PWM DC Motor Speed Controller or Dial a Speed Controller


With out PWM DC Motor Speed Controller or Dial a Speed Controller difficult to speed control of DC motor. Most common problem in motorised project is the speed control of DC motor. It’s easy way to control speed of DC motor using a PWM DC motor speed controller or Dial s speed controller you can say also. So in this tutorial we will learn “How to make PWM DC motor Speed Controller or Dial a Speed Controller at home in easy way.

Mechanical or Robots runs on  DC motor it just runs only in continuous speed. Sometimes we have to use a mechanical gear box to reduce speed of DC motor. But in mechanical gear box can run in only fixed speed control also produce more noice disturbance. That can’t reduce also regular maintenance comes in role. And if you are DIY lover you should try this project most. We are introduce an PWM DC motor speed controller or you can tell a Dial a speed controller. You can search as a Dial a speed controller. Very compact design of this PWM DC motor speed controller. This built in very compact design with full dial potentiometer with back EMF protection, on board screwed terminal for input and output connection.

How it Works

Pulse width modulation (PWM) speed controller, using a 555 timer IC. 555 timer used as astable mode to control a N-Channel Mosfet. This mosfet actually switch motor on and off. PWM speed controller runs on 6-12 volt power supply. It means that 555 timer sanding pulses to the N-channel mosfet and mosfet on and off the DC motor. Sanding pulse means that amplitude is constant but it changes the frequency. DC motor speed controlling possible by changing pulse of the speed controller.

PWM DC Motor speed controller or dial a speed controller

You can easily understand how it works the PWM speed controller. So what do you mean by the frequency, It means how much cycle passes in 1 second. Suppose we are making a 12 volt PWM speed controller in that case our frequency is nearest to the zero point. Or you want to supply the 6 volt so you should set frequency at half range. From below image you can easily understand it’s working.

PWM DC motor speed controller, dial a speed controller

PWm DC motor speed controller, Dial a speed controller

This circuit simply designed to work. In pulse width modulation small pulse means lower power supply. Thicker pulse means higher power supply. By changing rate of change of pulse we can control the power. After completing circuit you can check by an oscilloscop. By this PWM controller you can generate square wave by 5% to 95%. Simple design and easy to built.

Building a Circuit


1. Vero Board

2. 6-12 volt 1A power supply

3. 555 Timer IC

4. 1N4007 Diode

5. 10K 1/4 watt Resistor

6. 220K POT with knob

7. 0.1 uF Ceramic capacitor

8. 100 uF Capacitor

9. IRFZ 540 N- Channel Mosfet with heat sink

10. Soldering type connector

11. Cooling pest


1. Soldering Iron

2. Hacksaw Blade/ Dremel Tool

3. PCB Drill/ Dremel Tool

4. Screw driver set & Plier

5. Wire cutter & Stripper

6. Multi meter



1. Cutting PCB & Layout

To make simple DIY electronics project in this project we are using a vero board to create circuit. First plot your components on PCB make draw layout on PCB. Then cut the excess PCB using a hacksaw blade. Make sure that also consider jumper wires in the circuit design.

2. Make Tracks

We are using a vero board, But vero boards are available in many ways. Some vero boards have a track and some boards have no tracks. Vero board used in this circuit has no track on PCB, so we are make tracks for positive and negative connections as shown in video. It is easiest way to create PCB.

3. Placing 555 Timer

We are using a 555 timer as astable mode install a 555 timer in centre of PCB make sure 1 & 8 pin facing to the positive terminal. Note that for safety precaution purpose we are using a 8 pin IC socket. So solder 8 pin IC socket in the centre of the PCB. Then solder pin no. 8 (vcc) and pin no. 4 (rst) to the positive track of the PCB. Next solder pin no. 2 (trg) to the negative terminal via 0.1 uF ceramic capacitor. Solder pin no. 1 to the negative track. Solder pin no. 5 (ctrl) to the ground connection via 0.1 uF ceramic capacitor.

4. 220K POT

We are using a 220K POT as a potentiometer. To  make connection of potentiometer solder pin no. 6 (Threshold) to the pin no. 2 as shown in circuit diagram. Then solder pin no. 3 (out) to the centre terminal of the potentiometer. Solder remaining two end legs via diodes to the pin no. 6 or pin no. 2 as shown in circuit diagram.

5. Installing Mosfet

IRFZ540 N-Channel mosfet used in this circuit to on and motor as controlled by the 555 timer. Pin no. 3 (Source) of mosfet solder to the ground track of the PCB. Pin no. 2 (Drain) of mosfet will be solder to the positive track via diode as shown in main circuit diagram. Next place 10K resistor between positive track and pin no. 7 (Disc) of the 555 Timer. Pin no. 1 (Gate) will be connected to the pin no. 7 of the 555 timer.

6. Input/ Output Connections

For input and output connection from the circuit we are using a soldering type connectors. Electrolyte capacitor of 100 uF placed at input connection of the circuit to remove ac components form the circuit. Both end of positive and negative terminal soldered to the positive and negative track. For the output connections positive connection form Vcc and negative terminal form the drain source (Pin no. 2) of the mosfet.

Important Note :

In this project we are using a N-channel high power and speedy switching diode. So during operation this diode release heat, so this mosfet must be installed with heat sink.

Hope you like this tutorial, You can also visit our YouTube Channel Weekend Fun. Have you any query please comment below also share with your friends and make it on weekend.


6 Replies to “PWM DC Motor Speed Controller or Dial a Speed Controller”

  1. Sir, the circuit diagram you gave is for operating up to 12V dc Motor. Can you please give a circuit diagram for operating 24V DC Motor controller which have 250Wt rating. This is required for operating 24V dc Motor for my cycle.

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