On 4/26/2015 9:08 AM, Leif Neland wrote:
Leif Neland formulerede spørgsmålet:
The perimeter loop cable around my lawn for my automower is broken.
I have a cable fault detector with a tone generator and a "pen"
receiver, which can trace along the cable, but it doesn't work when
the single wire goes under ground or concrete.
I wonder if a network/telephone cable tester can work on a single wire
underground.
I'm looking at
http://www.ebay.co.uk/itm/Portable-N...r/181692076054
After all, a single wire in the ground should look a little like a
coaxial cable?
Just for the record: It does not work.
But apperently, the manual says it only shows if a coax or phone cable
is open or shorted, not the length, so it couldn't find the length of bu
broken underground wire.
On the other hand, it does work as specified: It has shown a fault in a
ethernet cable.
Leif
What you need is an underground pipe locator.
Don't know how technically inclined you are or how much effort
you want to put into this.
I did a bunch of experiments of this nature.
I used a function generator into the secondary of a 12VAC wall wart
and took the 150ish volts off the primary. Also built an oscillator
with a 555.
Hook one end to the wire and the other into a ground rod.
Don't forget to disconnect whatever electronics you have hooked
to the wire so you don't bust it.
To sense the field, I used a big coil of wire wound on a chunk
of iron.
Plugged that into the microphone input of a Dell Axim X51 PDA.
Use a spectrum analyzer program to distinguish the signal from
the noise. I like Pocket Instrument best.
5.5KHz. worked best for this setup.
Works better than I expected on shallow wires.
The concept should work with any device with a microphone
input and a spectrum analyzer program. There are dozens of
them for android. Suggest you put a pair of diodes across
the coil so you don't bust your phone from a transient.
If the wire is not insulated, you can sometimes stuff currrent
into it and probe the ground along the wire path to find
out where it stops.