If you are building your own hardware interface, you may desire to power your SBC off of a 12 VDC system, which is typical in ham radio, and not have to use a 5 VDC wall adapter. Here is a general circuit that should do the trick. This is known to work on the Raspberry Pi boards, but may also work on some of the other boards as well. If you are using something beside the Raspberry Pi, it is up to you to do the research to ensure that this will work with your board. You could fry your SBC if you are not careful.
On the Raspberry Pi boards, you can feed a regulated 5 VDC directly into the board via the GPIO header. It should be noted that, unlike the Micro-USB port, there is no regulation or fuse protection on the GPIO to protect from over-voltage or current spikes. If an incorrect voltage is applied, or a current spike occurs on the line you can permanently damage your Raspberry Pi. At best, you’ll “burn out” some or all of the GPIO pins, at worst you can fry your Pi! So be careful.
To power via GPIO, you only need to connect 2 pins:
- Connect a 5V source to Pin #2 (5V)
- Connect the ground of that source to Pin #6 (GND).
If you would like to see the full schematic of the design this is part of, please click this link: Full Schematic of SVXLink Card [PDF]