This circuit was found in a 1969 Motorola documentation. The FET admits an equivalent. The circuit has high input impedance and is powered by voltages from 6 to 30 V.
The frequency of this small transmitter, from a 1978 foreign publication, depends on the crystal. The...
This circuit from an old Motorola manual uses an integrated circuit that is no longer easily...
This circuit with RIAA equalization is from 1985 US documentation. The circuit has a flat response...