distant alarm

[farshad_momtaz]

hi,

i want to make a 2 electronic boards that if 2 peaces get about 20 feet apart one of them do something(for example turn on a LED or start an alarm)
i was wondering where should i begin? and is there any electronic board design out there that can do that?

thank you

 

[blueroomelectronics]

What are "peaces"?

 

[farshad_momtaz]

i meant the electronic boards.(2 boards)

 

[blueroomelectronics]

A 20' bit of string that pulls out a plug on one or both of the boards.

 

[farshad_momtaz]

thanks for ur answer and nice idea, but i don't want it to have a wire between two boards.
any other ideas or ways to do this?