Tests PWM speed control of a DC motor.
Here’s a quick video of the circuit in action:
Demonstrates using a PWM signal to control the current driving a DC motor, hence its speed.
The small PWM signal is amplied 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.