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Vintage threads from the first ten years

Cap Voltage Ratings

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5/4/1999 6:21 AM
wink	Cap Voltage Ratings I have some electrolytics on which the voltage ratings are printed 'WV' and some are 'VDC'. Is there a difference in these ratings? i.e Is a 50WV the same as a 50VDC? wink

5/4/1999 6:40 AM
jason	they are the same. jason

5/4/1999 9:39 AM
Bruce	I think WV means working voltage, Wink. Bruce

5/4/1999 1:18 PM

Hi Wink,

"WV" does mean "working voltage" as Bruce has stated and reflects the voltage at which the caps will operate safely. So, "50WV" and "50VDC" are the same.

Certain circuits, like VT rectifiers, will initially produce large voltages. After the tube warms and current begins to flow, the voltage drops. This is the "surge" voltage that filter caps must endure. Without looking at a paticular cap's data sheet, it's hard to guess what the rated surge voltage may be. One thing to be sure of: the voltage rating listed on the cap body is definitely NOT the surge voltage.

Later,

Dave James
James Music Products

5/4/1999 2:20 PM
wink	Thanks Y'all. Now let me explain why I asked the question. I just got some Sprague Atoms that I ordered from Mouser. They are 50uF at 50VDC. The caps that I am replacing are ELNAs. They are 50uF at 50WV. The ELNA's are about 4 times the physical size of the Spragues. The ELNAs are about 40 years old. This size difference had me concerned. comments? wink

5/4/1999 2:59 PM

By today's standards, Sprague Atoms are large!! For example, a Sprague Atom 20uF/500v cap has about 2-3 times more volume than the equivalent import IC brand 22uF/500v cap. The atoms are excellent caps -- I wouldn't worry about size as long as the ratings are sufficient. It couldn't hurt to measure the voltage across the new cap (not the old one - might be too leaky) to make sure it is actually less than 50 volts. If it is, then you can sleep at night. By the way, what type of circuit was the ELNA being use in?

5/4/1999 4:42 PM
wink	These caps are cathodes to ground (bypass?) in the output section of a stereo integrated amp. This thing is a Trio Radio Corp. Model W-45. The best I can tell, it was made in Japan in the late 50s. It is a restoration project. Basic circuit design, 12au7s feed 12ax7s to 6bq5s in a push-pull configuration. wink Why this forum you say? I am also building an AX84 guitar amp.

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