This circuit is an alternative version of the previous one also found in the July 1995 Electronics Now magazine. The triac must be equipped with a heat sink.
This circuit uses common CMOS components. We found it in the July 1987 issue of Radio Electronics...
The L7805 is the SGS equivalent of the 7805. The circuit is from the SGS linear integrated circuit...
A modulated (flashing) siren using the four gates of the 4001 integrated is shown in the figure....