This circuit was found in documentation for radio amateurs of the 1980s. This is the so-called roger-beep, which is the beep that is transmitted when the talk-listen function is changed.
Found in an English documentation from 1989, this circuit uses components common today. The...
The LED frequency flashes depends on the value of the capacitor tested according to the table. We...
Found in a Popular Electronics from the 90s, this circuit generates a signal that depends on the...