Cable Tracer
100MHz FM

Cable Tracer kit is available from
Talking Electronics for $10.00 plus $6.50 postage. 
Click HERE  to buy kit.



This project detects cables when the mains is not present.
It is mainly used to detect cables that cannot be located during the "fit-off" stage.
Sometimes the plasterer will forget to pull a cable through and it will be "lost" behind the plaster.
That's why you need a wiring diagram. It will confirm the location of the cable.
However, if a cable is hidden behind a wall or in the ceiling of a double-storey building, this project will assist in detecting its location.
Clip the antenna lead to any of the conductors of the cable you are tracing and use an FM radio with the antenna extended to locate the cable.
This will work to about 3 metres. 

The RF oscillator between pins 5 and 6 works at about 1 MHz and the FM radio used to pick up the signal as a harmonic.
The signal is interrupted by the low-frequency oscillator between pins 1 and 2 that produces a  beep, different from any other background noise.

All the parts fit neatly on the PC board.
The IC fits into a socket with the cut-out shown on the overlay.

The most crucial item to connect is the battery snap. The "cup" on a 9v battery is the negative, but we are making a RECEIVING snap, and the "cup" is the positive. You must look at the diagram to see how this is connected.
Note: the negative connection to the battery is at the top.
When connecting the battery, make sure the switch is OFF and connect one terminal at a time.  


Cable Tracer - 100MHz
$10.00 plus $6.50 postage. 
 HERE to buy kit

1 - 470R  Use 1k with LED in kit
1 - 3k9
1 - 22k

1  -  100p ceramic
1  -  22n ceramic
1  -  2u2 electrolytic
1  -  10u electrolytic

1  -  1N 4148 diode
1  -  3mm red LED
1  -  battery snap
1  -  47c14  IC
1  -  14 pin IC socket

1  -  mini slide switch
1  -  10cm tinned copper wire for battery snap
1  -  30cm wire for antenna
1  -  black alligator clip
1  -  20cm fine solder

1 - Cable Tracer  PC Board

Not in kit:   1  -  9v battery