We found this circuit in the May 1989 Radio Electronics magazine. The circuit can have its values changed to operate at other frequencies and the power supply must be symmetrical.
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...