Looking for help trouble shooting an invisible fence

Discussion in 'General Electronics Chat' started by gte, Jun 8, 2011.

  1. gte

    Thread Starter Active Member

    Sep 18, 2009
    347
    4
    I'm looking for help troubleshooting an invisible underground wired dog fence, by Pet Safe.

    The wire loop has 13Ω of resistance, it's about 1200 or 1300 feet of 20 gauge solid core copper wire, and calculations say I should have about 11 or 12Ω of resistance, so based on that I believe it is good and does not have a break either.

    I'm having to put the signal generator unit on the highest setting (rated for 2400 to 5000 feet) to get it to work and it will only work when the collar is within a single foot of the wire, which is useless. This is not how it worked originally so I'm thinking something is hosed. I believe the unit puts out a radio frequency, but I'm not sure the frequency or how to test the strength. I'd like to test the strength coming right out of the unit with some sort of meter if that is possible, any ideas?
     
  2. mbohuntr

    Active Member

    Apr 6, 2009
    413
    32
    I have looked at oscillator outputs on a scope.Don't know about this situation. Put a cap in series so the output isn't attenuated. It won't help with the frequency, but you should be able to see the signal and it's amplitude. Turn the gain down first as a precaution in case I'm giving you bed advice...Just a thought.
     
    gte likes this.
  3. CD-RW

    Member

    Feb 26, 2011
    33
    1
    Might not be the wire underground?

    Have you checked the sig gen strength first?

    Do you have more details of how this is suppoesd to work please?

    I take it it is some sort of antenna that puts out a signal that is detected by a receiver on the dogs collar, that then produces some sort of warning (like HF noise) that makes the dog stay inside the antenna area?
     
    gte likes this.
  4. gte

    Thread Starter Active Member

    Sep 18, 2009
    347
    4
    Thanks for the reply, any idea what size cap? Won't the cap just let the signal pass right through it?


     
  5. gte

    Thread Starter Active Member

    Sep 18, 2009
    347
    4
    Hi,

    It is supposed to transmit an r/f signal around in a loop, which when the wires are wrapped together the magnetic field is canceled. The collar can vibrate and/or shock the dog, depending on the setting and the collar can tell if you are within 2 different zones of the loop wire. The warning (audible beep) zone and the shock/vibrate zone.

    I don't know the frequency, but there must be a way to check the signal strength of the r/f frequency? Is there an Oscope type of device for radio frequency detection?




     
  6. mbxs3

    Active Member

    Oct 14, 2009
    141
    3
    Is it possible the battery in the dog collar is weak? When was the last time it was replaced?
     
  7. mbohuntr

    Active Member

    Apr 6, 2009
    413
    32
    Whoops... I decided to make sure I got my stuff straight before I continued, and look at the manual I used. I apparently used it to isolate the signal generator from the circuit, not the scope. The scope should see the signal without the cap...:rolleyes:

    http://www.tequipment.net/pdf/elenco/am-550tk.pdf
     
  8. gte

    Thread Starter Active Member

    Sep 18, 2009
    347
    4
    No it is new, good thought though

     
  9. gte

    Thread Starter Active Member

    Sep 18, 2009
    347
    4
    I will try and put the scope on it, I'm just hoping the voltage values aren't a problem, it should be AC, correct? I'm hoping I can measure them with my DMM first to make sure I don't risk any damage to my scope.




     
  10. gte

    Thread Starter Active Member

    Sep 18, 2009
    347
    4
    After speaking to PetSafe today, they told me the device generates a frequency at 10.65kHz.

    Does anyone have any recommendations for a frequency/signal strength meter that can operate around 10.65kHz and is less than $50 or $100 dollars?
     
  11. mbohuntr

    Active Member

    Apr 6, 2009
    413
    32
    You could..... buy a spare collar and try it w/your fence. If it doesn't work, you can be pretty sure it's the transmitter and return the collar. :D
     
  12. loosewire

    AAC Fanatic!

    Apr 25, 2008
    1,584
    435
    Take mbohuntr bed advise,thanks for a shot at general chat.
    Don't touch the Loosewire.
     
  13. mbohuntr

    Active Member

    Apr 6, 2009
    413
    32
    "Bed advice." Loosie???? Are you tired?? There are only two parts to the fence, the transmitter, and receiver. Since all petsafe fence systems operate on the same frequency, and you find out the collar is shot, problem solved. Either try to fix the collar, or keep and use the spare. If the transmitter is shot, either buy a new system, or try to repair the one you have.
    Seems like the easiest and quickest route. ;)
     
  14. gerty

    AAC Fanatic!

    Aug 30, 2007
    1,153
    304
    I would disconnect the fence transmitter from the buried loop of wire, make a test loop from approx 10' of loose wire (no pun) and see if the buried loop is the culprit.
     
  15. mbohuntr

    Active Member

    Apr 6, 2009
    413
    32
    That's a really good suggestion! I assumed that the wire was fine given the OP's resistance measurements. Could the insulation be damaged ?


    Now that' s punny!!! :D
     
  16. gerty

    AAC Fanatic!

    Aug 30, 2007
    1,153
    304
    If I'm not mistaken the wire itself must be insulated from ground, but what do I know?
    I've made a robotic interface with a similliar type of electric fence. To test it we put a loop like I mentioned and it worked.
     
  17. mbohuntr

    Active Member

    Apr 6, 2009
    413
    32
    A lot more than I do..
     
  18. gte

    Thread Starter Active Member

    Sep 18, 2009
    347
    4
    Thanks for the replies everyone. I have tried the short loop.

    The thing is this, the company says there can be interference from many different things and I would like to have a measurement device that I can compare to and maybe even make a baseline with a large loop of wire.

    With the 10' loop, the wire is too close and it ends up canceling out the signal unless the collar is less than 1 foot from the wire itself.

    At this point, I want to make a 50' loop out in the backyard where there is not any wire or other forms of interference and measure signal strength ... then compare it to the in ground wire in different locations. Thoughts?
     
Loading...