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Triophile 6th April 2005 10:09 AM

Seeking ultra, ultra mini 1uF elec cap
 
Morning, all.

I'm thinking about modifying a Sony WM-DC2 Pro walkman. There are eight 1uF tantalum coupling caps in each channel, which I would like to replace with something that causes less distortion (going by what Cyril Bateman wrote in his series of articles on cap distortion in Electronics World a while back). Trouble is, I'm very, very limited in terms of space inside the walkman, and 5mm dia x 5mm high electrolytics are just a bit too big. Does anyone know of any alternatives which are smaller? The voltage rating on the cap doesn't need to be more than about 6V-9V (if that, actually. I might be able to get away with 4V).

I had a look at Panasonic's specialty polymer SMD caps, but I couldn't find any in a 1uF capacity. Any suggestions greatly appreciated.

Cheers, Jon.

peranders 6th April 2005 10:35 AM

Re: Seeking ultra, ultra mini 1uF elec cap
 
Quote:

Originally posted by Triophile
[B....There are eight 1uF tantalum coupling caps in each channel, which I would like to replace with something that causes less distortion....[/B]
How much is it now and how high is acceptable?

Bricolo 6th April 2005 11:09 AM

Wima MKS2 are one of the smallest "good" film caps I know

peranders 6th April 2005 11:35 AM

I think the 1 uF he wants or needs must be _really_ small, like a head of a match.

Bricolo 6th April 2005 01:01 PM

afaik, there's no ceramic cap up to 1uf
tantalum is what he wants to get rid of
if electrolytics are too big, film caps are the only choice left
and metalized polyester (MKS) has the higher capacity/space ratio

so if there's no 1uF MKS cap that fits...
use a smaller value (1uF seems high for a line level AC coupling, and low for a 32R headphone coupling)
keep your tantalums
direct couple if you can (or change the topology to be able to direct couple)

tiroth 6th April 2005 01:44 PM

There ARE ceramic caps that big, but if anything they will have much worse shock noise figures and would be a poor choice for a walkman.

You might consider aluminum/organic polymer caps; they might not be as good as film but they are probably superior to tantalum, and are easily available in large sizes.

robbie b 6th April 2005 02:04 PM

Look at the Blackgate PK and N or NX HiQ types. The smallest are 4 by 7 mm.
A bit pricy but perhaps they fit.

:)

Rob
http://www.partsconnexion.com/catalo...ctrolytic.html

jcx 6th April 2005 03:07 PM

digikey carries panasonic smt film caps

they have a "submicron" ECP-U series with 1 uF 10,16V in 1206,1210 smt packages

http://industrial.panasonic.com/ww/i.../ecpupoint.pdf

I think this is PEN (mylar?), not the best film but miles ahead of any electro or hi K ceramic - these are probably a little worse than typical 50/100 V polyester caps

I would use the higher V 1210 part

they're small enough the truly obsessive could parallel/series them for lower V stress (and presumably, lower distortion) - for coupling just paralleling a few would drop the corner freq and might be worthwhile

Triophile 6th April 2005 10:39 PM

Many thanks for all the informative replies. I'll check out the link to the Panasonic caps.

I don't know what the distortion is with the tantalum caps - I was just thinking of trying to use cap types which, according to Cyril Bateman's articles, would produce less distortion. Maybe I've got too much time on my hands... OTOH, I do like my DC2.

I'd probably struggle to direct couple the existing circuitry, because of lack of sufficient electronics knowledge, lack of space, and only a single supply rail. I had thought about pulling out all the existing circuitry bar the motor controller and starting from scratch with someone else's tape head and headphone amp, but life's (probably) too short.

Cheers, Jon.

Triophile 6th April 2005 10:42 PM

Sorry, I should have added that any caps would have to be no more than about 4mm or 5mm long and 3mm or 4mm high, which rules out any of the 5mm x 5mm ultra-mini electrolytics I've seen thus far.

Cheers, Jon.


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