This is a PoE (power over ethernet) extractor with a DC-DC converter. You plug in a cable carrying data and 48VDC, and you get a clean, regulated 5VDC output and a standard RJ45 jack. I designed the board with Cadsoft's Eagle: the schematic, layout and Postscipt are all here.
This board uses the Cisco wiring model (positive power on pairs 7,8, negative power on pairs 4,5).
|The sockets are Jameco part number 167290. $0.39|
|The 48V to 5V DC-DC converter is MPJA part number 14131, specs from Artesyn. $7.95|
(This PoE board is the one in the wireless repeater, here).
I recently sent off to have some boards made. This is the result.