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Bryan1

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Joined: 22/02/2006
Location: Australia
Posts: 1344

Posted: 12:31pm 18 Jun 2015

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G'day Guy's,
Got cows on the farm and they think they can just walk thru the fence and crap everywhere around the house so with the owner of the cows put in an electric fence. He supplied a 240 volt electric fence energiser along with a 300 watt inverter but I found in a day it sucks a 12 volt battery dry.

Years ago I got a couple of those kits and made one up to find it arcs out in the high voltage transformer but works intermittently. So decided to wind a new transformer and put it in, had a 10mm gap with the test wires and got an arc across for about 5 minutes then it arced out in the transformer again. So went and made another one to find the same bloody thing works for a short time then arcs out.

Was getting late last night and started on another one making sure the output was nicely insulated but I am thinking I may need to make up a jig for winding so each layer of 0.25mm wire is purfect.

Anyway will finish winding up the current one and see it it works and if not time to make a jig.

Ah the frustrations of DIY but I have to say although several high voltage tranformers have been on the circuit it still just plain works.

Cheers Bryan

Bryan1

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Joined: 22/02/2006
Location: Australia
Posts: 1344

Posted: 04:38pm 18 Jun 2015

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G'day Guy's,
Well got the transformer wound and as Shauns brother has watching over laughing it turned out I had only enough 0.25mm wire to get 8 turns on so only did 6 instead of 7 on the primary. Soldered it back in and YAY spark bridging nicely then a few minutes later GRRRR but only for a few pulses then back to spark.

Anyway got it on the fence now and a quick with with a $5 multimeter did show it working so I'll leave it for a day then check again.

Got 2 off 5 watt pv panels connected and checking them today with pea soup weather they were putting 200-250mA which is more than the 50mA needed to run the circuit. Next jobbie is making charge control circuit with some datalogging so I can see how it performs.

Got a second kit here so will make that up and make a jig for winding the next high voltage tranny as it does look like it has to be wound elperfecto or the high voltage will bridge out.

Cheers Bryan

Dingdoc

Regular Member

Joined: 23/09/2009
Location: Australia
Posts: 76

Posted: 11:50pm 20 Jun 2015

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Hi Bryan
I also built one of these some years ago and experienced the same problems.
The control and charge pump part of this circuit seems to work quite well but the transformer is just too small to handle the voltages generated.

It may be worth trying to wind a physically larger transformer and keeping the windings well away from the core and each other.

If you haven't seen this yet it's worth a read -

http://www.anotherpower.com/board/index.php?topic=731.0

I built one of these for a friend based on oztules design. He has just installed it and I am waiting to see how it goes.

It's certainly much bigger and heavier than the SC model.

I feel sure that an output tranny based on this design could even work with the SC board although the impedance of the primary may be too low for the single triac to handle - could be worth some experimenting though.

For the oztules version I built I used a big heavy core made with laminations cut from an old microwave transformer. I insulated all of the individual layers of windings with layers of captan tape and used narrow strips of cardboard cut from manilla folders for the spacers at the sides of each layer of wire to keep them in place and away from the (iron) core. From memory the primary was around 10 or 20 double turns of 1mm wire (wound 2 in hand) and the secondary was about 200 turns of .5mm wire. The former was built from some formica-like board and epoxied together similar to the design on the other forum. It certainly did not show any signs of breakdown during testing!

Anyway, have a read on the link and see what you think. It is rather long but the info is very good at explaining how these fence energisers work.
Just remember the reservoir capacitor is the dangerous part so always make sure it is FULLY discharged before touching anything on the circuit - give it plenty of time to discharge and carefully check with a meter. It can be LETHAL!

Trev

Bryan1

Guru

Joined: 22/02/2006
Location: Australia
Posts: 1344

Posted: 11:47pm 19 Aug 2015

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G'day Guy's,
Well those pesky cows decided to go thru a different fence to come over to the front of the farm so got onto the guy who owns them and on Wednesday he came around when I was out and put a hot wire from the lower point of the existing and to the boundary.
I saw it this morning when I was out there cutting some firewood so gave him a ring. I did ask him if he put his meter on the hot wire and he replied sh*tyea mate 3800 volts along the whole hot wire. So I took my meter up to check on that old battery and saw 8.5 volts and everytime it pulsed the meter went off the scale. I do know that old battery he gave me was just about stuffed but still good to see the unit working nicely on that low voltage. I moved the wires away from the output wires and got the meter ready without the pulsing.
Now the season is changing I will have to make a circuit and get a new battery even though a 10 watts of pv won't overcharge the battery.

Cheers Bryan

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