Here is a circuit that helps you test cable continuity without requiring any physical contact with the bare cable. This circuit detects AC signal frequencies and gives an LED indication if the cable is conducting. This circuit is highly sensitive and can detect signals from the surface of the cable itself and thus no direct contact with the bare cable is necessary. The circuit can be used to test other wires, including modem, audio/video and dish antenna cables to name a few.
|Fig. 1: Circuit of cable tester|
TP2- Amplified output corresponding to the input signal