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agm2003 24th August 2007 03:20 PM

How to modify electric fence Output?
I need help.

I would like to keep my our (Rat Terrier & Boxer) out of wife's flower bed. I have an electric fence energizer (several years old "farm" variety) available to use. This is PULSE type,"weed burner", (and "5 mile" I think??). I can get make/model, photo, etc if it will help, and have digital multimeter to check output.

MY QUESTION: For a short fence with pets, how can I REDUCE voltage on the wire--I don't want to hurt them (physically or psychologically) just get them to stay out of the flower bed.

I was thinking about putting a resistor in-line, but don't know how many OHMS or whether to put in on "Fence" or "Ground" sides?

Any Ideas?

agm2003 25th August 2007 12:21 AM

Clarification of specs
The label on the "energizer" states the following:

20 mile (this corrects original post)
Solid State
Intermittent Output
Ser# S-6137

Thank you in advance for any help.

TwoSpoons 27th August 2007 01:39 AM

I used to work in the industry designing these things. Your pet WILL get hurt - thats the whole idea! But its not physical damage - just pain. To reduce the effective output use a 10 watt ceramic wire wound resistor in series with the 'hot' side of the output. A k or two would be about right. It MUST be a wirewound resistor - not film. Film types blow up if the fence arcs to ground. Wierd but true - short circuit is OK, arcs are not!

Test the fence on yourself before you unleash it on your dog. If the fence bites too hard, add more ohms. It wont kill you (they're designed not too . :D ) but it will hurt. Don't bother with the multimeter - it wont tell you anything useful, even if it survives.

Edit: just looked up the specs on that energiser. Its only half a joule output - thats pretty tame. I've been hit by bigger beasties than that. The 16kV peak might give your trouble with flashover - better make that two, or maybe three resistors in series. Be sure to use the BIG 10W ceramic ones.

agm2003 27th August 2007 12:29 PM

You are the man! Thank you so much for the information! That is exactly what I was needing.

I'll be off today to find a handful of resistors!

Thanks a bunch!

agm2003 27th August 2007 12:48 PM

Points for clarification...

1--You said "two, or maybe three in a series" I'm taking that to be mean start off with something like three x 500 ohm resistors (for total of 1.5k) in the series (as opposed to three x 1k in a series for starts).

2--Is it ok to go "end to end" on resistors, or do I need more "airspace" by using jumpers between resistors to prevent arcs?


Pano 28th August 2007 12:00 PM

When you get this working, it will very effective.

Back when I was working with horses we had plenty of electric fences. At home we were having problems with neighborhood dogs getting into our trash cans at night. It was long enough ago that the cans were metal. (the 70s)

A wire from the electric fence unit was all it took. Connected it to the garbage can and waited for night. Sure enough, "rattle, bang -YIP-YIP -YIP!!!" Never a dog near the can ever again. :devilr:


BTW Two Spoons, I notice you are in "Waiuku", NZ. Did you know the county seat of Maui is "Wailuku". I'm not sure what Waiuku means in your local version of Polynesian (mud flats?) but here it would mean "Flea Water." ;)

agm2003 28th August 2007 01:55 PM

"When you get this working, it will very effective."

While I was setting this up (just to see if the energizer still worked), I had told my wife to be very careful to not touch the wire. Something happened and caused one stem of one of her plants to touch the wire, which of course shorted to the ground and caused an arc to the plant. To "rescue her precious plant" when she touched the stem of the plant to move it (while being careful not to touch the wire) but she became the best ground! OOPS! She said the fence worked! She now remembers where to unplug the energizer!

Pano 28th August 2007 08:28 PM

Ouch! You are supposed to use it on the dogs, not the wife! :eek:

I bet she'll remember where the plug is.

FWIW, my step son used to install the invisible fences that use the radio activated shock collars. He said ti was very effective. (And expensive)

So here's a little trick. The invisible fence systems use little white flags in the ground to tell the dogs where the limits are. They learn to stay well clear of the flags, even when there is no shock. You can use that to your advantage. ;)

TwoSpoons 30th August 2007 04:28 AM

3 x 500 ohm is what I meant. Stick 'em in line, rather than beside each other.

The accepted meaning of “Waiuku” is muddy or discoloured waters. Stands to reason: it sits at the end of a river estuary. I know 'wai' means 'water'; 'uku' means 'white clay' near as I can make out.

agm2003 30th August 2007 06:03 PM

Thanks so much for your help!

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