For a remote control project, I am interested in building a simple AM radio receiver like those used on toy cars. I would like to use a pair of crystals to do the tuning of the transmitter and receiver circuits. The transmitter is easy, Ill just use a simple circuit like a collpits oscillator. The receiver, however, really confuses me. I have no idea how to take a simple crystal and make a tuned circuit with it to receive a radio signal, and then say, turn on a transistor whenever a signal is present on the crystals resonant frequency. Any help?