First of all I asked this question in DIY.stackexchange.com, because of the cabling in the house. Here I would like to ask about the electronics (or electrical) part of it.
And there is a very similar question here: Powering multiple devices from a single power supply
Yet there are some differences. First of all I was thinking to use 48V to transfer energy from a single power DC adapter, which I would like to place next to the main ethernet switch. Then I want to make a simple board, where I will split 48V DC output to 4-6 parallel wires. I would like to wrap these wires around Cat6 cables with tape (Cat6, because price it much higher for 50m cable, it is a good investment for the future and I don't want to replace these soon) and pull these combined cables through the walls (by replacing currently existing phone line or cable TV both of which I am not going to need).
My goal is here to provide 3 rooms with a pair of ethernet. One for personal computer or TV and the other one for a Raspberry Pi, which would run either as media center or security camera.
PoE is a more expensive alternative. I would like to use a gigabit switch for the future. Raspberry Pi's only support 100M but next model might be 1000M already. TV and PC's should definetely have 1000M. PoE switch 8 port is +100€s, 4 port is +50€. Then I need splitter for each Raspberry Pi (~4x), which is additional +60€ in total.
Since, I am enthusiastic about electronics, I thought I might try to do something on my own and learn more about it. So a single 48V power supply and wires around Cat6 around the house would solve my problem. Then I can solder my own small voltage regulator board. Which is even better, because I would like to attach infra red LEDs to my security cams, which will draw additional energy. My understanding is to feed them extra, since Raspberry Pi has a limited output energy. I can create the board in a way that the LEDs are controlled with a transistor (MOSFET?) and are fed with an extra voltage regulator (6V or something).
I know there are many aspects in this problem and I could split into different questions, but my original problem is to feed Raspberry Pi's with less adapters/cables as possible and with least costs. Is this possible at all? Do you think, this would be the optimal solution? Are there simpler ways to power my Raspberry Pis?
Here is a schematic: