Simple Motor Control
First, you're going to simply control the speed of a DC motor in one direction, using a power transistor, diode, external power supply (to power the motor), and a potentiometer (to control the speed). Any suitable NPN power transistor designed for high current loads can replace the TIP120 transistor.
The external power supply can be a set of batteries or a “wall wart” style external DC power supply. The power source must have enough voltage and current to drive the motor. The voltage must not exceed that required by the motor. For my testing purposes, I used a DC power supply that provided 5v at 500mA, which was enough for the 5v DC motor I ...
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