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I need to put out 5 volts from an Arduino UNO digital pin. I've read that the pins can do approx. 5 volts, but I need to know if it will actually reach 5. I'm also powering a few other devices from the Arduino.

Are the digital pins capable of emitting 5 volts consistently? Are there any better alternatives? Thanks.

SeanM
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  • A 2n7002 MOSFET - 15 cents in 1's at Digikey wilol allow you to drive 50-100 mA wit =h no other parts (maybe a catch diode oj the coil). A BC337 transistor will drive hundreds on mA of load (needs one resistor). NEVER drive a relay directly from a processor pin - even if you can. Too much to go wrong - uC dies .... – Russell McMahon Jun 20 '15 at 13:58

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Your concern for the output capability of the pin should be its current sourcing or sinking capability, not its voltage. Arduino pins typically have a limit of 40ma per pin and a total maximum of 200ma. This is for the Atmega328p (you didn't say which Arduino you're using. You'll need to drive motors or relays or anything else with a substantial current requirement with a driver circuit powered independently of the Arduino itself. That can be with a shield made for the purpose or a circuit you design and build into your project. Motors and relays in particular need snubber diodes to protect the driving circuits from inductive "kickback" or spikes generated in their coils.

JRobert
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  • Note that the 40mA is the absolute maximum and isn't guaranteed. For sustained reliable usage you shouldn't exceed 25mA. Also the 200mA is the total for all IO pins combined. – Majenko Jun 19 '15 at 17:28