The Transmitter (Tone Generator):
Connects directly to the target wire using alligator clips, an RJ45, or an RJ11 plug.
Injects an alternating high-frequency electrical signal (a "tone") into the conductor.
The Receiver (Inductive Probe):
A handheld unit with an insulated, non-conductive tip, built-in speaker, and sensitivity dial.
Uses electromagnetic induction to detect the signal emitted by the wire without requiring direct copper contact or stripping insulation.