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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