We found this circuit for musical instruments in the March 1992 Radio Electronics magazine. The circuit has outputs according to the desired scale from a crystal oscillator at the indicated frequency.
Found in an old Popular Electronics this circuit is still current. The SCR can be of the 106...
This circuit simulates the signal produced by a muscle, serving to adjust medical equipment. The circuit...
Pressing S1 by a moment L1 glows up, remaining by a time interval depending on C1. This time...