With this circuit it is possible to obtain a voltage of -5 V from a 5 V source. The circuit is from Radio Electronics from May 1982. The maximum current is around 80 mA.
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...