Greenlee 2007 Closed Circuit Tracer & Wire Tester

I doubt it's very interesting- just a high-Z capacitive pickup. It's keeping 60Hz out of circuits that gets interesting.

Best regards, Spehro Pefhany

As Spehro notes, it really isn't that interesting. A DVM can do this, especially when you don't want it to.

Don't trust it to tell you that a circuit is dead. A false negative can leave you dead.

"The Journey is the reward"

eff.com

This system consists of two parts. The transmitter plugs into a live AC circuit. This transmitter is small - no larger than a typical 'wall-wart'. The receiver is an inductive type pickup that one can scan near/over the circuit breaker box (or wire) near the circuit being monitored and gives an indication when close to the circuit that the transmitter is plugged into. I would be curious as to the transmitter circuitry - as to frequency(ies) used and how it is coupled into the live AC circuit.

TomC