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First off I have only very basics of electronic understanding, so I welcome any help that I can get. I have a Raspberry Pi that is powered off of the GPIO pins (yes I have read that this is bad and can fry the board). I still need the GPIO functionality but would like to power it externally - can I use the micro-usb port and feed it the required 5v? By this I mean using one of those wall adapters to micro-usb units.

If I use the micro-usb port, I guess I would need to cut the power feeding the GPIO pins at the 5v level. What about the 3.3v pin?

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    If you are supplying a sufficient amount of power through the micro-usb power supply, why do you need power into the GPIO pins? – syb0rg Sep 29 '13 at 17:07
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If you are planning to use the Micro USB port there is no need to also supply power to the GPIO pins.

You will still be able to use the GPIO pins for whatever purpose you required. Supplying power at the Micro USB port will provide power at the +5v and +3.3v GPIO pins to tap into if needed for your application, you do not need to supply your own.

In short the Micro USB port is designed to have +5v input and then regulate voltages for use across the rest of the board, and will present this at the appropriate GPIO pins at the specified voltages.

Supplying power to the GPIO pin(s) can be dangerous and is not recommended unless you know what you are doing and have a specific need. Doing so means you bypass the protective fuse and some other features, like the power regulators.

This other question/answer provides some useful information on supplying Power via GIPO. It also provides excerpts of schematics and explanation as to why power will be available at the GPIO pins if you supply power to the Micro USB port.

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The micro-USB port is designed to power the RaspberryPi using 5V wall adapters, so you'll be pretty much safe doing that. Moreover, that is the preferred way to power the RaspberryPi, widely used by millions of people around the globe, and as far as I know they haven't had any problem with that yet.

Regarding the external 3.3V supply -- I'd remove it, because the board is quite capable to provide the 3.3V from the 5V you feed through the micro-USB connector.

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