Neon and a capacitor (maybe 0.22uF) in parallel, fed from a bridge rectifier. Cost a quid or so.
-- Smert' spamionam
Why the capacitor? If the fence is pulsed, as all of ours are (at ~ 1 Hz) then just a neon with a ~1M resistor works great.
Neon as in a mains tester screwdriver neon? Are neons different voltages? The HT lead to the bird enclosure runs for about 40 yards, and passes through the roof space of a shed, the fluorescent tube it passes by "pulses" dimly, even when off. Pity it's in the shed, or that would do Thanks for replies. If the signal lamp was fairly bright could see it from the house, which would be good.
A mains tester screwdriver contains a neon bulb and a series resistor. The neon bulb is just a small glass envelope with low pressure neon and two electrodes
Not as such - you need to limit the current through them with a resistor, the value of which will depend on your voltage.
Depends what your HT circuit's like, but I suspect if you were drawing that much power from it there wouldn't be much left to mainain a good fence voltage.
The usual need for a fence detector is to check that the wire hasn't been broken.
-- Smert' spamionam
Try a wire-ended neon, one end connected to fence and other end just pointing away from the fence wire into the air. If it's too dim, extend the wire pointing into the air. This is how some of the much larger aircraft warning lamps strung along HV transmission lines work -- the floating wire leaks enough current by corona discharge and capacitively to light the lamps.
Ah. The OP simply asked for an indication that it was 'on'. And for several fences.
... and/or that it hasn't been shorted out by falling debris, weeds, etc.
I take it that licking it (like we used to do with 9v batteries to check them!) isn't a suitable option... ;)
What sort of kick do these fences give? I've never had the misfortune to experience one.
D
The secret is the grab them manfully, then they aren't too bad, but I don't recommend licking one :-) I suspect there will be statutory limits on the voltage and current, but I don't know what they are. The more powerful ones burn off vegetation as it grows against them.
Hello David
The usual method on a farm of dealing with "know it all" types is to simply not tell them about the electric fencing. Can give substantial amusement. My dog pissed on some once, he'd never go into that field again.
Battery and Mains. The smaller 6v hobby jobs give enough to be felt.
12v car/leisure batteries kick out about 4-12kv (yep, kilo volts) at absurdly low ampage. The mains one actually kick out *less* voltage, but higher ampage and hurt considerably more and can energise miles of wire.The "hurt" is a typical electric shock. If you touch with your hand, it hurts there and you get a deep pain followed by ache and tingling at your wrist and ankle. Normally gone within a few minutes. Apparently can be fatal to those with pacemakers by disrupting their signal.
Kids don't seem to get hurt as bad, but older people do. I'm guessing, but I figure this is down to resistance of the human body increasing with age?
"Ampage" - the term you are searching for an failing to identify is "current".
12V car batteries do not "kick out 4-12kV" they supply approximately 12V (usually about 12.3-12.8V). An electric fence run from a 12V battery will supply several kV from the coil.Hello Steve
Are you sure?
Which is what I said.
Guys, if anyone wants a demonstration of the effect of either battery or mains powered electric fencing, I'm /more/ than happy to connect it to petty minded pedants. I'm genuinely curious as to the restistivity of hot-air laden, anal retentive water bags when used as earthing poles.
Yes.
Well, no it isn't, your comment is reproduced above if you're unsure of that.
You were not just wrong you were out of the sand pit and far away. Get used to it.
Hate to butt in on this little tet-a-tet, but while Simon did write "12v car/leisure batteries kick out about 4-12kv (yep, kilo volts) at absurdly low ampage", I (and undoubtedly many others) understood that he meant the fence units powered by 12v batteries.
As for use of the word ampage - while it's more correct to say current, saying ampage or amperage is pretty commonplace, and understood by most.
So it was all a simple misunderstanding. Group hug?
Sorted now, and I feel a bit of a fool. Being in the motor trade I should have realized that a drawer in the workshop contained a spark indicator neon to go onto spark plug leads to check for HT to a plug. Worked fine, zero cost. Sincere thanks for all the replies!
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