How to make an Electric Fence

Thread Starter

Selvedin

Joined Jan 25, 2021
21
Hello guys, I need to make an electric fence for my sheeps. Can you please help me and give me an easy method to make it?
 

Thread Starter

Selvedin

Joined Jan 25, 2021
21
Depending on where you are located you can find a lot of products to do this, for example, in the US:

https://www.tractorsupply.com/tsc/catalog/electric-fencing

But, in any case, the way to do it is to buy commercial products, the complexity of safety related things and all the details of a successful deployment make homebrew very dodgy unless you didn't have to ask this question.

Hello, I have one, but it's too weak, that's why I want to make my own with a higher voltage output.
 

DickCappels

Joined Aug 21, 2008
7,746
Not long ago a person around where I live made his own electric fence. It ended up killing his son.

I would not mess around trying to make one. Teating it for safety would be a problem.
 
Buy a commercial fence energizer. It may be expensive but you wouldn't want some DIY thing to be too strong and kill your sheep, or yourself for that matter.
 

crutschow

Joined Mar 14, 2008
27,761
I have one, but it's too weak, that's why I want to make my own with a higher voltage output.
The thick wool of the sheep likely prevents it from getting a shock.

There are a number of fencer designs (here) that use an ignition coil to generate a higher voltage than a typical fence charger.
The are generally safe if powered from a transformer supply or a battery, since an ignition coil can't generate a lethal amount of energy (otherwise there would be a lot of dead car mechanics).
 

Thread Starter

Selvedin

Joined Jan 25, 2021
21
The thick wool of the sheep likely prevents it from getting a shock.

There are a number of fencer designs (here) that use an ignition coil to generate a higher voltage than a typical fence charger.
The are generally safe if powered from a transformer supply or a battery, since an ignition coil can't generate a lethal amount of energy (otherwise there would be a lot of dead car mechanics).
The one I have is also homemade, it uses an ignition coil and a relay. The power is generated from a 12v battery charger. It's pretty weak, my sheeps can play with it
 

ericgibbs

Joined Jan 29, 2010
13,670
hi Selve,
Sheep are very difficult to 'shock' , all that wool and Lanolin.

Have you tried different settings for the relay Dwell time.?
I managed to get my design working with sheep OK, on our South African farm

Post you circuit diagram.

E
 

Thread Starter

Selvedin

Joined Jan 25, 2021
21
hi Selve,
Sheep are very difficult to 'shock' , all that wool and Lanolin.

Have you tried different settings for the relay Dwell time.?
I managed to get my design working with sheep OK, on our South African farm

Post you circuit diagram.

E
Hello Eric,
yes, they are. But often they taste things with they tongue, that's where sparks come to play haha

No I didn't, it switches about 5x in a second, which should be enough.
Do you think a better capacitor could help?
 

ericgibbs

Joined Jan 29, 2010
13,670
hi S,
I can see lots of problems with that fencer unit, it will never give you the high voltage required for a good electric fence.

This my circuit diagram.

E

Added an image of your circuit.
The highest voltage from that circuit is approx 10kVolt
 

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Ian0

Joined Aug 7, 2020
3,281
Would an IGBT be more reliable than a relay? There's quite a large flyback voltage on the primary of the coil. There are IGBTs made specially for the purpose?
What does the output waveform look like with a realistic load? Capacitance from wire to earth might be only a few pF per metre, but with 100m of fence it's getting to be around a nanoFarad, and that should make it ring about 2kHz with your value of transformer secondary inductance.
 

crutschow

Joined Mar 14, 2008
27,761
I would consider a capacitor discharge circuit (below) described here.
More detail on the operation is here.
The advantage is that the storage capacitor (connected to SCR anode) value can be increased if needed, which increases the spark energy to handle the capacitance of a long fence.
The Kettering type circuit has a limit on the spark energy as determined by the inductance and saturation current of the coil.


1618066140726.png
 
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Thread Starter

Selvedin

Joined Jan 25, 2021
21
hi S,
I can see lots of problems with that fencer unit, it will never give you the high voltage required for a good electric fence.

This my circuit diagram.

E

Added an image of your circuit.
The highest voltage from that circuit is approx 10kVolt
Hello Eric, sorry for the late answer and thank you for your diagrams.
I saw this voltage booster module on the web, could this be the solution for my electric fence?
Can I just put one cable into the earth and the other on the fence cable?
 

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