Circuit Tracer

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rubenste...@googlemail.com

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Nov 15, 2008, 7:13:29 AM11/15/08
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I've seen the BT chaps using a pice of test equipment that injects a
signal down a wire which they can then track as an acoustic beep to
find breaks etc. I think also they can track the signal without the
need to connect directly to the wire.

Google searches make me think this equipement might be know as a
circuit trace. I've also come across things called fuse finders,
which I don't think are the same thing.

I'd appreciate a bit of clarification and to know if there are any
affordable diy equivalents on the market.

Many thanks

Martin

Peter Parry

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Nov 15, 2008, 8:47:59 AM11/15/08
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On Sat, 15 Nov 2008 04:13:29 -0800 (PST),
rubenste...@googlemail.com wrote:

>I've seen the BT chaps using a pice of test equipment that injects a
>signal down a wire which they can then track as an acoustic beep to
>find breaks etc. I think also they can track the signal without the
>need to connect directly to the wire.

Usually called a Tone and Trace Kit. They are mainly used for
identifying a single pair in a bundle of cables where the two points
are some considerable distance away from each other (up to a mile or
so). They are not widely used in electrical wiring as the need to
trace a single cable isn't common and it can be done just as easily
using a multimeter if the ends are not 100's of yards apart.

>Google searches make me think this equipement might be know as a
>circuit trace. I've also come across things called fuse finders,
>which I don't think are the same thing.

Fuse finders are much the same but optimised for mains cabling and
used on live circuits. You inject a tone into a wire by plugging the
transmitter into a socket and it allows you to detect where in a
distribution board it is going. More use on radial circuits and
industrial installations with lots of wires going to different places.
Quite limited use in domestic installations.

>I'd appreciate a bit of clarification and to know if there are any
>affordable diy equivalents on the market.

Maplin do a telephone circuit one for £30, item code N74CC. You could
not use this on live mains circuits.

Neither type will tell you if a cable has one conductor of a pair
damaged. When used to trace breaks the tone detector must be held
close to the cable as you move along it so not much use for mains
wiring in a wall or under floorboards. To determine where breaks in
wires are you need a Time Domain Reflectometer, the cheapest of these
I've seen is about £250
http://www.computerware.co.uk/FaultCasterproduct.htm

Dave Plowman (News)

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Nov 15, 2008, 9:12:21 AM11/15/08
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In article
<449d827a-00d3-44ad...@w24g2000prd.googlegroups.com>,

Check out Ebay. I bought one for not a lot - IIRC under 30 quid. No brand
name but works well. Look for Cable Tracker. Consists of a sender and
receiver. Can be used just to check continuity or will send an RF signal
down the cable which can be picked up using the tracer. Works well through
floorboards, etc.

It comes with a telephone line checker - but by the plug supplied is
designed really for US ones. I've not investigated this side of it.

--
*Be nice to your kids. They'll choose your nursing home.

Dave Plowman da...@davenoise.co.uk London SW
To e-mail, change noise into sound.

tony sayer

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Nov 15, 2008, 9:03:27 AM11/15/08
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In article <449d827a-00d3-44ad...@w24g2000prd.googlegroup
s.com>, rubenste...@googlemail.com scribeth thus

Look up tone and trace on Maplins website they do one of these I bought
on from there a while ago there is a tone generator and a stick like
thing with a pointed probe on which traces the distinctive two tone
signal...

their website is U/S at the moment otherwise I'd give U the URL...
--
Tony Sayer


meow...@care2.com

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Nov 15, 2008, 1:26:11 PM11/15/08
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a capacitor meter does that just fine


NT

meow...@care2.com

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Nov 15, 2008, 1:27:59 PM11/15/08
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Its just an oscillator with output bugger - typo! buffer I mean, plus
capacitor to isolate mains and diodes. The detector can be a CMOS
linear amp with a detector plate. Simple stuff if you can build basic
electronics.


NT

rubenste...@googlemail.com

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Nov 15, 2008, 4:19:03 PM11/15/08
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Sincere thanks to everyone for such helpful and kind replies. I
really appreciate your taking the time to pass on your knowledge.


