We built the transmitter using a Colpitt's oscillator circuit and an amplitude modulator circuit. Using the Barkhausen criterion, we set the the oscillator's frequency by tuning capacitance values in the circuit. The AM circuit then modulates an input signal with the carrier wave coming from the Colpitt's oscillator, and the output is transmitted from the antenna. The circuit had a transmission range of several feet. Our design was first implemented in an LT Spice simulation, then tested in hardware and finally soldered onto a small breadboard. And of course we had to send proof of our working AM transmitter to our TA:
