This siren configuration found in a documentation from the 1980s can also be seen in many of our projects and in this circuit bank. Transistors are common, but Q2 can be of power for a higher voltage supply.
We found this circuit in the September 1971 Radio Electronics magazine. The SCR can be any of the...
This circuit uses unijunction transistors and drives a small speaker through an output...
The circuit presented was found in the Motorola Linear Databook of 1990. The power supply is...