This circuit, found in 2002 documentation, triggers LEDs when a phone call is received. The LEDs will flash alternately in these conditions. Common LEDs are used in this circuit.
Twin-T oscillators can be used to produce sinusoidal signals in the audio track with good...
This circuit generates three outdated signals whose frequency is given by the time the signals...
We found this circuit in American documentation from the 1980s. Transistors can be of general use....