We found this circuit in the November 1992 issue of Radio Electronics magazine. The circuit has two integrated circuits, one of which is a preamplifier stage. The power supply must be dual.
The automatic modulated siren circuit shown in the figure really produces an interesting sound...
This circuit for incandescent lamps was found in a 70s documentation. The circuit uses an SCR...
In the figure we have a circuit in which two moving bar/dot indicators are connected together to...