Re: [CAD_CAM_EDM_DRO] Re: Re: Re: Power supply question.....

scott wilson wrote:

> Jon Elson wrote:
>
> >
> > I have built gear with over 10,000 22 uF 16 V Panasonic mocrominiature caps,
> > running on either 5 or 12 V, and had no trouble with them whatsoever.
> >
> > Jon
> >
>
> sounds like good conservative design.......
>
> Please remember that we are looking at the AC Component of the voltage being applied to the cap.
>
> for instance with a 24v xformer and full wave bridge you are putting either about 34v ac or more on that cap

No, completely wrong. There is a couple of volts of ripple on the capacitor,
depending on how much droop occurs due to the load draining the
capacitor between charging pulses from the transformer. If you put 34 V
peak on a sizable capacitor, it will explode within seconds. At no load,
there will be almost no AC on the capacitor. At full load, you would not
want to see much more than 1 V droop (at 120 Hz) under normal conditions.
If you use too small a capacitor, the droop will be larger, and the AC ripple
current may cause the capacitor to run hot and fail early. Another reason
to use a large capacitor is to ride through short power dips.

Jon