This circuit was obtained from the July 1970 issue of Radio Electronics magazine. Zeners are power types that can provide a good current to the circuit. Selection is made by rotary switch.
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...