We found this circuit in the November 1985 issue of Radio Electronics magazine. It uses TTL technology and has binary inputs. The circuit must be powered by 5 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...