The tracer, consisting of both a transmitter and receiver, is designed to follow a closed-loop wire or cable system. It follows an induced voltage path created by feeding a low-current, audio-frequency signal through the cable. When the pick-up coils come within close proximity of the current -carrying cable, a small voltage is generated in each coil, and that induced voltage is then processed by the receiver`s circuitry.
The circuit is built around a 567 phase-locked loop (PLL) configured as a variable-frequency, audio-generator circuit, which is designed to produe
-small.png "CMOS Circuits Tutorial")
characters left: