ELECTRIC FENCE CHARGERS: MODIFICATIONS

g6ypk · Apr 30, 2011

ELECTRIC FENCE MODIFICATION TO USE TRANSFORMER INSTEAD OF CAPACITOR?
Hi folks. I have a major deer problem that to date no fence charger will deter.

I have a ZAREBA A5 model :115V04J-4 electric fence charger (5 Miles). I would like to convert this unit to use a car ignition coil instead.
The output from the 741 op-amp switches the gate of a small MOSFET (or it could be a JFET as I cannot read the component) to charge a large (unknown value) capacitor to give HV to the fence.

I was wondering if I took the drain of the (TO92 and unmarked) MOSFET directly to the emitter (via 100k resistor?) of a 2N2222 or BFY51 to drive a 2N3055 or similar, then used this to dive a car ignition coil. I would use a snubber to deaden the voltage peaks, of course.

Any help would be most appreciated.

I do also have a couple of transformers from ordinary none electric fence chargers and would like to use these too, if possible. Could the output from the capacitor pump the primary of one of these transformers? Easiest possible way... Thanks.

JMOR · May 1, 2011

An ignition coil is NOT worth a $**t as a fence driver. Been there done that. Problem is that ign coil output impedance is very high, around 5,000 ohms and up. That is OK if you are running a short fence, but NOT WAS for 1/4 mile and especially several miles........couple hundred feet maybe. I have one sitting here if you want to try it.....OK for city back yard dog run, but at the farm, a Dud.

g6ypk · May 2, 2011

(quoted from post at 20:21:09 05/01/11) An ignition coil is NOT worth a $**t as a fence driver. Been there done that. Problem is that ign coil output impedance is very high, around 5,000 ohms and up. That is OK if you are running a short fence, but NOT WAS for 1/4 mile and especially several miles........couple hundred feet maybe. I have one sitting here if you want to try it.....OK for city back yard dog run, but at the farm, a Dud.

there is no problem with impedance matching as this is easy to sort out. A PI network will mach any input to output impedance.
Thanks for the advice, but a little research will show you it can be easily done. Google "impedance matching" there are a few free programs that do all the math for you and all the components are cheaply available.
Regards
Alfred the not so Great.

JMOR · May 2, 2011

(quoted from post at 10:37:03 05/02/11)

(quoted from post at 20:21:09 05/01/11) An ignition coil is NOT worth a $**t as a fence driver. Been there done that. Problem is that ign coil output impedance is very high, around 5,000 ohms and up. That is OK if you are running a short fence, but NOT WAS for 1/4 mile and especially several miles........couple hundred feet maybe. I have one sitting here if you want to try it.....OK for city back yard dog run, but at the farm, a Dud.

Click to expand...

there is no problem with impedance matching as this is easy to sort out. A PI network will mach any input to output impedance.
Thanks for the advice, but a little research will show you it can be easily done. Google "impedance matching" there are a few free programs that do all the math for you and all the components are cheaply available.
Regards
Alfred the not so Great.

am fully aware of impedance matching networks, but the fact remains that the ignition coil can't deliver adequate charge into a very long fence matched or not. Go ahead & try it & let us know how it works for you on a mile of fence, or even a half mile.

36 Coupe · May 7, 2011

You are chasing your tail.The better chargers use a very low impedance transformer.The secondary windings have few turns of wire.They get their power by dumping a 450 volt charge from an oil capacitor into the primary of large wire with few turns.Scr switching is used,not mosfet.Deer can jump a 5 foot fence with ease.An ignition coil cant handle a wet fence.The charger you have is a baby.Find a Parmak SE 3. It will put a charge on a fence even with a wire laying on the ground.I have been repairing fence chargers since the 50s.Transformers have a high failure rate.I have 2 5 gallon pails of bad tranformers in the shop now that will be scrapped soon.Lightning will eat your mosfet transistors.Static electricity will kill mosfets on the work bench.

g6ypk · May 7, 2011

(quoted from post at 18:08:43 05/07/11) You are chasing your tail.The better chargers use a very low impedance transformer.The secondary windings have few turns of wire.They get their power by dumping a 450 volt charge from an oil capacitor into the primary of large wire with few turns.Scr switching is used,not mosfet.Deer can jump a 5 foot fence with ease.An ignition coil cant handle a wet fence.The charger you have is a baby.Find a Parmak SE 3. It will put a charge on a fence even with a wire laying on the ground.I have been repairing fence chargers since the 50s.Transformers have a high failure rate.I have 2 5 gallon pails of bad tranformers in the shop now that will be scrapped soon.Lightning will eat your mosfet transistors.Static electricity will kill mosfets on the work bench.

