This circuit has more power than the previous one, since it includes a powerful transistorized stage. The circuit is from Radio Electronics from July 1985. It includes the power supply.
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...