Signal Tracer

Posted on Aug 29, 2012

A simple test circuit to fault find audio and radio equipment. Can be used to inject a square wave signal, rich in harmonics, or used with headphones as an audio tracer. A single pole double throw sitch is used to switch between inject and trace modes. The diagram is drawn in trace mode, the earpiece being connected to the collector of the last transistor. Both transistors are wired as emitter followers, providing high gain. DC blocking is provided by the 1n capacitor at the probe end, and the two stages are capacitively coupled.

Signal Tracer
Click here to download the full size of the above Circuit.

When the switch is thrown the opposite way (to the blue dot) both transistors are wired as an astable square wave generator. This provides enough harmonics from audio up to several hundred kilohertz and is useful for testing AM radio Receivers.

Leave Comment

characters left:

New Circuits



Popular Circuits

Luh & Yang
Oscillator circuits
Current mirror
HP 200LX USB / Power Supply dongle
Simple Ring Modulator
Home-made high-performance four-dimensional surround sound amplifier circuit
Ultra High Sensitivity Metal Detector Circuit