This alarm oscillator was found in the December 1974 issue of Radio Electronics magazine. The power transistor must be equipped with a good heat sink. The Frequency basically is given by C1.
This General Electric circuit was published in 1970. The LED is infrared and the voltage according...
This circuit was found in the October 1989 issue of Radio Electronics magazine. It drives an...
The transistor can be a modern equivalent and the transformer is the type of output found on an...