electric fencer

You could make a small coil and connect it to a galvanometer:

and pass one of the HV fence wires through it. If the resistance it too low you might get an idea of current flow. Good for a relative measurement (just not quantative).

If it is a DC pulse, like the device my father had many years ago, than a multi-meter with a series resister will measure voltage with the caveat that as you are measuring between the fence and ground your ground connection will have a large effect on the voltage that the meter reads.

Pissed on it, did you ?

I'd add a neon lamp and a high-value series resistor, maybe a string of a couple dozen 100 K resistors. You need a bunch in series so they don't arc over. As long as the lamp is blinking, it is still working.

Jon

Is that to keep stray cats away? (Word must have gotten out among the cat community.)

Karl,

Most fence chargers are prtetty simple, I have schematics of a few designs. What brand is yours?

Units with a meter typically connect the meter to a 1 or 2 turn secondary on the output transformer. Depending on the design of your charger, the meter curcuit can be as simple as a diode and a meter movement or somewhat more complex.

It would be well worth your while to open the charger up and take a look at what you have. It could be a bad meter movement, a bad diode or even a dead insect in the meter movement blocking motion. Supposedly, the movement is sealed os a bug can't get in, but as you probably know they can get into surprising places.

WayneJ

This is for my very large rats with hooves. (deer) Takes a SERIOUS pop to tell them not to come back.

I also use it around the sweet corn patch for the masked bandits (racoons)

Karl

Its a Parmak precision brand. Made in USA - KC MO

A proper repair would be huge. I did find this on the web

But likely, the repair will be about the same as a new one. Mine is a 6 Joule 7K volt rated unit. Now, I see you can get 10 Joule 12K volt units. Maybe its time to upgrade.

For years, I've moved a metal post close to the wire to make sure it pops a good arc. I'm thinking, make this accurate for a measurment. I'll just set up a stop with a threaded bolt, probably use 3/4x10 so each turn is 0.100". I know the fencer pops 1/4 to 3/8 when in top form, if it won't pop more than about 1/8 its time to find the problem.

Make sure the insulators are clean. They will bleed off a lot of the energy if they are dirty. It goes without saying, but turn it off before you do the inspection. ;-)

See if you can find an old Pomona or B&K TV HV probe with a built in meter. You'll need to add a couple diodes to rectify the AC, but then it's a simple matter of clipping the lead to ground, and touching the probe to the wire.

Here is an example of a B&K on Ebay:

Fluke, Heathkit & others made probes to use with a 10 Megohm input impedance meter, but they cost as much, or more than the probe type..

Go to your local farm store and buy a fence tester. You need one anyway to find breaks in the fence. They are a series of high value resistors with neon bulbs across the resistors.

Use the tester when you need to, or just hook it permanently to the charger.

Paul

Make sure to clean the body oil off them, and that you don't exceed the rated voltage for each resistor.

BINGO

Didn't know such a thing existed, I'll order one.

Karl

Yeah, a 6 Joule unit will get your attention if it hits you!

I have a partial schematic for a smaller Parmak. Parmak uses a somewhat more complicated metering circuit than some. One turn of wire around the outside of the output transformer connects to a circuit consisting of a rectifier, followed by an opamp integrator and meter driver.

If you are comfortable working on the circuit I'll be glad to send a copy of the metering circuit. Although it's from a different model it's likely to be quite similar except for a few component values. It would be quick and easy to check the diodes, meter movement and most of the caps and resistors without disconnecting anything.

Your test unit should work, but of course you have to go up and connect it each time you check the fence. In my experience, the cheap test units with multiple neon lights indicating voltage are good to check the output, but won't last if left connected permanetly.

Be glad you have deer and not elk to keep out. The elk around here will go through a 6 wire high tensile fence as if it wasn't there, hot or not. They seem to prefer to bust through even if the fence is low enough to jump.

WayneJ

They make Electric Fence Testers nowadays. For instance:

"Get accurate and reliable voltage readings of your fence line or fence charger with simple, one-touch operation. Use the Zareba® Digital Electric Fence Tester to measure fence line and fence charger voltage. -Combines digital accuracy with ease and convenience -Rugged easy-to-carry pocket-size case made of heavy duty ABS plastic -Digital accuracy from 500 to 9,900 volts -Large easy-to-ready LCD display -volt battery operation (battery included) -Automatic on/off that prolongs battery life..."

Just see how long a spark you can draw from it. The old "weed chopper" woultd throw a good hat quarter inch spark and burn off 1 inch sumac.

Tektronix made a really nice one -- good up to 40 KV. But beware. It takes a squirt of a HV dielectric fluid (which is really one of the now-banned refrigerants), so you are unlikely to get the full voltage range out of it. (And no, I don't remember if I ever knew what refrigerant they used -- just one of the FREON family. :-)

If you have some, a squirt will usually last a year or two before it all leaks out.

And it has four or five trimmer adjustments for proper waveshape at various frequencies. A *big* box on the BNC (with a collet lock-on to keep it from jiggling off. :-)

Enjoy, DoN.

If there is grass or somesuch on the line, a spark will develop at the charger if you disconnect the wire and hold it far enough away from the terminal to form a 1/16 in or so wide gap.

What kind of hat did it throw? ;-)

A newer refrigerant is being discussed as a possible replacement on the Tekscope Yahoo group right now.

I used to use my Heathkit HV probe on low voltage circuits, to prevent loading in very high impedance circuits. The solid state Heathkit had some very low voltage ranges, and the probe let you multiply them by 100.

A guy on the Tekscope Yahoo group builds a HV plug-in for the 7000 series. It will work to 7 kV. There is also a thread on how it's impossible to make affordable replacements for the extruded rails for

7000 series plug ins. One claims it can't be done in small quantities for under $200 a set. He refuses to believe that it can be done in a decent home metalworking shop. I have no 7000 series gear, but from what I remember it wouldn't be that hard to make an acceptable replacement since they are looking to build custom plug-ins.