Related Products: Motors | AC Motors | Brushless DC Motors

Printed circuit board layout of the motor speed controller
motor speed controller pcb

Another version found here.

motor speed control

If the main use for this circuit is to control the brightness of a light bulb, RS and CS are not necessary.


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  • Vijendra

    do i need to make any changes for working with 240v cieling fan.
    and which value of l1 should be use also do i need Rs and Cs to be used also can i use BT136 and DB3 for triac and diac.

  • Ferry

    Dear sir, thanks for that particular circuit. But would you write down all of the right component for controlling the speed of bench grinder (250W,220V) ? and what type of the capacitor and resistor on that schema? if i want to put on-off saklar and electric socket, where should i place that component?

  • Mrunal

    Nice article! is this the same like controlling induction motor with TRIAC by triggering TRIAC with microcontroller and with variation of width of trigger speed is controlled?

  • engr feroz

    offff….it’s nice circuit…
    actually i need 220ac v in out fexid120v ac can possible?

  • mahesh

    It is very useful .how can make it the ac motor rpm controlling circuit do you answer me

  • Panjwani

    I want to replace potentiometer/P1 220K with single pole 4-5 step/way rotary switch for my old ceiling fan. Which Diac will match with Triac BTA10 or BTB10.
    Please suggest changes.


    sir i want a control circuit for 1HP,14440 RPM , 10 amps, 240 V single phase induction motor. can i use this circuit as it is ? or what changes will i have to do to make it work for my application? please guide me sir

  • karthikmula

    sir i want a dc series motor to speed varying motor output voltage we can vary the output speed.main problem is i should know how you designed the values of resistors and capacitors and potentiometer and inductor values in above circuit?. can we use it for speed control for induction motors

  • ashraf sayed

    really it is very usefull circuit but needs details i use it in washer machines AC motors.

  • ravish

    I want to make this circuit for household Motor about 200 watt….can anyone tell me…. What should be the components……will I use