I have a bit of experience with this kind of stuff and my buddy does=20 underground utilities location professionally (its his day job). 1) A couple of people have suggested using divining rods. Seriously,=20 its worth a try. My buddy Russell (the guy who does this=20 professionally) uses divining rods whenever he has to locate old=20 sewer pipes that he can't connect his electronic tracing gear to. He=20 says that it works well for him. Me: I can't offer an opinion. I haven't observed divining in=20 operation nor have I tried doing it myself. But I absolutely won't=20 discount its effectiveness. 2) The easy way to do this electronically is to attach a relatively=20 high voltage 1KHz signal to one end of the wire. Grab any old audio=20 power amplifier that can deliver at least 20 or 30 Vac (rms), ensure=20 that the ground end of that signal is actually grounded (near the=20 line if possible), and connect one conductor of that line to the=20 output of the amplifier. Then use an equivalent of a "Hound"=20 telephone line tracer. If you have one, use it. Otherwise, just use=20 an audio preamplifier that can handle low-level mic signals. Attach=20 a length of unshielded wire to the preamp's input and make sure that=20 you can hear the 1KHz tone from more than a foot away. If you have an old PA amplifier with a 70V speaker output, use that=20 to drive the line. I've got an old piece of Telco CO equipment called a "Jumper Tracer"=20 - its used for tracing long jumper wires in an old-fashioned Telco=20 Central Office. That's where all of the incoming subscriber wires=20 wind up on large walls of dense punch-blocks and need to be=20 cross-connected to the switch equipment. It uses a fairly-low=20 frequency RF carrier modulated at 800Hz or so. The pickup wand has a=20 coil wound on a short piece of ferrite rod at its end - this coil=20 connects to the pickup unit with a piece of shielded twisted-pair audio cab= le. This unit is absolutely marvellous - I can trace wires that are=20 inside conduit buried under six or eight inches of concrete. But if=20 your wires are not inside metal pipe, its really easy to detect an=20 audio-frequency electric field using that power amp mentioned above=20 and a Hound listen unit. Finally, my company makes a couple of pieces of equipment used for=20 detecting coating damage on buried pipelines. The transmitter sends=20 audio-frequency current down the pipeline and the detector is a=20 hand-held large-diameter walking stick that connects to the backpack=20 that the survey guy is wearing. The pickup elements (there are 5)=20 are circular coils that feed high gain, very low noise preamps. When=20 all is said and done, we wind up with the depth of the pipeline (if=20 it is buried or under water) and the magnitude of the current at that=20 location. All of that data is logged along with the GPS=20 coordinates. All the guy has to do is walk along the pipeline's=20 path, swinging that thick walking stick from side to side. Every=20 time the stick is exactly in line with the pipeline, he gets a beep=20 from the receiver and the current measurements are made. The beeps=20 help keep him on track when he doesn't know exactly where the line is=20 buried or if he is in a boat. This gear is good for taking measurements several miles away from the=20 transmitter. But its WAY overkill for what you need to do. dwayne At 10:57 PM 5/14/2013, Bob Blick wrote: >When the power company wants to follow the path of a buried cable, they >attach a gadget to one end and walk along the ground with another >gadget. Looks real easy when you have that $7000 pair of gadgets. > >Any idea what inexpensive thing I could modify to get a similar effect? >I don't need to do it on a live wire, and the maximum depth underground >is one meter or less. > >Thanks, >Bob > >-- >http://www.fastmail.fm - Send your email first class > >-- >http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive >View/change your membership options at >http://mailman.mit.edu/mailman/listinfo/piclist --=20 Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax www.trinity-electronics.com Custom Electronics Design and Manufacturing --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .