While troubleshooting amplifier and audio related equipment, a signal injector circuit becomes one of the most essential tools, here we learn how to make a signal injector circuit.
Here is a two in-one test instrument incorporating a signal injector and a signal tracer. If any audio equipment is not working, an audio signal can be injected at the volume control using this instrument. lf audio signal appears at the speaker of the set, you can be fairly sure that there is no trouble in the audio output stage. Otherwise, the fault lies in the audio stage itself. Thus, by injecting the signal, the fault can be traced. To check the ·RF stage, an audio signal can be injected in the RF stage. If the output appears at the speaker, the equipment is working properly, other- wise the fault lies in the RF stage. The Signal Injector Circuit besides injecting signals at RF, IF and AF stages can also detect signals at these frequencies. 1 X 1 is a 3V output transformer
used in pocket transistor sets.