This circuit was found in a 1964 magazine, which no longer exists. It is a small wireless transmitter or microphone that sends its signals to a MW radio a few meters away. The microphone must be charcoal or low impedance magnetic. The coils are formed by 40 + 40 turns of wire 28 in a ferrite rod and the antenna is telescopic from 40 to 120 cm in length. The supply is made with 6 or 9 V and the transistor can be the BC558. R1 is 10k, R2 is 22k, C1 is 10 uF and C2 is an old MW radio variable.
