I want to build a simple crystal radio receiver. I do not want amplify the signal received. I want to detect the presence of a transmitted signal, and then use the presence of the received signal as a trigger to switch on another device (battery powered). My knowledge is VERY basic, and I have been trying to learn more. I have found a schematic on the web.
Is this design suitable for my intended purpose? (minus the Earpiece) From what I can tell, this receiver is made up of an inductor, a variable capacitor, and a diode. I am assuming my circuit would need a transistor switch as well. What else would I need? (I have assumed here that the antenna is part of the inductor coil - is that correct?)
I am looking for components I can use to make up this circuit. I want to receive the signal across a range of 60 feet and I want the circuit to be small (>1cm). What else do I have to ascertain in order to start searching for the components I need?
If anyone can to suggest suitable inductors, capacitors and/or diodes - this novice would be grateful!