The goal of this project was to build a small, cheap, light-weight transmitter to attach to a small bird.
The circuit shown was originally designed by William Cochran (1), with modifications by Charles Walcott.
Physical layout of the circuit
A test version of the circuit was constructed in a 5x2 chunk of IDC female header plug so that the crystal and transistor could be easily changed. The tank coil can be seen on the right in either photo below. The brown/white wire to the right is the antenna. Power supply leads extend to the left.
The final circuit version was built using the crystal as the physical substrate.