Can a probe and tone generator trace cables behind a drywall?

John-

I don't see any responses to your question. I was hoping to see if there was some easy way to do what you ask. Another similar approach might be to generate an RF signal with some kind of "buzz" modulation, that could be picked up by a portable radio. Maybe some kind of spark-coil vibrator would put out a broad spectrum that could be picked up on any frequency at the low end of the standard AM broadcast band.

I believe I have heard of some kind of equipment that does what you want, used by electricians. You might ask about it in the electrical department of one of the builder supply stores or stores such as Lowes or Home Depot.

Fred

I didn't see any replies either, so I just checked it. My conclusion is that if the cable is touching the drywall on the other side from you, you'll hear it fine. If, however, it's the full 3.5" away that it might be (assuming a 2x4 behind the drywall), tracing it will be a much more questionable proposition.

here is one:

First off, you should've asked thie on the more appropriate comp.dcom.cabling newsgroup.

Cat5 cabling is so tightly twisted that if you connect the toner to a single pair, you'll get nothing when the probe is right next to it. So you have to connect one wire of the toner to one pair or one wire of one pair, and the other wire of the toner to another pair or wire of another pair. Try it and you'll see what I mean.

I have one probe that has a volume control and can be turned up, so it will make enough noise to detect fairly far away - some probes don't have a volume control. But it depends on what's around the cabling, how new the battery in the toner is, etc. The toner will operate on a battery that's down to just a few volts, so check it occasionally with a DMM and replace it when it's below 7.5V.

This is true not the same pair. I have the older version of Fox and Hound by Triplett (got it at a garage sale for a couple bucks):

The leads to be traced can't be grounded or connected. I have been able to trace Cat-5 cables by just waving the probe within a couple of feet of cables on the surface. I also found the position of 2 cables that I fished into a lathe and plaster wall from another floor (not in conduit). Drilled a 1/4 inch hole and fished them out with a hooked wire. Nice and neat.

Richard

in message news:...

Or connect one end of the tone generator to one wire of the twisted pair, and run the other end of the generator to another jack in the house (connecting to the same wire on the cable) via an external wire (which would have to be spaced sufficiently from the wall to keep from distorting your response). In this case, if the length of cable you are tracking is included in your circuit, then you should get a good strong response(?). Just an idea.

Sam B.

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You must have thick plastering for the lathe not to show up poking out of the wall! ;)

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Mike Brown: mjb[at]pootle.demon.co.uk | http://www.pootle.demon.co.uk/

Was it a wood lathe or a metal lathe?

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Made out of wood; that is wht it was so hard to find..

The lathe or the lath?

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Jeez I didn't know this was a spelling test. Well I actually do have a metal lathe. It's only 8 " between centers and it would fit into a lath and plaster wall. Sorry for the misspelling my spell checker doesn't check context. It does seem to be a common missuse:

More on the subject l just used my kids metal detector to trace a live bx in a ceiling to determine that it just ended in the middle of nowhere (bare wires with old tape). So I was able to eliminate it and terminate the the wiring in the box.

You are going to *kill* the wire?? In a *box*?

G R O S S !