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.

Transistor Amplifier (CB18859E)
This circuit from a Japanese publication in 1968 uses germanium transistors from the time like the...
Current indicator (CB22132E)
In this circuit the voltage across the LED is limited by the diodes. The maximum current also...
Low hysteresis comparator (CB6085E)
Obtained from a 1980s Linear Technology documentation, this circuit has a hysteresis of less than...