We found this circuit in a Japanese 1968’s documentation. The circuit makes use of transistors from that country common at the time of publication. Observe the symmetrical power supply for the circuit.
This transmitter has a range of a few hundred meters depending on site conditions. The coil...
The circuit shown below was obtained from the National Semiconductor Linear Applications Handbook...
This circuit was found in a Popular Electronics from the 90s. The circuit has 4 frequency ranges...