This circuit for audio signals was found in the March 1990 Radio Electronics magazine. The circuit uses a unusual optocoupler that can be replaced with an equivalent one.
This shield circuit was found in an American publication from the 80's. The triac is of low...
In this circuit of a 1978 publication, the noise generated at the collector-base junction of any...
This circuit is from a year 2000 documentation. It generates pulses as fast as a battery or as...