You can salvage some nice motors out of optical drives but they can be tricky to control ... His test circuit uses six 2N2222 transistors to protect the Arduino from excessive current.

So I needed a way to map the RC receiver’s two sets of motor control ... on the PNP transistor. A positive signal would then go from the battery, through the transistor to the Arduino.

ClearCore CLCR-4-13 is an industrial IO and motion controller that can be programmed using the Arduino IDE. It handles up to four axes of step-and-direction motion control (500kHz max step rate), and ...

In this quick Arduino tutorial I will explain how you can control a relay using the Arduino Board, one 1K and one 10K resistors, 1 BC547 transistor, one 6V or 12V relay, one 1N4007 diode and a 12V fan ...