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What type of capacitor should I use?



 
 
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  #11  
Old March 10th 17, 07:49 PM posted to rec.antiques.radio+phono,rec.audio.tubes,sci.electronics.repair
Tom Biasi
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Posts: 2
Default What type of capacitor should I use?

On 3/9/2017 9:17 PM, Foxs Mercantile wrote:
>
>
> Were you NOT paying attention previously when we ALL told
> you to use the yellow plastic caps? 630 volt.
>

Thanks for the reminder Jeff. I need some caps from Sal.:-)

Ads
  #12  
Old March 11th 17, 06:02 AM posted to rec.antiques.radio+phono,rec.audio.tubes,sci.electronics.repair
Jim Mueller
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Posts: 4
Default What type of capacitor should I use?

On Fri, 10 Mar 2017 18:04:32 +0000, analogdial wrote:

> Dan wrote:
>
>> Give this site a try.
>>
>> https://www.tedss.com/LearnMore/Amer...ade-Capacitors
>>
>>

> Right on the first page:
>
> "Think all capacitors made in the Far East are cheap, noisy, low
> quality."
>
> 'If you are looking for quality components, then TEDSS.com is for YOU.'
>
> "Americans put a man on the moon in 1969 with American-made capacitors.
> The greatest military power in the world was made by using High Quality
> American Made apacitors."
>
>
> Wow. I suppose the grammar and spelling are about what you'd expect
> from a Usenet loon, but subpar for a vendor trying to sell quality.
>
> And, for what it's worth, I DON'T think ALL capacitors made in the Far
> East are cheap, noisy, low quality. And as soon as I hear that the
> Chinese have mastered the art of making "High Quality apacitors.", I'll
> be doubling up on my Mandarin lessons.



And if you look at their listings, the capacitors are made by a mix of
manufacturers, some that I've heard of, some not. It appears that they
are a surplus house.

--
Jim Mueller

To get my real email address, replace wrongname with dadoheadman.
Then replace nospam with fastmail. Lastly, replace com with us.
  #14  
Old August 9th 17, 07:50 PM posted to rec.antiques.radio+phono,rec.audio.tubes,sci.electronics.repair
Michael A. Terrell
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Posts: 318
Default What type of capacitor should I use?

Big Bad Bob wrote:
> On 03/09/17 17:01, wrote:
>> What type of capacitor would be the best match to replace the old
>> paper/wax caps in old tube gear?
>>
>> I am not referring to the electrolytics, those I know need to be
>> electrolytic caps. I am referring to the inter stage caps, such as
>> .01 .05 .1, .005 and so on.....
>>
>> The object is to replace all the caps in an old tube radio, or any
>> other tube stuff.

>
> well, if you must replace them with more modern components, a decent
> ceramic capacitor should do fine. From what I have seen, ceramics
> were common in gear made in the 50's and 60's because of their small
> relative size and reasonable consistency in manufacturing.
>
> You should be able to order them from companies like Digikey, Mouser,
> etc.. Just make sure the voltage ratings are high enough, and you
> should be ok.
>
> I've seen on-line "photo piles" of before/after restoration efforts in
> which modern components were "hidden" inside of hollowed-out
> components. Maybe you can stash a modern ceramic inside of the
> paper/wax tube, and seal it up with a bit of hot glue...



Ceramic capacitors are mostly cheap crap. Some have a wide change in
capacitance, at different voltages. Some are microphonic, and their
normal failure mode is a dead short. About the only place they should be
used are for DC bybass, or in low power tuned circuits.


--
Never **** off an Engineer!

They don't get mad.

They don't get even.

They go for over unity! ;-)
  #15  
Old August 10th 17, 03:47 AM posted to rec.antiques.radio+phono,rec.audio.tubes,sci.electronics.repair
Jim Mueller
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Posts: 4
Default What type of capacitor should I use?

On Wed, 09 Aug 2017 04:54:25 -0700, Big Bad Bob wrote:

> On 03/09/17 17:01, wrote:
>> What type of capacitor would be the best match to replace the old
>> paper/wax caps in old tube gear?
>>
>> I am not referring to the electrolytics, those I know need to be
>> electrolytic caps. I am referring to the inter stage caps, such as .01
>> .05 .1, .005 and so on.....
>>
>> The object is to replace all the caps in an old tube radio, or any
>> other tube stuff.

