PoE network question

Hi all,

I'm getting informed on PoE equipment. I learnt there are poe injectors, switches and splitters. I'd like to poe-enable my existing network, so that i'll be able to power up my arduinos without other plugs. My question is:

is it possible to use a single injector (like this: http://poeinjector.com/ ) to power-up a small local network (given I won't exceed injector's wattage)? I mean without using a poe enabled switch/hub, by just connecting the injector to my existing 4 port router. I don't want to buy 4 separated inline injectors neither a midspan like this:

Thank you

I'd like to poe-enable my existing network, so that i'll be able to power up my arduinos without other plugs.

If you are rolling your own DIY PoE setup, you can wire your lan devices for a 10baseT four wire connection and run a DIY power setup over the other four wires in the cat5 cable.