The circuit we presented was obtained from a 1965 documentation, consisting of a small AM transmitter for the medium wave range, with a range that reaches a few tens of meters. The frequency is determined by the two coils which basically have 100 turns of wire 28 in a ferrite rod. In the original design a commercial coil is used that can hardly be obtained nowadays. In addition to the tube the other critical component of the design is the power transformer. In the circuit, we have the way to connect the audio input to an external audio amplifier for retransmission of music, for example. However, the signal source can also be a microphone.
