Used in satellite TV receptions in the 1980s, this circuit was found in the March 1980 issue of Radio Electronics magazine. Note the board layout.
The oscillator in figure 1 can be used in alarm, call or warning systems, producing a sound of...
This circuit is from a 1973 documentation. In it we have the way of using a FET as an input of...
This circuit is for traditional old-style telephone lines found in an American 1980s...