This circuit uses two relays that switch when the voltage exceeds the value given by zener D2. The circuit is from a Radio Electronics magazine from April 1975.
Used in satellite TV receptions in the 1980s, this circuit was found in the March 1980 issue of...
In the figure, we show the way in which integrated voltage comparators of the LM139, 239, 339 and...
This interesting circuit shows on a display the sequence of numbers corresponding to a decimal from 1...