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Re: [Amps] CD Cap

To: amps@contesting.com
Subject: Re: [Amps] CD Cap
From: "Will Matney" <craxd1@verizon.net>
Reply-to: craxd1@verizon.net
Date: Fri, 24 Mar 2006 01:09:55 -0500
List-post: <mailto:amps@contesting.com>
Ian,

With the med that my doc has me on, I'll be working the midnight shift for some 
time it looks like, hi hi!

Best,

Will

*********** REPLY SEPARATOR  ***********

On 3/24/06 at 12:33 AM Ian White GM3SEK wrote:

>Rich wrote:
>>Thank you Ian for your reply, please note that some of us are not real 
>>sharp on all of this so I must ask how do I find the "ripple current 
>>rating"? I bought the caps on ebay and did not find the info on CD's 
>>web site.
>
>Ripple current rating is the amount of alternating current that the 
>capacitors can pass without too much internal heating. In a capacitor 
>input supply, the caps are only charged in the parts of the cycle when 
>the transformer voltage is higher than the DC voltage stored on the cap 
>- and then a lot of current flows in a relatively short pulse. This 
>results in a strongly "peaky" waveform of ripple current passing through 
>the capacitor. (Can anyone point Rich to a graphic of the waveform on 
>the web?)
>
>In the kinds of power supplies we build for amps, the typical values of 
>RMS ripple current run at 1.5-2x the DC current.
>
>The effects of ripple current on capacitor operating temperature and 
>lifetime are often underestimated, which is why I suggested you try to 
>find out the ripple current rating.
>
>Can you find these capacitors on the CD website at all? If the data is 
>there, I would be surprised in the ripple current rating was not 
>included.
>
>Have you told us everything that is printed on the capacitors 
>themselves?
>
>>This also brings up another question, I am going to use an old 
>>transformer. It has 230 input , three input terminals , out put is 
>>terminals 1-2 , 3000vac , terminals 1-3 ,2090vac. Resistance is .45ohms 
>>in(1-2) or 1.02ohmsin, output R is 41.4. In another thread it was 
>>brought up about transformers for a choke input?? How do I tell and why 
>>do I care. This is an old surplus transformer even to the point of 
>>having spark gap balls in parallel with the output terminals.
>>
>This looks like one for the PSU Designer software.
>
>(Sorry, it's well past midnight here, and there's a long day's driving 
>to come tomorrow. Handing you over to the night shift, Rich... )
>
>
>-- 
>73 from Ian GM3SEK         'In Practice' columnist for RadCom (RSGB)
>http://www.ifwtech.co.uk/g3sek
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