Found in the CQ radio amateur magazine, this circuit generates a standard 100 kHz signal. The circuit is from 1965 and can be made with modern equivalent transistors.
Found in the May 1971 Radio Electronics magazine, this is the circuit for a commercial...
Found in a Popular Electronics from the 90s, this circuit generates signals from 2 Hz to 30 kHz in...
This is one of the first radios with an integrated circuit. The circuit is from a Radio...