)
This variable frequency oscillator was found in an old American documentation. Transistors allow more modern equivalents and coil data are found next to the diagram for several frequency bands.
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...