Gadget Design (RF Emitter?)

Thread Starter


Joined Jul 29, 2007
I'm trying to design a small gadget for a class project, and I was hoping to get some help with the necessary components.

Part I: I want something like 2 plates when they are in close proximity that can emit some sort of signal. (I was thinking maybe there is a cheap commercial form of something similar to RF id cards?)

Part II: I want another two plates which can pick up the signal from Part I if it is emitting and when these two plates themselves are separated and the other two plates are close a sound is produced.



Joined Apr 20, 2004
Your description is a bit hard to imagine. Can you expand on the concept of "plates"? To take a guess about something that might be satisfactory, google "theramin" for an idea.


Joined Jul 17, 2007
Er, it's "Theremin" there, beenthere ;)

That's your starting point - a Theremin (named after it's inventor.)

Google that, and look at the Wikepedia entry. See if it fits.


Joined Jun 30, 2006
You can hand wind a couple of coils, one coil is fed by low voltage AC and the other one goes to a speaker. You can even have the 2nd coil be powered by the ac and make it louder. It's not efficient but it works. Easiest is to light an LED.