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.
The MOS field effect transistors of this circuit are not very common, as it is a project from the...
This old circuit uses na operational amplifier not easy to find in these days. But the circuit can be...
This circuit consists of an astable multivibrator whose frequency changes according to the light...