Our next circuit consists of an FM transmitter having a slightly greater range than the CIR24101. Here, the components are commonplace, and only the connection of the transistor and the electret microphone should be observed. The coil is formed by four turns of common wire on a ferrite core. As in the previous circuit, the length of the antenna can be between 1 and 20 cm and the wire used can be any, as long as it is self-supporting. Button batteries can be used, which gives the assembly a very small final size.
