Non polarised capacitors.

[Nanozeugma]

Hi.
I was curious regarding peoples experiences in choosing modern replacements for venerable (guaranteed leaky) paper capacitors of the various types found in old electronics.

The most common type used appears to be the yellow bodied axial polypropylene film type; these are not (in the main) ferociously expensive if you choose your source with care. These are primarily sourced from U.K. sellers, though may be made elsewhere.

Significantly cheaper are the brown radial metal film capacitors primarily (but not exclusively) offered by sellers in mainland China and Hong Kong.
These normally have quite long lead out wires which may be bent parallel with the body and are perhaps less obtrusive in old equipment than the yellow.

Normally cost is an excellent barometer of quality but is not necessarily a guarantee of it.
I have used both types without issue but wondered whether others had issue or thoughts regarding the brown ones.
(Excluding from the argument that most, if not all of the Chinese caps have ferrous metal leadouts (are some yellow ones are not immune either.))

[evingar]

I've used the yellow polypropylene types almost exclusively for replacing "waxies". Given the effort required to change some caps in vintage equipment I wouldn't, personally, risk buying from non accredited suppliers

[paulsherwin]

The only real reasons to choose one type of modern plastic film capacitor over another are cosmetic appearance and ease of installation. Coupling and decoupling in domestic valve radios aren't demanding applications.

[dazzlevision]

Hello,

I use the yellow bodied Polyester film capacitors made by Vishay Roederstein: http://www.farnell.com/datasheets/20...SAAEgL41fD_BwE

The "RS Components" supplied Polypropylene one in your photo is a high voltage type that is not often used in valve radios - more suitable for pulse and HV applications in old valved TVs.

However, Panasonic (was Matsushita) Components do supply the Polyester film brown cased radial lead type: https://cpc.farnell.com/panasonic/ec...1uf/dp/CA07027 I also use these.

[Nanozeugma]

dazzlevision:
Thank you for your input.
Just to clarify, the yellow polypropylene capacitor image I chose was merely to illustrate the general appearance of the type. I normally use 630 vdc types unless the circuit calls for a higher voltage (isolation or secondary of OPTX as examples.)

[snowman_al]

As Paul says one is not better or worse than the other for these applications
My choice is to use like for like for the sake of appearance. Axial for axial etc.
If the yellow bothers you paint the body a better colour match to the originals. I use matt black or light grey normally.
I think the cost difference is that the radials are made in much greater quantities (for PCB mounting rather than point to point) than axials?
Alan

[AC/HL]

I wonder who decided on yellow?

[Refugee]

A brown magic marker tames the yellow if you are worried about it.

[Maarten]

I'm not sure about the modern bright yellow, but I think the first yellow capacitors would be the Philips dipped metalised polyester foil capacitors a.k.a. Mustard Capacitors. For the first few years of production, they were actually green but the yellowish epoxy must have been better and/or cheaper. Philips later experimented with a colour coded outer layer but that flaked off easily so they went back to mustard coloured dip (even on radial types) and later settled for orange. The orange may have been chosen for availability reasons since other manufacturers used it already.

The modern yellow foil capacitors however, seem to use transparent expoxy but a yellow outer foil, possibly chosen for a good contrast of the print (even for the colour blind, that could have also played a role).

[joebog1]

The brown polyester film caps are "probably" best for reasons of cost and size. They are also available in many voltage ratings, 50V, 100V, 250V, 630V and 2000V. They are very good quality, even those from China. ( I would think they are ALL made in China now).
As dazzle already mentioned the specific RS components polypropylene are usable but I have found them " not the nicest sounding" to be an audiophool. Mustard caps from Philips are REAL metal foil, not spray painted metal film as are the brown cap you show. These brown caps were first released as greencaps BTW, and if you are searching the web for them, you will get many hits.

There are a few "oddball" domestic radios that used somewhat higher voltages then what is "normal, which for most mantle sets or kitchen radios is around 200 - 300 volts.
So there isnt much point in going higher than 630 volt greencaps, as that should cover 99% of rebuilds or repairs. The problem with them is the shape, which doesnt make for easy insertion into the body of a waxie to keep the innards as authentic as possible. That said, after using "greencap" style capacitors for around 40 years, I have not had a failure in any repairs or rebuilds.

Joe

[G8UWM-MildMartin]

I have found Rapid's axial and radial capacitors to be entirely satisfactory and cheap when bought by the hundred:
https://www.rapidonline.com/jb-capac...ter-10--563131
https://www.rapidonline.com/suntan-m...apacitor-71096
For higher voltage, the LCR PC/HV/S range from CPC are excellent; not so cheap, but still worth the money:
https://cpc.farnell.com/search?st=PC%2FHV

[Maarten]

@joebog1: Are you sure Mustard C's are solid foil instead of metallised polyester? I don't have my databook handy right now, but I think it mentions they're metallised (sputtered on).

Also, forgot to mention: the construction of the brown radial dipped capacitors is probably very similar to that of the radial Mustard C's.

[joebog1]

In the interest of science, I have sent a new .01uF 160 volt mustard cap to the cap graveyard and crushed a cap to show its construction. I have taken about 10 pics, but only one ended up good enough to show the construction.
With the aid of an loupe I can see the foil which of course is incredibly thin.

For the life of me I cannot take a pic that shows it clearly

Joe

[Tim]

Used both of above (including the "brown ones" from Rapid) for last 7-10 years and have had no complaints or returns yet.

[G6Tanuki]

I've seen some of the brown-type capacitors fail when used as droppers in Chinese LED "GU10" bulbs - this makes me suspicious of them.

If replacing cylindrical waxies I instinctively reach for yellow Vishay MKT-types from a reliable source [RS/Farnell/CPC]. They're not the cheapest, but they do have some source-traceability and - unlike some of the untraceable-source stuff from Ebay/Alibaba I don't feel the visceral need to test every one before fitting it.

[Maarten]

They probably failed because they use a 250V polyester film where a 400V or 630V polypropylene would have been appropriate. That said, it could have had a manufacturing defect, there are likely to be differences in quality between manufacturers.

[MurphyNut]

Originally Posted by AC/HL

I wonder who decided on yellow?

I've often thought that, a shame they aren't a more toned down colour and less plastic looking.
Shouldn't grumble I've installed hundreds of them and never had any problems.

[Refugee]

Does anyone know how many yellow caps can be toned down with a brown magic marker?

[Studio263]

RS sell the brown radial ones made by Nichicon; made in Japan. Still not expensive and excellent quality.

https://uk.rs-online.com/web/p/polye...itors/7554450/