Electric fence operation problem

2 stage derivation of (should be) 1800V pulses. Fence had failure in the first stage probably due to intermittant corroded battery supply contact. Anyway the 15A 60V 8N06 powerFET blew along with an associated double diode BAV23. Replaced both and works to some extent. This FET has plenty of drive 5V of pulses of repeat 3uS for the gate and about 3V ringing swing on the output to the first step up transformer. I assume that is as to be expected, never having the chance to see hot-side SMPS drive scope traces. But rectified output only climbs to about 1V of DC before the final stage (unreadable marking) thyristor discharges that supply into the second step up transformer, but of course not even enough to get a glow on a 110V neon. Doubling the C setting the 3uS pulses, to give longer repeat rate and that intermediary voltage rises to about 3V but still not enough for any proper final output. Adding more C and DC is then much less than 3V. What would people expect the intermediary DC to be? obviously higher than 12V battery supply Next stage would be disconnect the thyristor if that should be working but leaky and draining the intermediary DC but any other ideas? Would explain why the printing is very indistinct I suppose. DC ohms of the airgap type transformers are intermediary 0.1R//10.6R HV 0.3R//29R which seem reasonable, ie not major shorted turns if any
Reply to
N_Cook
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I would expect the output to be at fault when you take into consideration all the short circuits electric fencing can encounter.

Reply to
Meat Plow

corroded

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I've disconnected the HV section and no difference. The o/p of the intermediate is 4V pk-pk pulses with designed 3uS osc i/p. Barely enough to exceed the bank of 6 seriesed rectifier diodes . Inductances of the intermediate Tr are 0.1mH and 84mH . i'm wondering if there is shorted turns, will try and find some SMPS to try in reverse. The output Tr is E-I iron cored not HF on closer looking

Reply to
N_Cook

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Sounds like the unit may have been hit by a lightning surge. I have seen a few and usually all the electronic parts are blown as well at the transformer winding insulation punctured. To your question of intermediate voltage, I would suspect something in the 50-100V range. I imagine that there is a storage cap since your description sounds like a C-D circuit, so one would expect the intermediate voltage to be around 60% of the cap voltage rating, if it is an electrolytic. Neil S.

Reply to
nesesu

diode

never

neon.

Sounds like the unit may have been hit by a lightning surge. I have seen a few and usually all the electronic parts are blown as well at the transformer winding insulation punctured. To your question of intermediate voltage, I would suspect something in the 50-100V range. I imagine that there is a storage cap since your description sounds like a C-D circuit, so one would expect the intermediate voltage to be around 60% of the cap voltage rating, if it is an electrolytic. Neil S.

&&&&&&&

I'd not thought of that route, will desolder the C, script on the wrong side. I'd expect the dual monostable IC to be knocked out with lightning

Reply to
N_Cook

Would be nice to know the normal pulses of the driver circuit. It is possible a shorted device in the output could damage the driven stage.

Reply to
Meat Plow

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No manufacturer information aailable??

Reply to
hrhofmann

On Wed, 7 Jul 2010 14:46:36 +0100, "N_Cook" put finger to keyboard and composed:

B20 Dry Battery Energiser:

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If the above is your electric fence device, then the Stored Joules rating of 0.2J should enable you to calculate the voltage across the HV capacitor.

E = 1/2 x C x V^2

so V = sqrt (2 x 0.2 / C)

- Franc Zabkar

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Reply to
Franc Zabkar

The cap is 1uF , 280V ac rating. From the .5*C*V*V that comes to 630V, so something awry there. No more than 250V m 60% of likely DC rating, and I would have thought more like an equal split between 12V and 1800V so about 150V, transformers are much the same size if that is anything to go by

Reply to
N_Cook

If I ever get this thing working properly , how to check the average current drain? I am thinking 12V supply >- ammeter >- bank of 20V Cs summing to about 0.1F

Reply to
N_Cook

that is a current limited 12V supply , not a car battery of course

Reply to
N_Cook

On Thu, 8 Jul 2010 08:24:40 +0100, "N_Cook" put finger to keyboard and composed:

It may appear counterintuitive, but a rating of 280VAC/630VDC for a metallised polypropylene or polyester capacitor is not uncommon.

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See the Axial Metallized Polypropylene Capacitors on page 10 of the first PDF.

In particular, there is a 1uF, 280VAC/630VDC cap, p/n ARPM10563KYUKZZ.

- Franc Zabkar

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Reply to
Franc Zabkar

Find a cow, sheep or horse willing to test it.

Reply to
Meat Plow

current

0.1F

I don't think asking one "hoo moony mooliemoomps dooze this moozapper gizmoo take" would get very far

Reply to
N_Cook

On Thu, 8 Jul 2010 08:24:40 +0100, "N_Cook" put finger to keyboard and composed:

If the device is designed to output its rated energy over a 9V-12V supply range, then one would expect that the dump capacitor's voltage would be regulated. Otherwise the variation in the stored energy would be (12/9)^2 = 1.8X.

Is there any voltage feedback from the dump cap back to its charge controller? I'd expect to see a resistive potential divider feeding one input of an error amp (comparator?), and maybe a 5V or 2.5V reference on the other input. You may be able to compute the voltage from the resistance values.

- Franc Zabkar

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Reply to
Franc Zabkar

more

There is a chain of 3.3M resistors for feedback , I suspect it would change the 1.5KHz multivibrator rather than the 300KHz one. There is also the 1 to

2 second repetition cycling, perhaps 3 multivibrator package, also unreadable marking
Reply to
N_Cook

On Fri, 9 Jul 2010 08:45:56 +0100, "N_Cook" put finger to keyboard and composed:

I would expect that the multivibrator would have an internal reference voltage which it would compare against the voltage on the resistor at the bottom end of the potential divider. The IC's reference voltage may appear on one of its pins.

I would locate where the divider feeds into the IC, and determine the values of all the resistances in the chain. Then measure the voltages on the pins on either side of the feedback pin. If you can supply this information, then perhaps it will help ascertain the capacitor voltage.

- Franc Zabkar

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Reply to
Franc Zabkar

Hi,

I found this schematic (circuit diagram) somewhere on the net, is it anything like your one ?

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Ian.

Reply to
Ian French

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ectricfence.jpg

The 'IV' and HV stage is very similar, this one has a lot of SM so a bit more distributed for the higher voltages, ie tripling up of diodes and Rs

Do you have the URL of the text relating to that pic Search on that site just enigmatically/awkwardly/insultingly returns "The answer given for the random question was incorrect."

Reply to
N_Cook

Googled for it

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Reply to
N_Cook

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