Found in Popular Electronics from the 90s, this circuit uses a reed switch on the rails as a sensor. Instead of lamps, in a modern version, LEDs can be used.
This circuit for the 1750 m band was published in the September 1989 Radio Electronics magazine. The...
The purpose of this circuit is to disconnect the battery in case of an excessive charge current,...
This circuit was originally designed to operate with the alarm CIR12065 which has a tone output. It...