This circuit was found in documentation from the 1980s. Transistors are general-purpose types like the BC548 for NPN and the BC558 for PNP.
Found in Radio Electronics from the 90s, this siren finds many variations on this site. The...
This circuit appears elsewhere in this section, but taken from other sources. This is an English...
We found this circuit in the June 1991 issue of Radio Electronics magazine. The integrated circuit is...