Martin

Dave Plowman (News)

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Nov 15, 2008, 6:32:03 PM11/15/08
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In article <i9jth4dabfb8d6vku...@4ax.com>,

Peter Parry <pe...@wpp.ltd.uk> wrote:
> >I've seen the BT chaps using a pice of test equipment that injects a
> >signal down a wire which they can then track as an acoustic beep to
> >find breaks etc. I think also they can track the signal without the
> >need to connect directly to the wire.

> Usually called a Tone and Trace Kit. They are mainly used for
> identifying a single pair in a bundle of cables where the two points
> are some considerable distance away from each other (up to a mile or
> so). They are not widely used in electrical wiring as the need to
> trace a single cable isn't common and it can be done just as easily
> using a multimeter if the ends are not 100's of yards apart.

It can be handy to identify one cable out of several if, say, you wish to
break into it and can't trace it mechanically. As I did recently when
adding a light - there were five likely candidates, all 1.5mm TW&E running
along under the floor.

--
*Who is this General Failure chap anyway - and why is he reading my HD? *

James Salisbury

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Nov 16, 2008, 6:19:22 AM11/16/08
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Dave Plowman (News) wrote:
> In article <i9jth4dabfb8d6vku...@4ax.com>,
> Peter Parry <pe...@wpp.ltd.uk> wrote:
>>> I've seen the BT chaps using a pice of test equipment that injects a
>>> signal down a wire which they can then track as an acoustic beep to
>>> find breaks etc. I think also they can track the signal without the
>>> need to connect directly to the wire.
>
>> Usually called a Tone and Trace Kit. They are mainly used for
>> identifying a single pair in a bundle of cables where the two points
>> are some considerable distance away from each other (up to a mile or
>> so). They are not widely used in electrical wiring as the need to
>> trace a single cable isn't common and it can be done just as easily
>> using a multimeter if the ends are not 100's of yards apart.
>
> It can be handy to identify one cable out of several if, say, you wish to
> break into it and can't trace it mechanically. As I did recently when
> adding a light - there were five likely candidates, all 1.5mm TW&E running
> along under the floor.
>
An MK live wire detector can also be used for cable identification, keep
pulling the fuses till the light goes out...

Dave Plowman (News)

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Nov 16, 2008, 7:29:50 AM11/16/08
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In article <aOednbbtB8MmnL3U...@pipex.net>,

James Salisbury <nntp.dsl.pipex.com> wrote:
> > It can be handy to identify one cable out of several if, say, you wish
> > to break into it and can't trace it mechanically. As I did recently
> > when adding a light - there were five likely candidates, all 1.5mm
> > TW&E running along under the floor.
> >

> An MK live wire detector can also be used for cable identification, keep
> pulling the fuses till the light goes out...

Because they were bunched at one point this didn't actually give an
accurate indication. But removing the line from the appropriate MCB and
clipping on the transmitter wire gave instant and definite identification.
But I don't have an MK device so was using another make.

--
*The most common name in the world is Mohammed *

Andrew Gabriel

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Nov 16, 2008, 9:04:56 AM11/16/08
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In article <4ffea61...@davenoise.co.uk>,

"Dave Plowman (News)" <da...@davenoise.co.uk> writes:
> Check out Ebay. I bought one for not a lot - IIRC under 30 quid. No brand
> name but works well. Look for Cable Tracker. Consists of a sender and
> receiver. Can be used just to check continuity or will send an RF signal
> down the cable which can be picked up using the tracer. Works well through
> floorboards, etc.
>
> It comes with a telephone line checker - but by the plug supplied is
> designed really for US ones. I've not investigated this side of it.

I got a PTS-100/200 for £10 from a computer fair over 10 years
ago. It looked brand new, but both batteries were dead. Extremely
useful when I was doing some telephone and later cat 5e cabling.
I have occationally used it with mains wiring too. Must admit, I
haven't seen it that cheap since. That exact model still exists;
seems to be around £50 now (was typically £80 when I bought it).
Comes with a standard BT phone plug for checking polarity, although
the only things I ever found which cared were the early callerID
devices (first CD50's and first Hayes modems which supported BT
callerID). I still make a point of getting the polarity right
though.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

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