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Project Notes

#046 PWM Motor Control

Testing DC motor speed control using an Arduino-generated PWM signal.


Here’s a quick video of the circuit in action:

MotorControlPWM demo


Demonstrates using a PWM signal to control the current driving a DC motor, hence its speed.

The small PWM signal is amplified with an NPN transistor. An S9013 transistor is used in this case, primarily because:

  • it has relative high hfe(β); for class H it typically ranges 144-202
  • supports a decent continuous collector current (Ic) of 500mA (the motor I’m using is rated at 150mA)

A fly-back diode is placed across the motor to drain any voltage spike as the motor load is switched.


The Breadboard

The Schematic


Credits and References

Project Source on GitHub Project Gallery Return to the LEAP Catalog

This page is a web-friendly rendering of my project notes shared in the LEAP GitHub repository.

LEAP is just my personal collection of projects. Two main themes have emerged in recent years, sometimes combined:

  • electronics - usually involving an Arduino or other microprocessor in one way or another. Some are full-blown projects, while many are trivial breadboard experiments, intended to learn and explore something interesting
  • scale modelling - I caught the bug after deciding to build a Harrier during covid to demonstrate an electronic jet engine simulation. Let the fun begin..
To be honest, I haven't quite figured out if these two interests belong in the same GitHub repo or not. But for now - they are all here!

Projects are often inspired by things found wild on the net, or ideas from the many great electronics and scale modelling podcasts and YouTube channels. Feel free to borrow liberally, and if you spot any issues do let me know (or send a PR!). See the individual projects for credits where due.