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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

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Old 20th Jun 2017, 11:51 am   #1
TonyDuell
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Default Old paper capacitors -- any use?

Is there any use for the paper capacitors in cuboidal (rectangular if you are not a pedant...) metal cans? Made by Hunts, Dubilier, etc. I assume they are all leaky by now, but I wonder if people want them to re-stuff.

I've come across a few when sorting things out here and wonder if I should throw them out, offer them here, or keep them.
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Old 20th Jun 2017, 12:11 pm   #2
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Default Re: Old paper capacitors -- any use?

I think you might find some one would love them. If only to re stuff and make something look more original if a too modern replacement is fitted. I certainly keep one or two.

The old story, as soon as they are dumped they are needed!
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Old 20th Jun 2017, 12:58 pm   #3
G8HQP Dave
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Default Re: Old paper capacitors -- any use?

I have two of those. When I get a round tuit I will offer them on here or elsewhere. Mine are new in box.

Some of these caps may contain PCBs, so those ones would not be suitable for restuffing.
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Old 20th Jun 2017, 1:15 pm   #4
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Default Re: Old paper capacitors -- any use?

Quote:
Originally Posted by TonyDuell View Post
I've come across a few when sorting things out here and wonder if I should throw them out, offer them here, or keep them.
Check them leakage. As others have said they could always be stuffed if they aren't any good as capacitors.

Much better than having to create one from scratch.

Peter
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Old 20th Jun 2017, 4:02 pm   #5
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Default Re: Old paper capacitors -- any use?

If you mean the oiled filled metal can type with terminals on ceramic pillars, these seem to last much better than other paper dielectric capacitors. As others have said, check for leakage and value, preferably near working voltage, and use if OK. I still have a home-built variable PSU with an 8uF, 600V paper capacitor as the reservoir cap, and it's fine.
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Old 20th Jun 2017, 4:26 pm   #6
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Default Re: Old paper capacitors -- any use?

In decoupling applications, I find many vintage paper capacitors are still good enough, with leakage resistance a couple of orders of magnitude higher than relevant circuit resistance values. Originality (and laziness ) then wins out over any minor change in circuit performance. But then I'm of the generation that regarded Hunts Moldseal as a modern high quality capacitor.

The exception, of course is in the well-recognised anode/grid coupling applications where replacement is usually necessary.

Martin
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Old 20th Jun 2017, 6:35 pm   #7
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Default Re: Old paper capacitors -- any use?

The ones in large rectangular metal cans with two screw terminals or solder tags on insulators on the top seem to survive much better than the common-or-garden waxy types (even Hunts Moldseals ). I've got quite a number of roughly WWII-era ones which show no leakage on a Megger and still have the correct capacitance.

Don't throw them out without checking them first - you may well be pleasantly surprised.

Chris
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Old 20th Jun 2017, 7:34 pm   #8
TonyDuell
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Default Re: Old paper capacitors -- any use?

I have no real use for them, so when I have sorted out what I have, I will probably offer them here. So far I've found (at least) an 8uF 1000V one and a 33uF 2.5kV one (for photographic flash applications (!)).

As regards them containing PCBs, that may mean I can't sent them by post. None are leaking oil though. And a friend of mine who works with national-grid type transformers, etc gave me some (IMHO wise) advice :

'If you work every day up to your elbows in PCB transformer oil it will do you harm. But the amount found in one capacitor of the size you work with is pretty much harmless unless you do something very silly with it'
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Old 20th Jun 2017, 8:24 pm   #9
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Smile Re: Old paper capacitors -- any use?

Hi,
I have quite a few old paper caps which I am loathe to chuck out if anyone can use them. I was thinking of offering them on the forum, but thought no one would want them.
Cheers, Pete.
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Old 21st Jun 2017, 5:20 am   #10
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Default Re: Old paper capacitors -- any use?

I've "reformed" ( IE leakage went down after time on a HV source) a few of these ok. Not sure if that's correct but it seemed to work. I've used them as they're handy for HV applications where you need a few micro farads at 600 odd volts. You find them in HP distortion meters happily chugging away and in quite a few scopes.

I also have some 1u 630v Dublier NOS cylindrical paper caps still in their polythene wrapping that after some time on a cap reformer are handy for use in power supply's.

I'll happily take them off your hands Tony, especially the 8u 1000v and 33u 2.5kv - very useful.

Andy.
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Old 22nd Jun 2017, 12:19 pm   #11
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Default Re: Old paper capacitors -- any use?

Will we see a diabolical artifact incorporating them anytime soon?
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Old 23rd Jun 2017, 5:15 am   #12
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Default Re: Old paper capacitors -- any use?

Most assuredly. Have a hankering to play with some 813's.

A.
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Old 23rd Jun 2017, 2:49 pm   #13
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Default Re: Old paper capacitors -- any use?

RF or big audio?
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Old 24th Jun 2017, 12:58 pm   #14
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Default Re: Old paper capacitors -- any use?

I have a couple of Ducon paper and oil caps that I cannot bear to chuck out. They both measure within a few percent and tested with rated voltage, although one has written on it- "Has oil leak. Replaced 25/10/51..." and some more non-readable text. It actually shows no signs of holes, splits or external oil. The other one has a liquid sound when shaken but the 'leaked' one does not. They will sit on the shack window sill until the end I suspect.
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