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So this might be a total noob question (which admittedly I am) I have a Motor, if I connect it to GND and the 5V output it runs. Ok so far. But if I connect it to GND and a pin set to OUTPUT and HIGH nothing happens. My multimeter reads 5V for both setups, so if 5V come to the motor one way or the other why does one work and one not?

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That's probably caused by the motor's current consumption. The 5V pin can deliver much more current than the output pin in high state. If you want to switch the motor on/off by software, you need a "hardware driver" for the motor, in the simplest case a power transistor.

  • So you mean it is an Amper difference between the pins do you know what the limit for the output pins are – Victor Radu Apr 3 '15 at 12:14
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    40mA per IO pin. – Gerben Apr 3 '15 at 12:28
  • Be careful! You should't connect anything to the arduino pins, because you will burn them! It's better to use a transistor as @rolf said. Also add a resistance between the pin and the base of the transistor. – Stefa168 Apr 3 '15 at 12:54
  • That is what I always suspected. Transistors are not anything. – Wirewrap Apr 4 '15 at 7:05

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