Re: DC power supplies etc.

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

How much ripple can you tolerate?  10 uF is a lot of capacitance, at, say 10
kV and 100 mA...
Ripple = deltaT * I / C (roughly)...

100 mA, 8.6 mSec period, 1 uF = ca 900 V ripple... 10 uF = 90 V ripple...
(<1 % out of 10 kV....)

I might also add that the hazard of 500 Joules stored in a low impedance
source (that 10 uF cap) is signficant.  A short circuit or inadvertent
flashover will probably "break parts".

Inductive filters might be a better way to go

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Sunday, December 23, 2001 1:44 PM
Subject: Re: DC power supplies etc.


> Original poster: "Mike Nolley by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<nolleym-at-willamette.edu>
>
> > USA Manufacturing Surplus (http://www.usamfg-dot-net/) has microwave oven
caps
> > (2100 VAC or about 3 KV DC at 1 uF) for 50 cents each which is a good
deal.
> > Look in their on line catalog under capacitors.  They also have some
1500
> > volt 3 uF caps for 50 cents.  At these prices, you can gang a bunch of
them
> > in series/parallel for DC power supply use.
> > --Steve
>
>     That's a pretty good price, I might look into buying some of those.
Do
> you know of a manufacturer
> that sells good quality diodes at those prices?
>     There is also an issue with the oven caps as filter devices.  They are
> great for doubling
> purposes, but the filter capacitors need to handle the full voltage of the
> power supply--12kv or so.
> To get a capacitor of the required voltage and with sufficient ripple
> reduction (say 10uf) you would
> need... 216 capacitors.  Thats $108.
>     --Mike
>
>
>