With this circuit it is possible to control the intensity of a signal digitally. The circuit is from Radio Electronics from February 1981. The power supply must be 18 V.
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...