capacitors

[marodu]

I've found some old capacitors and i want to put them in some of my audio projects.
Can you says some words about them.

[indianajo]

Electrolytic caps over 20 years old are experimental use only because of the rubber seals deteriorating from oxygen exposure. If they warm up the water will evaporate. These are the aluminum cans with a minus sign on one end, typcally >10 microfarad (mf before 1980, uf now). Huge ones like the 47000 mf one if connected to a powerful rectifier & transformer, can cause quite an explosion, so if experimenting, put these in a steel box and don't peer in to save your eyes.
The plastic film caps, the little squares, should be fine except if any are SCR brand. Sprague & mallory film caps made in 1965 are doing quite well. I don't know what brand these are, but I have some squared off film caps in my R***** S***** grab bags of the seventies, and they are still fine. Although RS stuff tended to be mismarked & rejects as much as surplus. These may not necessarily be the highest grade polyprophylene film, but when I replaced some paper caps with low cost polyester last year, I noticed some distortion improvement on the high frequencies of my PAS2 preamp.

[DF96]

Some of the small tubular ones look like polystyrene. Useful for tuned circuits or RC networks.

[AndrewT]

taking ages to download.
Why do we have to put up with this monstrosity of 1.8MB for the first pic which is 2700 pixels wide and coming from a remote server?

When are "WE" going to persuade the Forum to prevent this being allowed?

[jlsem]

Geez, how old is your computer?

John

[Salas]

Jason knows the issue, I don't know how complex it is to automatically resize externally hosted pictures, meantime I edited them smaller. And I repeat to members, please use attachments of logical sizes, not links. They are usually too big and expire, threads look orphaned and become incomprehensible after a while, attachments stay forever.

[wintermute]

Originally Posted by jlsem

Geez, how old is your computer?

John

Hi John, it isn't so much the age of the computer but the speed of the internet connection that is the issue. Not all parts of the world have the excellent infrastructure that the US have I have relatively fast Internet at home (around 3.5Mbps) and even on that the images took tens of seconds to download (yeah some of us are impatient )

I also use wireless (3G) internet on my laptop, and for that I pay by the megabyte (it's not hideously expensive but at 5c a megabyte it does add up). I choose that because in Australia for say a 5GB data plan you need to pay about $90 per month, I choose to pay by the megabyte and my monthly bill ends up around $7.00 per month, as my usage is generally low.

BTW the computer that I'm running on that took 10's of seconds to download the large images is a quad core 3.4Ghz Athlon 64 bit running windows 7.

Tony.

[Conrad Hoffman]

Then there are those of us with dial-up because we're too cheap/broke to have anything else. There's nothing there that should be more than a 50k file, properly sized and compressed.

The #3 Sprague I've seen more than a few failures over the years, but odds are it's still good. The #4 is a polystyrene and it and anything that looks similar will be excellent. They may not all be styrene, but probably are. The #12 is a stacked film cap, probably polystyrene and the ones I've got are excellent. They seem to come in higher values than the tubular ones. The rest of the flat film caps aren't exciting as they're just common cheap film caps. Any of the "plastic box" caps will be good films, though you'll have to track down the part numbers to tell exactly what kind of film they are.

[tomchr]

Originally Posted by Conrad Hoffman

Then there are those of us with dial-up because we're too cheap/broke to have anything else.

Dial-up... There's a word I never thought I'd hear again...

Actually, I think it's something like 40 % of the US population that's still using dial-up. Broadband or fiber has only covered the major metropolitan areas. Much like cell phone coverage.

I converted to a 6 Mbps cable connection in 2002 and haven't looked back.

But still... Big images are highly unnecessary.

Oh... Back on topic: Those film caps are quite good. All plastic caps are fine to use. It's only the wet electrolytic types that you have to worry about. Watch out if you're using the polystyrene caps. Don't use flux cleaner with PS caps as the acetone in the flux cleaner eats the polystyrene...

~Tom

[mjf]

hello.
probably:
4 polystyrene (polystyrol).for filtering,input caps in audio amps,rf-circuits......
7 ero mkt, old ,standard.......
12 siemens - epcos,mkh (= kind of mkt),uncoated (without case).......