I appreciate you talents and the many years of experience gained in working with fence chargers. However, I have been a ham for 29 years and building long before that. I have built all my own equipment, mainly for microwave 23cms, 10 Ghz and 48Ghz, though 2mtr-70cms I bought for transverter use, and All HF is home brew, too and competes very well with emporium bought transceivers.

What I am trying to say is this... I am well aware of static charges and the use of mosfets,Jfets, igfets, scr and most other planner, bipolar and other types of devices.

I have taken all you have said and have decided to go another rout, and that is the capacitor discharge method. You say to go buy a Parmak SE-3.
I would still rather build my own, though a look at a Parmak SE-3 circuit diagram and a schematic. My reasoning is thus: Joules. I need a minimum of 8 Joules and, possibly , 15 Joules, but I know this is pushing the limit somewhat. But I need to stay within State and Fedral law.

Any help would be appreciated.

JMOR · May 8, 2011

(quoted from post at 23:59:32 05/07/11)

(quoted from post at 18:08:43 05/07/11) You are chasing your tail.The better chargers use a very low impedance transformer.The secondary windings have few turns of wire.They get their power by dumping a 450 volt charge from an oil capacitor into the primary of large wire with few turns.Scr switching is used,not mosfet.Deer can jump a 5 foot fence with ease.An ignition coil cant handle a wet fence.The charger you have is a baby.Find a Parmak SE 3. It will put a charge on a fence even with a wire laying on the ground.I have been repairing fence chargers since the 50s.Transformers have a high failure rate.I have 2 5 gallon pails of bad tranformers in the shop now that will be scrapped soon.Lightning will eat your mosfet transistors.Static electricity will kill mosfets on the work bench.

Click to expand...

I appreciate you talents and the many years of experience gained in working with fence chargers. However, I have been a ham for 29 years and building long before that. I have built all my own equipment, mainly for microwave 23cms, 10 Ghz and 48Ghz, though 2mtr-70cms I bought for transverter use, and All HF is home brew, too and competes very well with emporium bought transceivers.

What I am trying to say is this... I am well aware of static charges and the use of mosfets,Jfets, igfets, scr and most other planner, bipolar and other types of devices.

I have taken all you have said and have decided to go another rout, and that is the capacitor discharge method. You say to go buy a Parmak SE-3.
I would still rather build my own, though a look at a Parmak SE-3 circuit diagram and a schematic. My reasoning is thus: Joules. I need a minimum of 8 Joules and, possibly , 15 Joules, but I know this is pushing the limit somewhat. But I need to stay within State and Fedral law.

Any help would be appreciated.

or you, then, the electronica is a no-brainer.........the big hole is what to do for a transformer???

Anonymous-0 · May 9, 2011

You are thinking with your feet instead of your head. I hope you do not think the deer are touching the fence before they jump it! Maybe they are climbing over like a man would.

g6ypk · May 9, 2011

(quoted from post at 10:17:18 05/09/11) You are thinking with your feet instead of your head. I hope you do not think the deer are touching the fence before they jump it! Maybe they are climbing over like a man would.

My fence is 11 feet tall and has a 45 degree offset at the top going out another 4 feet. There is another electric fence 4 feet from the main fence two fee tall, set at the jumping level. If the deer can get over that then they are welcome to my crops.

DScott · May 10, 2011

Wow, That's quite a fence. What are the deer doing now, rappelling over it?

JMOR · May 10, 2011

(quoted from post at 13:28:39 05/10/11) Wow, That's quite a fence. What are the deer doing now, rappelling over it?

on't you remember Rudolph, Dancer. Prancer, et al? :lol:

36 Coupe · May 29, 2011

Big problem with building your own is the lack of UL label.Maine law says you cant use a fence charger that doesnt have UL rating.Many people do.I do tell them that the old chopper chargers started many grass fires because of the long on time.

ELECTRIC FENCE CHARGERS: MODIFICATIONS

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