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.
This circuit makes use of a special LM195 power transistor not very easy to obtain. The circuit is from...
Found in documentation from the 90s, this circuit can employ other comparators in the series such as...
Suggested by Philips in a 1970 publication, this circuit uses components from that time. No...