This receiver for listening on the phone was found in a Japanese magazine in 1967. The circuit uses germanium transistors, and the coil has 10 + 50 + 20 turns of wire 28 to 32 in a ferrite rod. Power is provided by two 1.5 V batteries.
This receiver for listening on the phone was found in a Japanese magazine in 1967. The circuit uses germanium transistors, and the coil has 10 + 50 + 20 turns of wire 28 to 32 in a ferrite rod. Power is provided by two 1.5 V batteries.