Based on the BA1404 integrated circuit, this circuit was found in the July 1992 issue of Radio Electronics magazine. The circuit is short range, but a power amplifier stage can be used.
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...