Thank you for your reply.
I have main reason:
common wireless keybords are too expensive for me and dont fits me (i like my wired)
and i want to decrese amount of wires on my table.
I am using notebook, so if wireless keyboard stops working I can use notebook's keyboard.
I searched for some bluetooth adapters, but nothing? So how can I do this? Where can I start?
Okay, if you insist. I would start with an existing wireless keyboard and its matching receiver -- try and adapt the wired keyboard of your choice to work with the wireless parts.
I have a Bluetooth mouse, somewhere, so I assume that technology is also used for keyboards.
Incidentally, in my view the only keyboards worth a damn are the original IBM PS/2 models -- I've used these since the early 1990s and the one I'm typing this on was actually built (in Scotland) in 1987.