This circuit for communications receivers was found in the January 1974 issue of Radio Electronics magazine. The transistors are Japanese types of the time, as the circuit was part of equipment of that origin.
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...