The circuits below (transmitter and receiver) were used in old TV sets of the years 50 and 60. The circuit is inductive and have some meters of range. The transmitter’s coil is formed by 50 + 20 + 20turns of AWG 32 wire on a ferrite core and the receiver’s coil is formed by 200 turns of 28 AWG wire on a ferrire core. The transmitter is powered from a 9 V battery. The relay controls a motor that selects the tuned channel.
