This circuit was found in the October 1989 issue of Radio Electronics magazine. It drives an auxiliary relay with the call signal for a possible louder bell.
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...