Found in an American documentation from the 90s, this circuit uses small low voltage lamps (6 to 12 V0. The circuit can be adapted to use LED indicators.
This circuit is from a 1979 publication. The sensor consists of plates or screens that, when...
The circuit is from a Radio Electronics from August 1989. The cells used at that time did not have...
The automatic modulated siren circuit shown in the figure really produces an interesting sound...