Found in American documentation from the 1980s, this circuit uses transistors from that time. It generates increasing and decreasing tones when we press and release the push button.
This circuit was obtained from an English magazine from 1979, but can be easily assembled...
The purpose of this circuit is used in communications and to respond to signals that are in the 2...
This circuit was found in the November 1989 Radio Electronics magazine. Power supply depends on...