LM3900 Rectangular Oscillator (CB25179E)

This 1 kHz oscillator uses a Norton LM3900 operating system. The frequency depends on C1 and R1 and can be changed.

Battery Low Indicator (CB4796E)
This circuit triggers the LED when the monitored battery voltage drops below 9 V for 12 V...
Capacitive relay (CB23765E)
We found this circuit in a Radio Electronics from January 1967. The SCR is already the C106, which...
Old power supply (CB23622E)
This power source with silicon diodes at a time when valves were still used was found in Radio...