Found in a 1988s Radio Electronics, this circuit uses transistors of general use to increase the intensity of signals up to about 30 MHz. The power can be done by battery because the consumption is low.
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...