Basic Theory information: The LC phones are used with two people testing, verifying and identifying individual wires in multi-conductor cables or where the two ends of the cable may be in different buildings or areas. Imagine a picture of two kids talking to each other through soup cans and a string in between them. These LC phone are those soup cans and they really work.
The method for making these LC phones is achievable as soon as you find the phones (finding the phones are the hardest part).
a)Rewire the phones to a wire connection drawing.
b)On one phone install a switch and a 9 volt battery
c)On both phones install test leads according to the drawing.
d)Once the leads of both phones are touching, communications between both phones become possible.
An example of how this is used: Two guys were installing speakers and speaker wires in the walls for their home theater system. The speaker wires were installed at four speaker locations and all were not identified prior to pulling them all to the amplifier. There are (4) 2-wire cables at the amplifier and you don’t know which is the front right, front left, the rear right or the rear left wires. One of the LC phones will clip on to the two wires at the left rear location while the other phone will be connecting to each set of wires one at a time until they are able to communicate. At this point they tell each other what wire they have found and mark the wire for its location.
CAUTION: Do not use this device on energized wires of any voltage, electric shock or death could result.