SteveB wrote:
My electrician friend came last weekend to do some work. He had this device
that looked like a large black crayon with a green conical end. About six
inches long, and as big around as a quarter.

He would put it close to a wire or a socket, and if it was hot, the green
light would come on, and a beep.

He said he thought they made them for 12v. automotive use. Anyone seen or
used these 12v. models?

Steve


Something like that works off of radiated emissions from the line, which
requires AC. It may work in a car if the engine is running, but don't
expect it to work with just a battery and no motors or noisy electronics
on the line.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html

My electrician friend came last weekend to do some work. He had this device
that looked like a large black crayon with a green conical end. About six
inches long, and as big around as a quarter.

He would put it close to a wire or a socket, and if it was hot, the green
light would come on, and a beep.

He said he thought they made them for 12v. automotive use. Anyone seen or
used these 12v. models?

Steve

On Tue, 25 Mar 2008 10:55:49 -0700, Tim Wescott
wrote:

SteveB wrote:
My electrician friend came last weekend to do some work. He had this device
that looked like a large black crayon with a green conical end. About six
inches long, and as big around as a quarter.

He would put it close to a wire or a socket, and if it was hot, the green
light would come on, and a beep.

He said he thought they made them for 12v. automotive use. Anyone seen or
used these 12v. models?

Steve


Something like that works off of radiated emissions from the line, which
requires AC. It may work in a car if the engine is running, but don't
expect it to work with just a battery and no motors or noisy electronics
on the line.

Indeed. I use them all the time, and they DONT work on DC

Gunner

"Gunner" wrote: Indeed. I use them all the time, and they DONT work on DC
^^^^^^^^^^^^^^^^^^^
I have been using those for years. It's one of the handiest tools you can
put in
your shirt pocket. But, around the car, no. You need about 60 volts AC to
trigger it. However, you can buy a gizmo that clips onto the wiring in a
car, which injects pulses. You can then trace those pules around the car
using a hand-held receiver.

Incidentally, the little AC probe the OP is talking about can mislead you.
If the break is in the common side of the circuit, it will indicate you have
power. Say your pistol drill won't run, and the "chirper" says it should.
Don't immediately start pulling the drill apart.

Gunner wrote:

Indeed. I use them all the time, and they DONT work on DC

Gunner



They make some that do, but they are two seperate pieces. One
generates noise on the wire, and the other tracks it. It is sold for
telco, security system, and network troubleshooting.

Ask on news:comp.dcom.cabling


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Robert Swinney wrote:
(top posting fixed)
"Tim Wescott" wrote in message
...
SteveB wrote:
My electrician friend came last weekend to do some work. He had this device
that looked like a large black crayon with a green conical end. About six
inches long, and as big around as a quarter.

He would put it close to a wire or a socket, and if it was hot, the green
light would come on, and a beep.

He said he thought they made them for 12v. automotive use. Anyone seen or
used these 12v. models?

Steve


Something like that works off of radiated emissions from the line, which
requires AC. It may work in a car if the engine is running, but don't
expect it to work with just a battery

Tim Sez: " . . .and no motors or noisy electronics
on the line. . . ."

How's about leaning on the horn while the tech has it up to his ear ?

Bob (don't know AC from DC) Swinney

I meant electrically noisy. An old-style vibrator horn would dump
plenty of electrical noise on the wire, but somehow I dunno if things
would work, even so...

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html

Michael A. Terrell wrote:
Gunner wrote:
Indeed. I use them all the time, and they DONT work on DC

Gunner



They make some that do, but they are two seperate pieces. One
generates noise on the wire, and the other tracks it. It is sold for
telco, security system, and network troubleshooting.

Ask on news:comp.dcom.cabling

They were called "fox and hound" when I was engineering telco stuff.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html

Tim Wescott wrote:

Michael A. Terrell wrote:
Gunner wrote:
Indeed. I use them all the time, and they DONT work on DC

Gunner



They make some that do, but they are two seperate pieces. One
generates noise on the wire, and the other tracks it. It is sold for
telco, security system, and network troubleshooting.

Ask on news:comp.dcom.cabling

They were called "fox and hound" when I was engineering telco stuff.


I couldn't remember the name. I used an RF generator on CH 3 and a
Sadelco TV FSM the few times I needed one. I had a really bad habit of
numbering both ends of every com cable. It ticked of a lot of other
people, till something went down and they could yell numbers at each
other.


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"Howard Eisenhauer" wrote: Actually it would be possible to build one that
detects DC using a
hall sensor, (clip)
^^^^^^^^^^^^^^^^^^^^^
That would work, but it wouldn't be the same as the voltage detector that
chirps when placed next to a live AC wire. Hall effect detects current
flow, not voltage.

On Tue, 25 Mar 2008 16:10:05 -0400, "Michael A. Terrell"
wrote:


Gunner wrote:

Indeed. I use them all the time, and they DONT work on DC

Gunner



They make some that do, but they are two seperate pieces. One
generates noise on the wire, and the other tracks it. It is sold for
telco, security system, and network troubleshooting.

Ask on news:comp.dcom.cabling

Correct. I have a couple sets of the old Progressive Electronics line
chasers for DC or cold wire work

Gunner