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Help with fence charger schematic

barryg

Jul 24, 2017
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I need to be able to upkeep my electric fence charger around my honeybee yard in order to keep the bears out. I have a dry location with 120 v ac available. I had a good charger that kept the weeds down and I think it was rated at 6 joules. lightening strike damaged this unit and the only replacement I have is a unit that seems much weaker but does work. I can't afford to keep replacing the better unit but I may be able to build one that I could also repair. I am requesting help for a diagram of a 6 joule electric fence charger that uses 120 volt a/c power
any help will be greatly appreciated
thanks
barryg
 

Minder

Apr 24, 2015
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There are quite a few circuits out there if you Google, some claim good results ignition coil based.
Fairly simple.
Maybe reverse engineer the defective one and repair it, there is not much to them.
M.
 

kellys_eye

Jun 25, 2010
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Minder

Apr 24, 2015
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Well they are easy to construct, ignition coil etc.
Nothing lost by trying a fix!
M.
 

duke37

Jan 9, 2011
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I have repaired several electric fence chargers, from the electromechanical type to mains driven simple high voltage transformer - frightening.

The lightening damage may be restricted to a few components. I have never seen a faulty output transformer.. I saw no more damaged chargers when an inductance was added to the output.
One of the worst damaged had the PCB in two halves. Epoxy and wire links solved this. A year later if turned up again, I refused to mend it until I was told its history. It turned out that a plough (US plow) had yanked the fence wire. A crock clip solved the ongoing problem.

An ignition coil has been disparaged, I think this is due to too high a resistance.

I would make a 12V charger with a mains PSU to give isolation. Then an inverter to charge a capacitor to the required energy. The capacitor would then be discharged into the output transformer using a SCR. I timed it with a neon and small capacitor.
Where will you get your pulse capacitor and output transformer from?
 

73's de Edd

Aug 21, 2015
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Sir barryg . . . . .

The magical words were . . . .a la Minder . . . . .

Maybe reverse engineer the defective one and repair it, there is not much to them.

Since you have already BOUGHT . . . a purposed GOOD one . . how about providing some good squared off and close up , full in the frame, well focused photos of both the component and the foilside of its board as well as a close up of the placement of the basic innards within the units case.

Also its brand and model number.

Then ALL will be able to inspect, evaluate and possibility of repair feedback..

73's de Edd
 

barryg

Jul 24, 2017
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I wpuld be happy to do that and it would be very interesting to me but I returned the broken one to the manufacturer (silver streak) and they gave me another one thru the dealer but it was a little different and I don't think it was as strong as the other one
the first one was a silver streak super 50 with a red and gold face plate the other was a super 50 with a white and black face plate
anyway my set up is a little different than most I am protecting a small bee yard approx. 30 x 40 feet but I used livestock panels ( approx. 1/4 inch galvanized rods make up these panels) and connected them together rigidly to form the fence with some homemade insulators of 1/4 inch fuel tubing and 3/4 inch grey outside type conduit around that to clamp the fence to the wood posts
I live in the mountains of east Tennessee and bears are definetly a problem and once they make access to the honey they won't stop coming back also there are a lot of smaller pests for honeybees that the panels help keep out
so I think I need something pretty strong and I have electricity available on site so I would rather not use a battery for power
I am trying to make contact with the manufacturer to get the other style back and I will post pics then and if I had known about this website I would have started there
so,
any help on a strong charger schematic would be greatly appreciated
also any comment on the best way to insulate the panels from the wood posts would be good I thought about some leftover ceramic tiles I have handy maybe they would help with the insulation?
 

barryg

Jul 24, 2017
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barryg again'
how do you determine the amount of joules on a circuit like this?
 

barryg

Jul 24, 2017
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This is very interesting
I'm going to study that some but in the meantime I'm curious what size capacitor would produce 5 or 6 joules in a fence charger and I don't know the difference between one that runs off a battery and one that uses AC supply
Guess I'm starting from scratch
Is it a capacitor or a transformer that provides the output sparks
 

kellys_eye

Jun 25, 2010
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If you can't be bothered with the math(s) - and I usually can't either - there are online calculators that do the dirty work for you.

https://ncalculators.com/electronics/capacitor-charge-calculator.htm

Fence energisers work by discharging a capacitor through a transformer to 'multiply' the voltage to the levels required to create the spark. The capacitor is often charged to 100V or more (300V being common) using 'boost' circuitry powered from a battery.

If you read the article I posted above (schematic for a fence energiser) it explains the processes involved - all energisers work on the same principle but may vary (slightly) in how they achieve the final result.
 

duke37

Jan 9, 2011
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5J is quite a powerful fencer charger.
The energy in a capacitor is C*V^2/2
For 100V capacitor need 1mF = 1000μF
For 500V capacitor need 40μF
The capacitors are often special pulse types which can stand the large current when discharged. Electrolytic capacitors are not used.

The output voltage needs to be 5kV or more to punch through the fur or hair of the target.
100V capacitor the transformer should be 50:1.
500V capacitor the transformer should be 10:1
The transformer will be rather special with good insulation on the wire and insulation between winding layers and excellent insulation between primay and secondary. Transformers usually have iron laminations, I do not know why ferrite cores are not used.
 

barryg

Jul 24, 2017
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Understood
I think I'm going to study the information supplied here and design one for myself that I can rebuild when necessary
I will post the design and ask for input and maybe some help estimating the power output so I don't electrocute anyone!
Thanks again
 

barryg

Jul 24, 2017
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Mr. duke37 and or mr. kellys-eye
would either one of you be willing to share an email address?
I am the chief of our local fire department so mine is a city address:

[mod note: email removed]
 
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kellys_eye

Jun 25, 2010
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Given the nature of your request it may better serve the wider audience if we discuss any design openly - after all, this is what the forum is about! There are no secrets here (excpet my stash in the back office......oops...)
 

barryg

Jul 24, 2017
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Understand
I'm gonna take some pictures of the 2 I have and maybe reverse engineer them as previously suggested and then maybe I can get some help increasing the output 25% or somewhere in that range and build a couple more to have spares
Incidentally the one with weak output was shorting to ground at the transformer
I'm waiting on a new one and will try rewinding the old one
 

WHONOES

May 20, 2017
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Hi. I am looking at a design for an HT provider that should fulfil you requirements. You will need to drive it using a 12 to 15V dc power supply. A transformer - rectifier off of your 155v ac supply should do that bit.
If this is no good, say so here and I will stop.
The circuit I have in mind will use commonly available parts.
When the circuit is complete I will write it up so that you can build it.
 

barryg

Jul 24, 2017
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This sounds great
I have an old 24 volt power supply that came off a electric wheelchair it seems pretty substantial for a power supply if I need to I can figure out a way to reduce the voltage and start there and duke37 also recommended this for some isolation
ill send some pics of this power supply with the specs
 

barryg

Jul 24, 2017
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also I have the wiring to rewind the existing transformer (above pic) would like to try to boost it a little
the primary has only 9 winds of 16 awg wire and the secondary has 224 winds of 22 awg wire. Would 22 more winds of secondary wire increase the output by 10% ? and I've got 20 awg instead of 22
 
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