We found this TTL power supply circuit in the December 1972 issue of Radio Electronics magazine. The circuit uses a 1 A transformer and the 2N3055 transistor must be equipped with a good heat sink.
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...