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Thread: Glass capacitor

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    Glass capacitor

    I'm working on a vintage organ and it has glass capacitors. I am not sure if I'm reading the value right. This one has 200 on it and the tolerance below. What is the value of this capacitor?

    Thanks.
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    Supporting Member Jazz P Bass's Avatar
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    Looks like a diode to me.

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    A diode wouldn't have a tolerance right? I'm pretty sure it's a vintage glass cap.

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    Glass? Looks like polystyrene to me

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    Quote Originally Posted by frus View Post
    Glass? Looks like polystyrene to me
    Polystyrene gets my vote too. Sometimes they fail with age, sort of prematurely. They were a bugaboo in Klark-Teknik graphic EQ's. I'm guessing yours is 200 pF. Typically the voltage spec is on the low side, 63V is common. They're also sensitive to being overheated when leads are soldered.

    Likely any competent 200 or 220 pF cap will work as a replacement if yours is bad.

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    Thank you Leo_Gnardo!

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    Looks like a 200pF/160V polystyrene ("Styroflex") capacitor. The red band denotes the voltage rating (160VDC).
    These are high quality/precision caps often found in oscillator circuits. They rarely fail but typically don't stand temperatures above 70°C.

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    Last edited by Helmholtz; 07-25-2019 at 03:28 PM.
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    Old Timer Leo_Gnardo's Avatar
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    Quote Originally Posted by Helmholtz View Post
    Looks like a 200pF/160V polystyrene ("Styroflex") capacitor. The red band denotes the voltage rating (160VDC).
    These are high quality/precision caps often found in oscillator circuits. They rarely fail but typically don't stand temperatures above 70°C.
    That's good to know, thanks Helmholtz! Maybe K-T bought a dodgy batch way back in the 80's.

    If the suspect cap is part of an oscillator it may be best to stick with polystyrene.

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    If the suspect cap is part of an oscillator it may be best to stick with polystyrene.
    ...and match the cap value as it may determine oscillator frequency.

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    Quote Originally Posted by Helmholtz View Post
    Looks like a 200pF/160V polystyrene ("Styroflex") capacitor. The red band denotes the voltage rating (160VDC).
    These are high quality/precision caps often found in oscillator circuits. They rarely fail but typically don't stand temperatures above 70°C.
    Thank you Helmholtz. The lead broke off the one I'm replacing so it most likely didn't fail.

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    Îf the circuit requires 200pF, you may wire a 220pF in series with a 2.2nF cap.

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    Old Timer J M Fahey's Avatar
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    +1 vote for styroflex.

    We had a local factory of very high quality Mallory Styroflex caps , so good that the main Moog oscillator one was an Argentine made one ... I guess they had closed the USA plant and sourced those made here, "the old way".

    Then Reaganomics hit us and we lost all of our Electronics Industry and the little which survives, is run by stubborn greybeards like me who donīt know anything else so canīt switch to, say, coding (as was suggested to US coal miners ).

    Of course, in, say, 20 years tops, even these little resistance pockets will also disappear.

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    Juan Manuel Fahey

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    Quote Originally Posted by J M Fahey View Post
    Then Reaganomics hit us and we lost all of our Electronics Industry and the little which survives, is run by stubborn greybeards like me who donīt know anything else so canīt switch to, say, coding (as was suggested to US coal miners ).
    Or... those coal miners could become endive farmers. Yeh, that always works! Big market going unfilled for endives. Plus, it's best to give endives a spell in the dark before harvest, coal miners definitely have an advantage there.


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    Senior Member nevetslab's Avatar
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    With the value of 200 on the polystyrene cap, that could well be 20pF, where 201 would 200pF, 202 being 2nF and so on. I've been burned by those assumptions before, thinking it was 200pF.

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    Quote Originally Posted by nevetslab View Post
    With the value of 200 on the polystyrene cap, that could well be 20pF, where 201 would 200pF, 202 being 2nF and so on. I've been burned by those assumptions before, thinking it was 200pF.
    I have an assortment of Styroflex caps from the 80s (as well as databooks). Those were/are all labelled in plain pF values.

