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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.

85 Comments

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  • jon-matiszyahoo-ca

    just wondering what the values would be for 120v mains and 1hp motor?
    I’m going to try to convert a washing machine universal motor to a wood lath drive.

    thanks

  • ArBiNd

    if my P1 is set to a fixed resistance R, will the motor speed be the same for different ac input e.g 220V & 190V?

  • Nikhil

    which triac and diac should I use for 2000W heater load,and also value of capacitor. provide ckt if possible

  • suleiman

    Why the diac , what is the function,

    • Jim Keith

      The DIAC is a triggering device –it blocks until the voltage across it exceeds about 28V –at this point, it breaks over and dumps the charge stored in C4 into the TRIAC gate. This provides a high current, fast rise time gate pulse.

  • pasan

    hi sir ……. ! this circuit can be drive 1hp or 2hp motors …?

  • Hossam Zayed

    I’m building a project that requires a device to control a 3 phase induction AC motor 1.5 kw and 1400 rpm to do the following
    1-reverse Motor direction
    2-switch motor on/off (frequency up to 1 time per second)
    3- Can be controlled by a micro controller (i.e accepts digital signal)
    No need for controlling motor speed
    does your circuit design provide the control device I’m looking for?
    thanks and waiting for your kind reply

    • Jim Keith

      This circuit is for single phase applications only. I will soon post a circuit that will control a 3phase motor.

  • 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 10amp.how can possible?

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