# Source for polystyrene Cap

#### Hypatia's Protege

Joined Mar 1, 2015
3,226
Kind Friends

Pursuant to a restoration project, the TS of THIS THREAD (relevant post =#216) requires a thru-hole PS capacitor Speced at: 1.5nF @125V (5% Tolerance)...

The major supply houses/distributors (e.g. Mouser/Digikey, etc...) have little to nothing to choose from in PS -- My next best choice (PPS) likewise 'struck out' --- Not being especially au fait with contemporary capacitor technology, I am requesting information in regards to a readily sourceable product meeting the above cited specifications and exhibiting a degree of thermal stability commensurate with that of PS...

FWIW -- As per their component numbering system, Xicon's 13PW215K is an exact replacement -- howbeit I can find no distributor dealing in said component...

Best regards
HP

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#### ian field

Joined Oct 27, 2012
6,539
Kind Friends

Pursuant to a restoration project, the TS of THIS THREAD requires a thru-hole PS capacitor Speced at: 1.5nF @125V (5% Tolerance)...

The major supply houses/distributors (e.g. Mouser/Digikey, etc...) have little to nothing to choose from in PS -- My next best choice (PPS) likewise 'struck out' --- Not being especially au fait with contemporary capacitor technology I am requesting information in regards to a readily a sourceable product meeting the above cited specifications and exhibiting a degree of thermal stability commensurate with that of PS...

FWIW -- As per their component numbering system Xicon's 13PW215K is an exact replacement -- howbeit I can find no distributor dealing in said component...

Best regards
HP
Years ago I read somewhere that the tempco of polystyrene caps was well matched to pot core tuned circuits.

For anything else it might be worth looking whether silver mica types can still be had.

Failing that - I'd examine the specs for tubular ceramic to see if that can be got away with.

#### Hypatia's Protege

Joined Mar 1, 2015
3,226
Years ago I read somewhere that the tempco of polystyrene caps was well matched to pot core tuned circuits.

For anything else it might be worth looking whether silver mica types can still be had.

Failing that - I'd examine the specs for tubular ceramic to see if that can be got away with.
The TS' App is to a CRO's horz deflection circuitry -- hence anything exhibiting decent temp stability would likely fit the bill --- SM would be great if the physical dimensions of a 1500pf device can be accommodated! Ditto for a TC exhibiting a zero temp coefficient

---EDIT---
Disambiguation:
In the above:
SM= Silver Mica
TC= Tubular Ceramic

Best regards
HP

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#### #12

Joined Nov 30, 2010
18,210

#### jpanhalt

Joined Jan 18, 2008
10,068
What form factor for SM is acceptable? More important, will NPO/COG ceramic suffice? If so, there are lots of choices that are relatively inexpensive.

http://www.digikey.com/product-search/en/capacitors/ceramic-capacitors/131083?k=ceramic+NPO&pv13=88&FV=38000e,380012,38002e,fff40002,fff8000b,c0002&mnonly=0&newproducts=0&ColumnSort=0&page=1&quantity=0&ptm=0&fid=0&pageSize=500

Within the past year or so, I searched for a PS capacitor for an oscillator I made just 10 years ago. As you observed, they are now none existent.

John

#### Hypatia's Protege

Joined Mar 1, 2015
3,226
What form factor for SM is acceptable?
Ideally axial, realistically radial, necessarily through-hole

will NPO/COG ceramic suffice?
NPO/COG (i.e. 'zero' temperature coefficient), Yes! -- Ceramic, only as a last resort!

Within the past year or so, I searched for a PS capacitor for an oscillator I made just 10 years ago. As you observed, they are now none existent.
Hence my policy of ≈10X the anticipated worst-case requirement --- I call it maintainability -- some call it 'better living through OCD'!

By way of demonstration of what might otherwise be taken as hyperbole -- below is a 'random' handful from my garret-lab's NOS PP Cap stores:

With syllogomanic regards
HP

#12

#### shortbus

Joined Sep 30, 2009
7,840
syllogomanic
Wow!! A new word for my condition! My wife and kids call me a "hoarder", I call myself a "packrat", now I can be known as a "syllogomaniac". Makes it sound important.

#### GopherT

Joined Nov 23, 2012
8,012
Wow!! A new word for my condition! My wife and kids call me a "hoarder", I call myself a "packrat", now I can be known as a "syllogomaniac". Makes it sound important.
The first time I read @Hypatia's Protege 's post, I assume from the context that it meant, "there's a 1.5nF +/-5% 125V PS capacitor in there somewhere."

I apparently have the same condition. Fortunately, mine are slightly organized. Unfortunately, I only have a 1.2nF part that the OP would be welcome to.

#### ian field

Joined Oct 27, 2012
6,539
What form factor for SM is acceptable? More important, will NPO/COG ceramic suffice? If so, there are lots of choices that are relatively inexpensive.

http://www.digikey.com/product-search/en/capacitors/ceramic-capacitors/131083?k=ceramic+NPO&pv13=88&FV=38000e,380012,38002e,fff40002,fff8000b,c0002&mnonly=0&newproducts=0&ColumnSort=0&page=1&quantity=0&ptm=0&fid=0&pageSize=500

Within the past year or so, I searched for a PS capacitor for an oscillator I made just 10 years ago. As you observed, they are now none existent.

