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inductor fence charger question, please

Discussion in 'Electronic Basics' started by HC, May 9, 2007.

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  1. HC

    HC Guest

    Hey, all, I have about 4 of my 5 acres fenced to contain my dogs (I
    have to keep them fenced since someone, I don't know for sure who,
    around here shoots dogs). I have fenced most of my 5 acres so they're
    not just in some little pen but they kept digging out. To deter that
    I have installed an electric fence around the perimeter, a few inches
    above the ground and about 6 inches in from the pen so they cannot dig
    under the fence without hitting it. Unfortunately, it's a low-powered
    fence charger and grass and weeds grow into it and seem to short it
    out, nullifying it's effectiveness and the dogs have been able to dig
    out in a few places. I would like to use a more powerful fence
    charger and it occurred to me to try to build something homemade
    instead of just throwing money at a more expensive/powerful charger.

    Back in an electronics class I took in college we used a 12 volt power
    supply and a small inductor in a simple circuit that passed current
    through the inductor, through a load of some kind and then, when we
    broke the power supply to the circuit, the inductor would cause a
    spike back through a different portion of the circuit and would light
    a small bulb (I don't know what they are called; they have gas of some
    kind in them (not LEDs), with two sticks for electrodes, no
    filament). The thing would flash that light very briefly but very
    brightly, something that the original 12 volts could not do on its
    own. The idea they were trying to point out was how an
    electromagnetic field could form around a conductor when electrons
    (current) passed through it and how much it could amplify the voltage
    when that field collapsed.

    So, I'm wondering, could I use a similar circuit (how do I build
    that? It's been 15 years since I took that class.) to make a homemade
    fence charger and use a coil from an old car as the inductor? That
    should be good for 10-15k volts I would think, low amperage, and only
    momentary stimulus. Should be enough juice to burn through weeds and
    grass, and if it hits only about once a second or maybe twice a second
    it shouldn't do anything to the dogs but convince them not to touch

    I'm only saving maybe a hundred bucks by doing it myself, but I'll
    feel pretty good about myself if I do it. I can handle some simple
    stuff like a 555 timer to run a relay to switch the load and some
    other simple electronics. Can I make this work? Is there some better
    way (short of buying an off-the-shelf solution)?

    Thank you for your time and help.

  2. HC

    HC Guest

    Hmm, I found an article that I had missed earlier here:

    That seems to discuss what I'm looking for.

    I'm sorry. But if you happen to have more to add to that please do.
    Thank you.

  3. Rich Grise

    Rich Grise Guest

    Train the dogs to stay home.

    Good Luck!
  4. Doug Miller

    Doug Miller Guest

    So get a higher-powered charger -- such as one designed for use with cattle.
    Any farm-and-feed store will have them. End of problem.
  5. Eric R Snow

    Eric R Snow Guest

    Even though I can't help with the fence charger I do want to say
    thanks for keeping your dogs on your own property. I live in a rural
    area and I see dogs running loose all the time. They get into the
    garbage and they kill the chickens. Then they get shot or poisoned or
    run over. Either by accident or on purpose. And it's the dogs that pay
    for their owner's irresponsibility. So thanks again for keeping your
    dogs confined to your property, they will live longer and be happier.
  6. Ross Herbert

    Ross Herbert Guest

    I think that unless you can prevent the weeds from coming into contact
    with the conductive tape then substitutiing an even more powerful unit
    will not solve the problem. The higher voltage from a more powerful
    unit will break down any resistance via the grass even better than the
    low power unit so it isn't going to help.
  7. Bob Masta

    Bob Masta Guest

    You might want to consider the "invisible fence" type of system, where
    the dog gets shocked through its collar if it passes over a buried
    wire. Seem to work really well. The only downside is that if the dog
    bounds over the line (chasing a squirrel, say) the deterrent shock
    also deters from getting back in.

    Best regards,

    Bob Masta

    D A Q A R T A
    Data AcQuisition And Real-Time Analysis
    Scope, Spectrum, Spectrogram, Signal Generator
    Science with your sound card!
  8. Doug Miller

    Doug Miller Guest

    For five acres, that's going to get really expensive.

    Best solution to the problem is a more powerful fence charger. There are units
    made specifically for burning through grass and weeds that grow up into
    contact with them.

    To the OP: repost your question in misc.rural and see what kind of suggestions
    you get there.
  9. Ross Herbert

    Ross Herbert Guest

  10. You might want to post also on rec.pets.dogs.behavior. I've gotten advice
    there, good and not so good, for me and my dog Muttley. Watch out for the
    resident troll Jerry Howe, who posts long winded tirades, under various
    long nyms. My dog and I have a "reputation" there as well. I documented the
    early part of it on

    Paul and Muttley
  11. jasen

    jasen Guest

    well, the wire needn't be buried, the existing fence wire could
    probably form most of the loop.

    otoh the with the right sort of plow you can put wires underground
    (for shallow values of underground) fairly easily.
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