>
> well, if you must replace them with more modern components, a decent
> ceramic capacitor should do fine. From what I have seen, ceramics were
> common in gear made in the 50's and 60's because of their small relative
> size and reasonable consistency in manufacturing.
>
> You should be able to order them from companies like Digikey, Mouser,
> etc.. Just make sure the voltage ratings are high enough, and you
> should be ok.
>
> I've seen on-line "photo piles" of before/after restoration efforts in
> which modern components were "hidden" inside of hollowed-out components.
> Maybe you can stash a modern ceramic inside of the paper/wax tube, and
> seal it up with a bit of hot glue...


It will be tough to find good ceramics in the values listed with voltage
ratings high enough for tube gear. Polyester (Mylar) or Polypropylene
are better choices.

As for the quality of ceramic capacitors, it depends on what kind of
ceramic is used. C0G ceramics are about the best capacitors you can
easily get. They are very stable, have very low loss, and are excellent
in just about every other way. The one way they are not excellent is
that, except for low values (less than around 1000pF - depends on
manufacturer) they are large and expensive. Mid grade ceramics like X7R
are less stable and less expensive. They are suitable for most audio
frequency work. The really bad ceramics are the ones like Z5U. They are
truly horrible in most ways and are suitable only for non-critical
circuits like supply bypassing. They are, however, tiny and very cheap.
Go to the manufacturer's data sheet for the capacitors you want to use to
see if their characteristics match the application.



--
Jim Mueller


To get my real email address, replace wrongname with eggmen.
Then replace nospam with expressmail. Lastly, replace com with dk.
  #16  
Old August 16th 17, 04:14 AM posted to rec.antiques.radio+phono,rec.audio.tubes,sci.electronics.repair
Big Bad Bob
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Posts: 320
Default What type of capacitor should I use?

On 08/09/17 19:47, Jim Mueller wrote:
> Go to the manufacturer's data sheet for the capacitors you want to use to
> see if their characteristics match the application.


ack on that. it's always good advice to see the data sheet.

Somewhat recently, I bought some 500V 0.047uF ceramics that I use for
high freq bypass in a 400V power supply. I checked, it's X7R. no
problems noted. (got them from digikey along with others)

but yeah, the part selectors don't give you a whole lot of choice for
capacitors at voltages about 100V, sometimes. Still, I've never had a
problem with what I've purchased that way.


--
your story is so touching, but it sounds just like a lie
"Straighten up and fly right"
  #17  
Old August 16th 17, 04:20 AM posted to rec.antiques.radio+phono,rec.audio.tubes,sci.electronics.repair
Big Bad Bob
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Posts: 320
Default What type of capacitor should I use?

On 03/10/17 02:04, wrote:
> Not much of anything made in China is a quality item


actually, I'd think that you just have to be careful and pick a
reputable manufacturer.


--
your story is so touching, but it sounds just like a lie
"Straighten up and fly right"
  #18  
Old August 16th 17, 04:21 AM posted to rec.antiques.radio+phono,rec.audio.tubes,sci.electronics.repair
Big Bad Bob
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Posts: 320
Default What type of capacitor should I use?

On 03/10/17 05:34, Foxs Mercantile wrote:
> There's that magic word "feelings" again. Based on nothing.


yeah, 'Feel' the 'F' word. so many bad decisions are made in the name
of 'Feel'.

  #19  
Old August 16th 17, 04:24 AM posted to rec.antiques.radio+phono,rec.audio.tubes,sci.electronics.repair
Big Bad Bob
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Posts: 320
Default What type of capacitor should I use?

On 08/09/17 19:47, Jim Mueller wrote:
> It will be tough to find good ceramics in the values listed with voltage
> ratings high enough for tube gear. Polyester (Mylar) or Polypropylene
> are better choices.


that might be in a lot of cases. I haven't had that much trouble, but
price DOES go up rather fast as the rated voltage increases. I'll
consider mylar/poly capacitors also, test, see what happens.

  #20  
Old August 16th 17, 06:53 AM posted to rec.antiques.radio+phono,rec.audio.tubes,sci.electronics.repair
rickman
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Posts: 22
Default What type of capacitor should I use?

Big Bad Bob wrote on 8/15/2017 11:21 PM:
> On 03/10/17 05:34, Foxs Mercantile wrote:
>> There's that magic word "feelings" again. Based on nothing.

>
> yeah, 'Feel' the 'F' word. so many bad decisions are made in the name of
> 'Feel'.


Once you learn about human reasoning you will find it *always* comes down to
feelings. You may have conditioned yourself to weight your feelings on
"logic", but it still comes down to feelings and we have ways of working
around the logic when we want to.

As you say, too often we take a bypass based on some limited experience or
even anecdote we've heard that gives us a "feeling" with little rational
process behind it. See a couple of bad capacitors from any given company or
category of supplier and a strong bias develops which works to bypass that
source.

--

Rick C
 




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