John
You have to be careful when putting ceramic types in flyback circuits, ceramics of all types gained notoriety in TV flybacks - maybe its less harsh in a scope.

In most cases ceramics are lossy at high frequency - it makes them an excellent choice for supply decoupling. They tend to dissipate fast spikes rather than resonating with parasitic inductances.

With the most common uses for ceramic, tempco is way down the list, some also vary with applied voltage.

There are certain types of ceramic capacitor specifically for RF tuning circuits - NPO is probably one of them.

#### #12

Joined Nov 30, 2010
18,210
I apparently have the same condition. Fortunately, mine are slightly organized.
I'm rather famous for being organized. "A part you can't find is just as good as a part you don't have."
or, "I have one of everything that Dennis has two of. The difference is that I can find mine!"

#### jpanhalt

Joined Jan 18, 2008
10,068
I'll bet you didn't Google it!

Singapore RS has them: axial, 1500 PF @SGD 23.80/10 :http://sg.rs-online.com/web/p/polystyrene-film-capacitors/0113336/

As for my misunderstanding that SM = surface mount in this comment, "SM would be great if the physical dimensions...", such abbreviations are frequently ambiguous. I was just not familiar with horizontal deflection circuits.

John

#### GopherT

Joined Nov 23, 2012
8,012
I'll bet you didn't Google it!

Singapore RS has them: axial, 1500 PF @SGD 23.80/10 :http://sg.rs-online.com/web/p/polystyrene-film-capacitors/0113336/

As for my misunderstanding that SM = surface mount in this comment, "SM would be great if the physical dimensions...", such abbreviations are frequently ambiguous. I was just not familiar with horizontal deflection circuits.

John
$17 USD plus shipping from Singapore - and the joy of storing 9 of the 10 units received. That's no fun. Note, RS requires a minimum order of 10 pieces. #### jpanhalt Joined Jan 18, 2008 10,068$17 USD plus shipping from Singapore - and the joy of storing 9 of the 10 units received. That's no fun.

Note, RS requires a minimum order of 10 pieces.
No fun? WTH. Keep one for yourself and sell the remaining 8 on eBay for $7.68 each with free S&H. That is a lot better interest than you get from your bank. Or, am I assuming too much? As for the 10-piece minimum, that was already included in the cost I gave. John #### Tesla23 Joined May 10, 2009 406 Kind Friends Pursuant to a restoration project, the TS of THIS THREAD (relevant post =#216) requires a thru-hole PS capacitor Speced at: 1.5nF @125V (5% Tolerance)... The major supply houses/distributors (e.g. Mouser/Digikey, etc...) have little to nothing to choose from in PS -- My next best choice (PPS) likewise 'struck out' --- Not being especially au fait with contemporary capacitor technology, I am requesting information in regards to a readily a sourceable product meeting the above cited specifications and exhibiting a degree of thermal stability commensurate with that of PS... FWIW -- As per their component numbering system, Xicon's 13PW215K is an exact replacement -- howbeit I can find no distributor dealing in said component... Many advance thanks!!! Best regards HP this? http://www.newark.com/lcr-components/fscex-1500pf-1-160v/film-capacitor-fsc-ex-series-1500/dp/97K0254?ost=9520465&selectedCategoryId=&categoryName=All+Categories&categoryNameResp=All+Categories #### MrChips Joined Oct 2, 2009 21,634 This what you're looking for? Markings: SUFLEX 1500pF ±5% 125VDC YF I have only one, never used. Send me PM if interested. #### GopherT Joined Nov 23, 2012 8,012 No fun? WTH. Keep one for yourself and sell the remaining 8 on eBay for$7.68 each with free S&H. That is a lot better interest than you get from your bank. Or, am I assuming too much?
As for the 10-piece minimum, that was already included in the cost I gave.
John
If you have the time and packaging material, set up a business. Again, you pick an unsustainable business. In this case, poor pricing will leave you stuck with that inventory until the end of time. Remember, eBay takes a cut and PayPal takes a cut and you offered to pay postage.

Good luck though.

http://www.ebay.com/sch/i.html?_odkw=(ps,+polystyrene,+styrene)+(1.5nF,+1500pf,+0.0015uF,+152)+(cap,+capacitor,+caps,+capacitors)&_sop=16&_sac=1&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0.H0.X(ps,+polystyrene,+styroflex)+(1.5nF,+1500pf,+0.0015uF,+152)+(cap,+capacitor,+ca.TRS0&_nkw=(ps,+polystyrene,+styroflex)+(1.5nF,+1500pf,+0.0015uF,+152)+(cap,+capacitor,+caps,+capacitors)&_sacat=0

#### RichardO

Joined May 4, 2013
2,271
I have a lot of caps that look just like these! Unfortunately they are all have a 100 volt (not 125v) rating.

#### Hypatia's Protege

Joined Mar 1, 2015
3,226
As for my misunderstanding that SM = surface mount in this comment, "SM would be great if the physical dimensions...",
Indeed, my intention was Silver Mica -- If i'm not careful the Web will make an SMSer of me yet!

such abbreviations are frequently ambiguous.
No worries... Considering the abbreviation in question - It could have gone worse

Best regards
HP

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#### Hypatia's Protege

Joined Mar 1, 2015
3,226
and the joy of storing 9 of the 10 units received.
Surplus is always a good thing!

Best regards
HP