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Anything I can do with an electric fence charger?

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Josh

Wed Apr 13 2011, 05:24AM

Registered Member #938 Joined: Sat Aug 04 2007, 05:39AM
Location: Honokaa,HI,USA
Posts: 65

I acquired an electric fence charger and I'm hoping to utilize it for something.
It seems to contain a 2uf capacitor, 1 2n3 series transistor, a rather small transistor,
and a half dozen or so random resistors(some are 1/4 watt other are a couple watts).

The whole board runs off of 120VAC,
and feeds it into a rather typical looking iron core transformer.
It puts out a pulse every second or so.
No arcing(it's odd since most chargers from my experience create visible sparks), however it made a neon bulb glow bright blue with each pulse.

I was thinking there is a way to make it pulse at a higher frequency(my knowledge of electronics isn't very deep as you can see) and perhaps with some luck have it feed a tiny tesla coil like a ignition coil would. Perhaps it would function as a psu for a marx generator?
Am I rather off base or can I use it for something interesting?

magnet18

Wed Apr 13 2011, 11:49AM

Registered Member #3766 Joined: Sun Mar 20 2011, 05:39AM
Location:

Posts: 624

A blue neon? Interesting
It might be possible, or it might not be, depending on the board and circuitry, look for a timing capicitor.
And you'll probably get more help if you post pics or a schematic.

Ash Small

Wed Apr 13 2011, 11:58AM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

From what you.ve said, and I'm only guessing here, does the power transistor and small transistor form a darlington pair? does the small transistor have an associated capacitor/resistor, where the value of the resistor controls the charging rate of the capacitor and, therefore, the frequency of discharge?

(If they don't form a darlington pair, do the two transistors form an astable multivibrator?)

Please post a schmatic, or at least a photo.

Shrad

Wed Apr 13 2011, 12:57PM

Registered Member #3215 Joined: Sun Sept 19 2010, 08:42PM
Location:
Posts: 780

for what I recall, fence chargers usually use a transistor and an SCR to form a simple pulser

Mads Barnkob

Wed Apr 13 2011, 02:19PM

Registered Member #1403 Joined: Tue Mar 18 2008, 06:05PM
Location: Denmark, Odense C
Posts: 1968

Having one of these circuits lying around somewhere, I would say that the pulse transformer itself is the limit. Mine is a plastic encapsulated transformer the size of something like... 50 - 80VA

ScotchTapeLord

Wed Apr 13 2011, 08:39PM

Registered Member #1875 Joined: Sun Dec 21 2008, 06:36PM
Location:
Posts: 635

You can use it to charge an electric fence.

Xray

Thu Apr 14 2011, 03:54AM

Registered Member #3429 Joined: Sun Nov 21 2010, 02:04AM
Location: Minnesota, USA
Posts: 288

Josh wrote ...

It puts out a pulse every second or so.
No arcing(it's odd since most chargers from my experience create visible sparks), however it made a neon bulb glow bright blue with each pulse.

I was thinking there is a way to make it pulse at a higher frequency(my knowledge of electronics isn't very deep as you can see) and perhaps with some luck have it feed a tiny tesla coil like a ignition coil would. Perhaps it would function as a psu for a marx generator?
Am I rather off base or can I use it for something interesting?

If your fencer doesn't produce a spark of at least 1/2 inch long, then it is defective. Your neon lamp lights because a neon lamp needs only about 85 to 100 volts to ionize the gas, so based on what you said, I suspect that the fencer is putting out a high enough voltage to light the neon lamp, but not enough to shock a cow.

As for your "blue" flash, I've seen neon bulbs do that if you hit them really hard with a charged electrolytic capacitor. They will flash with a bright orange-white light, and sometimes they will actually flash blue-white, depending on the condition of the gas, the electrode spacing, and the voltage/current magnitude of the pulse. If you do this repeatedly to a neon lamp, you may get only a few blue or white flashes before the bulb becomes permanently damaged.

As far as using a fencer for other projects that you mentioned..... There really isn't much you can do with a fencer other than shocking livestock. They were designed to generate a hv pulse with a pulse repetition rate of about one second, and you really can't drive a Tesla Coil or flyback transformer with one.

Josh

Thu Apr 14 2011, 05:08AM

Registered Member #938 Joined: Sat Aug 04 2007, 05:39AM
Location: Honokaa,HI,USA
Posts: 65

Xray wrote ...

Thanks for your input.
I'll depose of it since that was my hunch that it's was shot,
plus from what your saying it's not worth it anyways.

magnet18

Thu Apr 14 2011, 08:37PM

Registered Member #3766 Joined: Sun Mar 20 2011, 05:39AM
Location:

Posts: 624

Scrap it fer parts!
still some good stuff in there :D

Josh

Fri Apr 15 2011, 02:09AM

Registered Member #938 Joined: Sat Aug 04 2007, 05:39AM
Location: Honokaa,HI,USA
Posts: 65

For sure :)

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