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

Discussion in 'General Electronics' started by John Smith, Aug 11, 2004.

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  1. John Smith

    John Smith Guest

    Can they be used to trace cat 5 cables behind drywalls?
  2. 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.
  3. Ryan Wheeler

    Ryan Wheeler Guest

    here is one:
  4. 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.
  5. Richard

    Richard Guest

    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.

  6. Sam B.

    Sam B. Guest

    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.
  7. Mike

    Mike Guest

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

    CJT Guest

    Was it a wood lathe or a metal lathe?
  9. Robert Baer

    Robert Baer Guest

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

    CJT Guest

    The lathe or the lath?
  11. Richard

    Richard Guest

    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.
  12. Robert Baer

    Robert Baer Guest

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

    G R O S S !
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