NE555 based PWM DC Motor Speed Controller Circuit with PCB Layout

Written by Prithwiraj Bose on . Posted in Hobby Centre

In this article I will show you how to create a NE555 Timer IC based PWM DC Motor Speed Controller. I will share the circuit diagram, component list, tips for making the circuit yourself and a fully working Printable PCB Layout. You can fabricate your PCB with this layout and make the circuit easily. This is one of the most common circuits of my Electronics Hobby series.



Circuit Diagram of Motor Speed Controller

Following is a working circuit diagram of the NE555 PWM Based DC Motor Speed Controller.

NE555 DC Motor Speed Controller Circuit Diagram


How the Motor Speed Controller Works

In this circuit the NE555 timer IC is configured to generate square wave. The capacitor C2 gets changed and discharged through the output pin i.e. pin 3 of the NE555 timer. C2 charges through diode D1 and discharges through diode D2. The potentiometer VR1 defined the rate of charging and discharging thus the duty cycle of the PWM output.

The discharge pin i.e. pin 7 of the 555 timer IC is used to drive the MOSFET by generating PWM, instead of its usual purpose. It pulls down the MOSFET Gate during the discharge cycle of the circuit. The 1K resistor, during charge cycle pulls the MOSFET Gate back to high. Thus the MOSFET controls the speed of the motor, effectively driven by PWM Signal.

Note that there is a contradicting version of the circuit on the internet, where pin 3 and pin is just used the opposite way than how it is used in my circuit diagram. Rest assured that both of the circuits work. Pin 3 and Pin 7 of NE555 are almost equivalent to each other. The only difference is, pin 7 is an open-collector, while pin 3 has a totem-pole output. The 1K resistor is connected to pin 7, and it pulls up the MOSFET Gate to high, which eliminates any difference between pin 3 and pin 7.


PCb Layout of Motor Speed Controller

The images shown below are scaled down to fit this page. Click on the images to open the actual-sized version of the PCB Layout images. Do not change the size of the images while printing. Alternatively you can use the printable PDF versions of the PCB Layout (download link given below these images).

Copper (Bottom) side
NE555 DC Motor Speed Controller PCB Layout Copper Side
Silk Screen (Top) Side
NE555 DC Motor Speed Controller PCB Layout Front Side

Download the Printable PDF of NE555 based Motor Speed Controller PCB Layout
NE555 based PWM Speed Controller PCB Layout – Copper Side
NE555 based PWM Speed Controller PCB Layout – Top/Front Side

Buy the components required to make this circuit from an online electronic components shop and start making now! For any help, do not hesitate to contact me.

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Prithwiraj Bose

I am an Architect of Distributed Applications of Information Services Industries in TATA Consultancy Services Ltd. I live in Kolkata, India. I love computers, programming, travelling and singing. Photography, spending time with my aquarium, designing a random website, painting, and singing are my favorite pass time. I've recently grown interest in Electronics, IoT and Robotics.

Comments (2)

  • electron123


    What’s the watt of the Motor ? Pls


    • Prithwiraj Bose


      The Motor which I tested with was 20 Watts. Continuous Drain Current of IRF540 is 28 Amp. Simple math suggests, at12 volt, it is expected to withstand a 336 watt motor’s load. But you need a BIG heat sink to apply such a huge load. But the PCB layout given here would not allow you to accommodate such a big heat sink, if you solder the MOSFET on the board. You have to connect the MOSFET with wires to the board to attach the heatsink.


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