Found in a 90s Popular Electronics, this circuit provides sinusoidal signals at frequencies given by the components, as shown in the table beside the circuit.
This circuit triggers the LED when the monitored battery voltage drops below 9 V for 12 V...
We found this circuit in a Radio Electronics from January 1967. The SCR is already the C106, which...
This power source with silicon diodes at a time when valves were still used was found in Radio...