In this project guide we’re building PWM Motor Speed Control circuit using two digital IC’s. We’ve published different types of PWM circuits, say from the basic PWM using NE 555 IC, to the much advanced PWM using micro controllers like AVR, 8051, and Arduino boards.

PWM – is basically pulse width modulation and if you’re new to this – please go through our basic guides – Pulse width modulation  and other PWM articles.


Here is a simple PWM motor speed controller circuit that can be used for varying the speed of low power DC motors . The variation in speed is achieved by varying the duty cycle of the pulse supplied to drive the motor. Of the two gates of IC CD40106B , N1 is wired as an inverting Schmitt Trigger astable multi vibrator for producing pulses and N2 as an inverting buffer to drive the transistor during positive cycles at base. The duty cycle is set from resistor R2. R1 limits the base current of transistor SL 100. The circuit is ideal for controlling toy motors,hand held mini fans , small blowers etc.

PWM Motor Speed Control Circuit Diagram with Parts List.

PWM DC Motor Speed Control
PWM Motor Speed Control Circuit Diagram

Notes .

  • By varying R2 duty cycle can be varied from 0% to 100%.
  • For identifying pins of SL 100 ,the pin that is connected to casing is collector,the pin near to notch is emitter and the one remaining is base.

We have more Motor Control circuits that you may like to read, please take a look below:

1. PWM Motor Speed Controller Circuit

2. Stepper Motor Controller

3.  Temperature Controlled Fan

4. Bi-Directional Motor

5. Stepper Motor Driver Circuit



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  2. Isyaku S. Kwaru

    Hi, Your simple circuit is so impressive.

    • Seetharaman

      Hi Divya it is a hex Schmidt and housed in 14 PIN DIL package. each schmidt has one input and one output. 6 X 2 =12pins plus 2 for supply hence 14 pin package.

  3. Hi, can you please list some alternatives on the parts CD40106B and SL100? My two local stores don’t have those exact items in the offering, but do have many similar ones…


      Hi, You can use 74HC04 and TIP122 instead of CD40106 and SL100 respectively.


        40xxx series is CMOS technologies so it will give better result. However 74HC04 will work fine.

  4. Thank you so much to give me acircuit diagram thats why my project is made easily. so please give me a new circuit diagram on my e-mail ID.