This well-known circuit version of the siren was obtained in a Colectro Handbook from the 70s. The transistors are of general use, with Q2 being a BD136 for greater power with power from 6 to 12 V.
Found with variations on this site, this circuit was taken from an American documentation from the...
This wide-range radiation monitor was found in a 1980s documentation. The circuit uses a diode as a...
This circuit was obtained from an Electronics World magazine from 1992. The circuit provides an...