Controlling a motor with a transistor

What are transistors

How do transistors work.


For NPN transistors
  1. Saturation.  Current flows from Collector to Emitter.  Occurs when the voltage of the base passes a threshold.
  2. Cut off.  No current flows from collector to emitter Caused when the voltage of the base is below another threshold (usually 0.6V)
  3. Active.  Output voltage is proportional to base voltage.  (Difficult to use with the Pi as we don't control the output voltage with the Pi).  Caused when the voltage is between 1 and 2 thresholds.
  4. Reverse Active (unusual state where the current goes from the emitter to the collector.)

Difference between NPN and PNP

Using the Pi to control the motor using PWM

Flyback diodes (Protection)



Trans BC548
Zerner 10V will do

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