Found in a 90s documentation, this circuit makes use of D1, a switching diode that is uncommon today. D3 is an LED. The circuit monitors 12 V batteries.
This circuit appeared in the 1991 Electronics Experimenter Handbook. The circuit is for remote...
This circuit was found in Radio Electronics magazine from January 1959. The power transistor must...
This circuit uses an MW radio tuned to around 540 kHz to detect atmospheric signals, for example, from...