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mashaffer 29th July 2008 11:54 PM

salvaged capacitors
 
I am looking for information on the safe use of salvaged capacitors. I know that electrolytics require extreme caution in reuse but what I am interested in is other types such as Polypropylene, ceramic etc. It seems like the ceramic disks and Polys should be fine if they test well but I have a lot of caps that I can not identify type nor determine whether there are issues in reusing them.

One type of specific interest looks like a small sausage of molded plastic with axial leads. They are rounded on the end and look like solid plastic. One is labled 0.1 and 600V.

Can someone suggest web resources.

mashaffer 30th July 2008 06:02 AM

2 Attachment(s)
Found this picture on Ebay. A lot of the caps are similar to these.

Elvee 30th July 2008 07:21 AM

Hi,

They could be paper or plastic foil caps. If they test OK, you can reuse them without problem. Be aware that they are general purpose, low grade types: you can use them for non-critical applications such as coupling or decoupling, but in filter applications, they would give poor performances.
LV

pilli 30th July 2008 11:03 AM

Also look at this:

http://www.diyaudio.com/forums/showt...951&highlight=

Where they suggest techniques for identifying plastic cap types, based on capacity change when heated (positive or negative drift) and on the smell when burnt (but this is a "nonreversible" test).




_

mashaffer 31st July 2008 01:55 AM

Thank you folks! Very helpful information. By poor performance in filter applications do we mean instability of the capacitance or other negative factors?

I have a lot of caps that look like orange drops that could be used in solid state filtering applications. Unfortunately (but not surprising given that the came from solid state organs) the "orange drops" and the "brown drops" (look like the common Chinese poly caps) all seem to be low voltage versions. I was really surpresed to find the 600V caps in there. Not always easy to figure out the voltage rating.

Just gotta find more vacuum tube stuff to salvage. :D

Elvee 31st July 2008 06:43 AM

Quote:

Originally posted by mashaffer
Thank you folks! Very helpful information. By poor performance in filter applications do we mean instability of the capacitance or other negative factors?


Temperature stability could be a problem in some cases, because, the tempco is rather large, positive and non-linear, but I was thinking more of the loss factor: dielectric absorption, etc.

Nordic 31st July 2008 07:04 AM

I think for the most part, you could improve on most of those parts with modern equivalents made from better materials for reasonably low cost.


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