Cap voltage rating (was Re: Power supply question.....

Hi Scott and all,

I've been reading the threads about power supplies and caps and
transformers and all with great interest.

Seems to me that the preference is Torridoidal transformers and huge
capacity cap's, but the cap's voltage is not suposed to be lots more
than the expected voltage of the system. is: if you plan on a 35 volt
power supply, 24 VAC trans + cap, a 50Volt cap would be good, but a
100 Volt cap would actually not be a good choice.

On my 12 supply from my computer, it has 500 volt cap's. it is a
dual power, 220/110.

Then there is the voltage increase from the steppers when not being
driven, but still spinning.

Is there a good rule of thumb (or actual engineering principals ?)
to size a capacitor ?


Dave

--- In CAD_CAM_EDM_DRO@y..., scott wilson <swilson@d...> wrote:
> have seen several pwr supply questions about caps....and it seems
to me that if they are being used as brute filter caps people are
using way to low a working voltage....in this case i would feel much
better with a 80-100v rating....and yes you can put them in parallel
>
> RC wrote:
>
> > Building my first power supply, needs to be approx. 42 volts @ 10
amps.... I will need a cap with a 19,000 mf value with at least 50
v. rating, the question I have is, can one "add" the mf values,
instead of using one large cap? And if so, how would they be
connected, series or parallel?
> >
> > Thanks,
> > RC
> >
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