This vibrato circuit was found in Motorola's 1966 documentation. The circuit uses transistors of the time that can be replaced with current common types. Power is done with 3 9V batteries.
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...