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Forum Index : Electronics : fence energiser autopsy
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yahoo2 Guru  Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
Had good intentions of sending it away to be fixed but it has sat on the shelf for quite a few years. it still powers up and triggers the pulse but no hurty sparks come out, so I figure there cant be a lot wrong with it. it is a re-branded Stafix unit from NZ. from memory it can power more than 300 km of wire and the output should be 7500 volts at the red terminal. Anyway I will post a couple of photos when i open it up so you can see what makes it tick! I'm confused, no wait... maybe I'm not... |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Cool. Would be interesting to see whats inside. I have a couple of the old 6 volt energizers with the sprung flywheel that goes "twang, twang, twang...". One works, been using it for a year now, nasty bite! Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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BobD Guru Joined: 07/12/2011 Location: AustraliaPosts: 935 |
That's one long fence.  |
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| Georgen Guru Joined: 13/09/2011 Location: AustraliaPosts: 462 |
Can it be re-purposed for other than fence applications? George |
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Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
Well yes, it could. I had a problem with cats doing their 3AM love songs under my house, my house is an old one on stumps. A wire at cat nose level strung on little plastic insulators on the perimeter stumps did the trick. I powered it from an old sealed CRO HV unit but a fence energiser would work just as well. One almighty miooouuuwww was heard the next night and they never came back. Klaus |
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Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
Im not supprised, One would expect a few thousand volts across the nose would dampen any thoughts of love making. 
I dont mind cats and cat owners, but when their cat becomes their cat in my yard then "game on" 
As for the "Spitfire" on average its a step up coil charging a high voltage cap that is discharged into the fence, and often the cap becomes weak, there is some basic circuitry driving the coil and cap, that can fail, but not often the case. Pete. Sometimes it just works |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
that would be my guess pete, one of the high voltage pulsed caps has failed or a diode that across the cap. I pulled the top off tonight, here is a photo inside. 
section 1 is the mains input with the standard MOVaristor, fuse, a couple of diodes and a capacitor section 2 low voltage pulses come from the transformer (white wires) and drive the lights on the front of the case item 3 AC capacitor item 4 wound coil/inductor the three wires coming out of the transformer are green-ground, red-full power, yellow-half power. the wires that drive the transformer from the capacitors are underneath the board. I will get a few closeup shots when I pull the board and transformer out to get at the terminals of the capacitors with my tester. I can vouch that it has got plenty of grunt, if I hold onto a wire that is not electrified it will make my arms twitch just from the induction of the electrified wire close by.  I'm confused, no wait... maybe I'm not... |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
View of the 30 uF pulsed Cap, coil and the control board. 
these are the boys that take the brunt of the load 1200VDC 20uF pulsed type P124 I think one of them will be cooked. I'm confused, no wait... maybe I'm not... |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
Looking at the first photo above I can see a SCR just in front of the coil and another in the second photo next to the smallest cap, it looks like BT136 written on one of them. Hopefully they are both triggering and resetting when they should and I dont have to fiddle with any of that. I'm confused, no wait... maybe I'm not... |
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Dingdoc Regular Member  Joined: 23/09/2009 Location: AustraliaPosts: 76 |
Thanks for posting this yahoo2. There always seems to be plenty of interest in fence energisers and very little info about them online. As regards to its workings, and from what I can make out from the photos, it appears to be a standard configuration based on charging 1 or more high voltage caps up to around 400v+ and then dumping the charge through a low impedance step-up transformer at around 1hz to produce a pulse of several kV at quite a high current (many amps!) The rest of the circuitry is tasked with pulse timing, voltage regulation, wave shaping, lightning protection and reducing RFI. I would guess that the black trannie is the low impedance step-up and is potted to stop HV flashover. It looks like it has a tapped secondary for high and low power from the red & yellow terminals on the front. One of the triacs is probably used to switch the charge from the reservoir cap(s) to the trannie through the two white wires (primary). The wound inductor (LHS) and the block caps on the RHS of the main board are for wave shaping to protect the triac and reduce RFI There is possibly a capacitively coupled LV power supply to power the timing circuit on the small vertically mounted pc board. The components most likely to have failed would be the tranny (o/c) the cap(s) or the triac, although from the photo it almost looks like the case has had water in it. Just as a word of caution when working on this, watch out for those caps. If they don't have bleeder resistors they could remain charged for a long time and could be lethal if they bite you! Hope this info helps and regards to all on the forum - I haven't been on for a while. Trev |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
hi Trev, no water in it, just 20 years of dust and mild condensation! all the bleeder resistors are still working thank goodness. photo of the back you can see the transformer primaries that I mentioned earlier, a couple tracks are cut with components added, if you look closely I have numbered the SCR's so you can see the track they are controlling, No2 is next to the coil. 
I'm confused, no wait... maybe I'm not... |
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| Dingdoc Regular Member Joined: 23/09/2009 Location: AustraliaPosts: 76 |
Sorry, I should have read this more carefully but the photo makes it all clearer! The yellow and black are definitely the transformer primaries - much more substantial. SCR no.2 looks like the switch to dump the cap charge into the primary. Not sure about SCR 1 but possibly switched to control pulse shape/duration. I guess the empty cap pads would be for the voltage doubling charge circuitry for the 110V version. Also sorry to sound like a nanny over the high voltage but it probably serves to warn others about the dangers of these things - they would be on a par with microwave oven caps which are reputed to kill quite a few, including experienced people servicing them. I noticed in the "Other Stuff" section that Bryan2 successfully built the Silicon Chip version of an energiser and that has had quite a few views. He had the same problems with transformer flashover as I did when I built mine, which is still sitting in a box waiting for a re-build. The Oztules version I built still seems to be going strong on a local property. I look forward to reading more on your progress with this. Trev |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
thats OK, these things still scare the bejezus out of me, I have been bit by satellite decoder power supplies enough to know that I dont want a big kick. I should do a post about how not to kill or maim yourself before I go any further. The damn things are like zombies even after discharge some are still not entirely safe. I dont understand the fascination with fence energizers, I am only fixing this one because I will need it next winter, I would much rather use the portable battery ones and short temporary fences or not at all if there was an alternative. the empty cap pads are bypassed by a wire link for 230V that would be replaced by diodes for lower voltage versions. I dont know how many versions use the same board, it looks like quite a few. I am not rushing into this, I am still getting over the lurgy and feel like crap, a few minutes sitting down and my kidneys start to hurt, plus there is other work I am not getting done so it is relegated to a few minutes on the weekend ATM. cheers I'm confused, no wait... maybe I'm not... |
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