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 circuit was taken from recent English documentation. The circuit uses a 500 uA microammeter as an...
Found in Popular Electronics from the 90s, this circuit uses a reed switch on the rails as a...
This filter for scratch and rumble noises that occur on turntables was found in the February 1995...