Raspberry Pi – POE – power over ethernet

I was considering using a Raspberry Pi for a weather station which got me thinking about remote mounting and how to power it.

POE controller for outdoor camera or wireless APAbout two years ago I designed and built some POE controllers for camera housings and outdoor wireless access points. These pass Ethernet through, take the power off the incoming cable  and provide fan and heater control where needed.

The incoming supply can be up to 24V-AC or 30V-DC. The on-board switching regulator efficiently drops the voltage  to a lower voltage; typically 9 to 12V DC. 9V minimum is needed to run the on-board circuitry for fan and heater control and suits many cameras and wireless Access Points. The Raspberry Pi needs 5V DC. There are 2 options: The tidiest, to assembled the controller to operate at 5V; requiring a 5V relay and fan. Or, a linear regulator used to drop 9V to 5V. The liner regulator losses would be about 1.5 watts but considering the small on-board fan there would not be a risk of overheating.

I’ll have to see if the weather station idea is practical. If it is, then assemble a box.

POE controller for outdoor camera or wireless API have already built a couple of outdoor wireless access points and outdoor cameras using this controller and it has worked well. So far surviving a couple of summers and winters outdoors mounted up poles.

The connectors are for a heating resistor which draws power direct from the unregulated POE supply and additional fans. The pin header is a programming port for the on-board micro that does temperature sensing and control. The green connector provides regulated power to the the camera, wireless AP or in this case could be a Raspberry Pi.

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