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Forums
4hv.org :: Forums :: High Voltage
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Capacitive Voltage divider, for O-scopes (10,000:1)

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Proud Mary
Sun Sept 12 2010, 03:55AM
Proud Mary Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
Patrick wrote ...

The X and Y caps from ATX power supplies are in the 1, 2, 3 and 4 nF range. These or Proud Mary's silver caps may be needed, Pakastan flood donation done Proud Mary.

If you want to send me your mailing address in a PM, I'll post the parts to you by airmail on Monday morning.
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Patrick
Sun Sept 12 2010, 05:55AM
Patrick Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
Proud Mary wrote ...

Patrick wrote ...

The X and Y caps from ATX power supplies are in the 1, 2, 3 and 4 nF range. These or Proud Mary's silver caps may be needed, Pakastan flood donation done Proud Mary.

If you want to send me your mailing address in a PM, I'll post the parts to you by airmail on Monday morning.

yeah ok, will PM you tomarrow. also i think i need a potential transformer, for calibration.
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Proud Mary
Fri Sept 17 2010, 02:52PM
Proud Mary Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
 		I have this afternoon posted by airmail:

2 x 2000pF 2% 500V silver mica
2 x 2000pF 5% 350V silver mica
2 x 50pF 0.5% 350V silver mica
2 x 68pF vane-type air trimmer ceramic/silver plate screwdriver slot adjust

I didn't think I had any 2nF silver micas, but found some on a shelf I seldom visit.

I measured Cmin on the trimmers with the vanes fully out, and it came to 1.5pF at 200kHz after I deducted 0.3pF strays.

I have sent two of each - and two different sorts of 2nF - to give you room for making a mistake.

I have sent the parts by ordinary airmail, and think you will receive them in ten days or so.
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Patrick
Fri Sept 17 2010, 03:29PM
Patrick Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
 		TY ! cheesey
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Patrick
Mon Sept 27 2010, 01:16AM
Patrick Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
 		OK Proud Mary, I got your package, those variable caps are nice little marvels, Thanks so much this helps me so much.
1285550203 2431 FT91689 Proudmarycaps
caps and my Graphite Ipod.

on a realated note, how do i get that one trimmer cap, to rotate, it wont. is there a special trick?

ALSO, stay tuned folks, ill be updating this thread in the next few days or a week.
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Proud Mary
Mon Sept 27 2010, 02:59AM
Proud Mary Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
Patrick wrote ...

OK Proud Mary, I got your package, those variable caps are nice little marvels, Thanks so much this helps me so much.
1285550203 2431 FT91689 Proudmarycaps
caps and my Graphite Ipod.

on a realated note, how do i get that one trimmer cap, to rotate, it wont. is there a special trick?

ALSO, stay tuned folks, ill be updating this thread in the next few days or a week.

They are intentionally stiff, to stop them rotating with vibration, but it should just turn with a screwdriver.
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Patrick
Mon Sept 27 2010, 03:51AM
Patrick Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
 		As for the trimmer caps, one of them turns easy, the other was very hard to turn, but both work now.

here is my insulator, i just got it back from my clay making place.
1285559464 2431 FT91689 Red Shiver
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IntraWinding
Mon Sept 27 2010, 06:55AM
IntraWinding Registered Member #2261 Joined: Mon Aug 03 2009, 01:19AM
Location: London, UK
Posts: 581
 		Nicely made insulator smile
Just a thought: have you checked it at working voltage just in case the glaze conducts?
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Patrick
Mon Sept 27 2010, 07:11AM
Patrick Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
IntraWinding wrote ...

Nicely made insulator smile
Just a thought: have you checked it at working voltage just in case the glaze conducts?
how would you recommend i do so?
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Proud Mary
Mon Sept 27 2010, 08:38AM
Proud Mary Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
Patrick wrote ...

IntraWinding wrote ...

Nicely made insulator smile
Just a thought: have you checked it at working voltage just in case the glaze conducts?
how would you recommend i do so?


Put it in a microwave oven.

Crockery with conductive glazes start crazing, crackling, and heating almost immediately when put into a microwave oven by mistake. If your insulator is still cold after a minute or so, I would think it safe to say that it is not significantly conductive.
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