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From: Franc Zabkar on 7 Jul 2010 18:10
On Wed, 7 Jul 2010 14:46:36 +0100, "N_Cook" <diverse(a)tcp.co.uk> put
finger to keyboard and composed:

>What would people expect the intermediary DC to be? obviously higher than
>12V battery supply

B20 Dry Battery Energiser:
http://www.forcefield-uk.co.uk/b20.htm

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
--
Please remove one 'i' from my address when replying by email.
From: N_Cook on 8 Jul 2010 03:24
Franc Zabkar <fzabkar(a)iinternode.on.net> wrote in message
news:e8u936t7msgm25002ne31halc1par3u74h(a)4ax.com...
> On Wed, 7 Jul 2010 14:46:36 +0100, "N_Cook" <diverse(a)tcp.co.uk> put
> finger to keyboard and composed:
>
> >What would people expect the intermediary DC to be? obviously higher than
> >12V battery supply
>
> B20 Dry Battery Energiser:
> http://www.forcefield-uk.co.uk/b20.htm
>
> 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
> --
> Please remove one 'i' from my address when replying by email.

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


From: N_Cook on 8 Jul 2010 03:54
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
>- fencer unit


From: N_Cook on 8 Jul 2010 04:01
that is a current limited 12V supply , not a car battery of course



From: Franc Zabkar on 8 Jul 2010 05:33
On Thu, 8 Jul 2010 08:24:40 +0100, "N_Cook" <diverse(a)tcp.co.uk> put
finger to keyboard and composed:

>Franc Zabkar <fzabkar(a)iinternode.on.net> wrote in message
>news:e8u936t7msgm25002ne31halc1par3u74h(a)4ax.com...
>> On Wed, 7 Jul 2010 14:46:36 +0100, "N_Cook" <diverse(a)tcp.co.uk> put
>> finger to keyboard and composed:
>>
>> >What would people expect the intermediary DC to be? obviously higher than
>> >12V battery supply
>>
>> B20 Dry Battery Energiser:
>> http://www.forcefield-uk.co.uk/b20.htm
>>
>> 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)

>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

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

http://www.aerovox.com/pdf/DC_Film_Axials.pdf
http://www.ibselectronics.com/pdf/pa/wima/wima_pulse_capacitors.pdf
http://www.descartes.com.tw/product/wima/wima_pdf/WIMA_MKP_4.pdf

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
--
Please remove one 'i' from my address when replying by email.
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