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    On glass caps, real ones, for the record Peavey used them in some late 70's - 80's amps. Little guys that looked like diodes. They fit an unexpected amount of capacitance in a tiny package, the tradeoff being rated at low voltage. Definitely not electrolytic, I take it they were some kind of thin film technology. There were also caps in glass cylinders, film in oil, from the 1950's - early 60's. I have one, it's a work of art. About 1.5 inches long, half an inch wide cylinder. But I don't think I wanna know what kind of oil is in there - could well be polychlorinated biphenyl or some similar poison.

    Back to the program already in progress...

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    Quote Originally Posted by Helmholtz View Post
    I have an assortment of Styroflex caps from the 80s (as well as databooks). Those were/are all labelled in plain pF values.
    I love polystyrene capacitors. Unfortunately, they have 3 main disadvantages. First, like you mentioned, they can be damaged at relatively low heat. Second, they are often terminated with very light gauge lead wire (but not always). Lastly, manufacture of capacitor grade polystyrene largely ceased in 2012. So, much like polycarbonate, small runs of new production rely on stores of warehouse stock.

    Plus, just between all of us,... I like the way they sound
    But you'll never get me to admit it.

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    Me too - LCR Components in Wales UK are a small UK manufacturer, I've been buying their 630V low pF polystyrene caps for decades, excellent spec, they're distributed by Farnell so I guess that Newark should carry them in North America.
    The 630V range have nice sturdy leads
    A company I used to work for needed a 0.33uF 50V high spec cap, LCR made a small custom batch (polycarb I think) at a very reasonable cost.
    http://www.farnell.com/datasheets/17...790.1537990594

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    Last edited by pdf64; 07-26-2019 at 12:26 PM.

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    Senior Member SoulFetish's Avatar
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    Quote Originally Posted by pdf64 View Post
    Me too - LCR Components in Wales UK are a small UK manufacturer, I've been buying their 630V low pF polystyrene caps for decades, excellent spec, they're distributed by Farnell so I guess that Newark should carry them in North America.
    The 630V range have nice sturdy leads
    A company I used to work for needed a 0.33uF 50V high spec cap, LCR made a small custom batch (polycarb I think) at a very reasonable cost.
    http://www.farnell.com/datasheets/17...790.1537990594
    Newark was acquired by Avenet recently, but It looks they still are partnered with Farnell for inventory and distribution for now.
    47-720pF @ 630V is pretty sweet. I could use those all day

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    Some Styroflex caps demonstrating that even large nF values were labelled with pF numbers. An additional letter specifies cap tolerance. The huge 0.1ĩ one is probably a prototype or a special order sample:

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    Last edited by Helmholtz; 07-26-2019 at 02:55 PM.
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    Senior Member nevetslab's Avatar
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    Quote Originally Posted by Helmholtz View Post
    Some Styroflex caps demonstrating that even large nF values were labelled with pF numbers. An additional letter specifies cap tolerance. The huge 0.1ĩ one is probably a prototype or a special order sample:

    Click image for larger version. 

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    Now THAT ^^^^ is my idea of a proper capacitor!!

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    I only dig this thread up because I had a question about identifying voltage rating. I have some ranging from 100pF-1000pF.

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    Helmholtz, do you know if the markings hold true across all manufactures? Do you know what the voltage rating is on these?

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    Old Timer tedmich's Avatar
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    I put polystyrene caps in my headphone amp, and ironically I recently listened to this vocalist
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    also Poly Styrene (RIP)
    their best song
    https://www.youtube.com/watch?v=xjVVhJ-INWQ
    lots of polymers therein

    on the caps those leads are incredibly weak, I think tinned copper

    here's a nice breakdown of different PS caps.
    https://www.tedss.com/LearnMore/Poly...ilm-Capacitors
    (also a Ted)

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    Senior Member SoulFetish's Avatar
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    Quote Originally Posted by tedmich View Post
    on the caps those leads are incredibly weak, I think tinned copper
    Fortunately the most of the ones in I have (some in that photo) have nice heavier gauge leads than some of the other common polystyrene types. I wanna say, like, 20AWG or there abouts

    Edit: just checked out that tedss link. Just what I was looking for

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    Helmholtz, do you know if the markings hold true across all manufactures? Do you know what the voltage rating is on these?
    German manufacturers used:

    blue: 25VDC
    yellow: 63VDC
    red: 160VDC
    green: 250VDC
    brown: 400VDC
    black: 630VDC
    orange: 1000VDC

    Don't know about other countries.

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