Did you not read the manual - (page 8. Use of mouse on drain rods)

There is also much general wisdom in the manual about the subject.

The CAT and Genny system is a highly sophisticated radiolocation system, used by utilities and groundworks contractors.

It would not be economic to construct anything as good for a single search operation.

go well

 

Conclusion: It worked! What more can I say? At the workbench, the transmitter could be detected at least about 10 feet away. Detection distance increased with antenna length. In the field with the buried perimeter wire, the signal was easily detected a foot or two above the ground, by sweeping the receiver back and forth perpendicularly to the wire. I found and repaired the break in minutes.

I am trying to replicate your results, but when I ordered a breadboard the circuit, it came with the following "power supply".

http://www.petervis.com/Raspberry_PI/Breadboard_Power_Supply/YwRobot_Breadboard_Power_Supply.html

I have tried modifying your design to only use this YwRobot power supply, two crystal oscillators, and two capacitors (inline with the input audio signal). The capacitors are 100 μF each (instead of your 274 μF ones) because that's all I had laying around. I am encountering a couple of problems, namely

1. It seems that as soon as I connect both left and right channel to its corresponding capacitor, then the 1000MHz signal goes away. Either left or right connected transmits fine, but I cannot get them to both transmit simultaneously.
2. Because I have about 600 feet of underground wire, the resulting antenna are long enough to be received by my AM radio even as I step away from where the wire is laid.

I would appreciate any advise you could provide regarding a modified circuit as well as this antenna length problem.

Thanks in advance,

Troy

 

I'm trying to build this circuit- and since I don't have parts on hand I need to order anything. Do you have more details on exactly what capacitor you used for the coupling capacitors?

thanks!
Andy

 

Still there Andy? Apologies to you and Troy (who I assume is long gone). I don't get notified when someone posts here if they don't quote or tag me. And I'm not in the habit of looking at my old threads.

Those big green coupling capacitors were most likely pulled from an old CRT monitor I stripped. I used to do that for parts and fun but I've since decided it's not all that fun, and I am unlikely to need the parts.

Anyway, they were rated for high voltage which is not needed for this project. So they are much larger physically than necessary. I also recall trying various values and it's not very critical. A 0.1µF would work, but the coupling would be slightly reduced. I think I tried a 0.47µF with similar results.

Note that Troy read my schematic as showing 274µF. Easy mistake. I used the the capacitor code often seen on smaller caps that uses 2 significant figures followed by the number of zeroes, with the value in picofarads. So a 274 is 270000pF or 0.27µF.

Let me know if you have trouble finding the oscillator. I did, and I may have a note where I got them.

 

Thanks for getting back to me! I already constructed your circuit. I used an oscillator from digikey, P/N MXO45-3C-1M0000. Instead of using a tone generator, I just plugged in two different audio sources, each playing wildly different Pandora stations. Unfortunately the AM radio I was using must be too good, as I can pick up a signal from many feet away in some places, which makes it really difficult to pinpoint exactly where the problem is. Also, the oscillators must not have exactly the same frequency as I can fiddle with the AM dial (analog tuner) on the radio and control which of the two AM stations it picks up.

I haven't decided what my next step is going to be, either try and dial down the signal strength of each transmitter, or else simply start jumpering parts of the fence with really long wires and just trial-and error to find the break location.

Andy

Still there Andy? Apologies to you and Troy (who I assume is long gone). I don't get notified when someone posts here if they don't quote or tag me. And I'm not in the habit of looking at my old threads.

Those big green coupling capacitors were most likely pulled from an old CRT monitor I stripped. I used to do that for parts and fun but I've since decided it's not all that fun, and I am unlikely to need the parts.

Anyway, they were rated for high voltage which is not needed for this project. So they are much larger physically than necessary. I also recall trying various values and it's not very critical. A 0.1µF would work, but the coupling would be slightly reduced. I think I tried a 0.47µF with similar results.

Note that Troy read my schematic as showing 274µF. Easy mistake. I used the the capacitor code often seen on smaller caps that uses 2 significant figures followed by the number of zeroes, with the value in picofarads. So a 274 is 270000pF or 0.27µF.

Let me know if you have trouble finding the oscillator. I did, and I may have a note where I got them.

 

Too much power shouldn't be a problem, just turn down the voltage of the transmitter. I'm glad you at least have something to work with.

 

worked for me

 

Hallo

I am thinkng about using this circuit to trace some hard to find pp pipes buried outdoor in soil, bricks or concrete. These pipes are sealed at the far end. The pipes are at least an inch wide, and I can push another smaller pipe down them with some wires in, using it as a probe (I used this method to drive a buzzer attached at the head of the probe, whith which I succeded with some simpler pipes). The pipes lenghts are various, about from 20 to 200 feet (5-50 meters).

I wonder if I'd better mount the oscillator at the near end of the probe and use the entire length of wire(s) as the antenna, or if I would better mount the oscillator at the far end of the probe, with a smaller length of wire for the antenna twisted or folded in the probe head.

Thank you.
Luigi

 

I wonder if I'd better mount the oscillator at the near end of the probe and use the entire length of wire(s) as the antenna, or if I would better mount the oscillator at the far end of the probe, with a smaller length of wire for the antenna twisted or folded in the probe head.

Hard to say. I think I'd start with a short length of antenna, maybe a foot or two. It may be harder to detect this segment than the dog-fence wire approach, but it should be far easier to map out where the signal is and is not. No way to know except to experiment. You'll have trouble either way if your soil, bricks or concrete are too thick.