Electronic projects

you are here: home page :: projects :: Tools & measurement :: testing equipment :: Signal Tracer and Injector

Signal Tracer and Injector

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.

Circuit diagram

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.
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.

author: Andy Collinson
e-mail: anc@mitedu.freeserve.co.uk
web site: http://www.zen22142.zen.co.uk
project categories:
folder Audio (49)
folder Power & high voltage (43)
folder Radio (23)
folder Light & LED (31)
folder Tools & measurement (40)
folder Telephone (18)
folder Automotive (10)
folder Microcontrollers (12)
folder Sensors & control (47)
folder Timers & oscillators (40)
folder Miscellaneous (26)

StumbleUpon button

Share this page
Bookmark and Share
project subcategories:
All subcategories
testing equipment
measuring devices
other tools

similar projects:
Beeper to find short circuits
Connection Tester
Continuity Tester
Crystal Tester
IR Remote Control Tester
IR Remote Control Tester
Latching Continuity Tester
Live-line Detector
Logic Probe

recently added projects:
Doorbell for the Deaf
High Quality Intercom
Combinational Conjuring Trick
Ultrasonic Dog Whistle
Quiz Circuit
LED Torch
Insect Repellant
Speaker Microphone Circuit
Magic Wand Conjuring Trick.

most popular projects:
Led display digital Voltmeter
500W low cost 12V to 220V inverter
Low pass filter - Subwoofer
Metal Detector
High And Low Voltage Cut Off With Time Delay
Basic UPS Power Supply
2N3055 Power Amplifier
200W audio amplifier
LED Torch
100W RMS Amplifier

DIY Electronics Projects

Promote Your Page Too