This circuit of the 70's uses transistors of the time. The circuit can amplify signals from 10 Hz to 100 kHz and modern equivalent components can be used. The circuit is from Ferranti.
This circuit shows how we can take advantage of two old phones in a simple communication system. The...
This remote-control circuit was found in Radio Electronics magazine from June 1962. It drives a...
This AM micro-transmitter with power that can reach a few meters is from a publication from the...