This somewhat complex circuit was found in the May 1984 issue of Radio Electronics magazine. The circuit drives a power stage with a triac for loads connected to the power grid.
The automatic modulated siren circuit shown in the figure really produces an interesting sound...
This circuit was found in the August 1973 issue of Radio Electronics magazine. The Darlington...
This circuit has three settings, central sound frequency, modulation speed and modulation depth. The...