Tunnel diode simple noise generator (CB23705E)

This circuit was found in Radio Electronics magazine from November 1960. The circuit is powered by a photocell of the time.

360 degree phase shifter (CB8159E)
This circuit consists of two stages that each shift 180 degrees the signal. The circuit was...
Battery Tester (CB16738E)
This simple battery tester uses two transistors to drive LEDs of different colors, indicating the...
RIAA Line Drive Amplifier (CB8932E)
Found in 90s documentation from Analog Devices, this circuit employs operational amplifiers of the time....