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.
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).
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.