Re: DC power supplies etc.

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

Original poster: "S & J Young by way of Terry Fritz <twftesla-at-qwest-dot-net>" <youngs-at-konnections-dot-net>

Mike & all,

Remember, the MO caps are rated for AC volts.  Thus a typical 2100 volt cap
is rated for 1.414 times that or about 3 KV DC.  4 in series is 0.25 mF at
12 KV, or 16 of them is a microfarad at 12 KV DC.  Several knowledgable
coilers on this list have stated the DC filter cap doesn't need to be any
more than about 10-20 times bigger than the tank cap.  So 1 mF should be
plenty good for up to 50 nF tank capacitance.  Even if you went to 4 mF,
that is only 64 caps costing $32 which isn't bad.  10 mF would take 116 caps
for $80.  A little ripple doesn't hurt anything.  My current power supply
uses 8 MO caps which is only 0.5 mF at 12 KV and it works fine with power up
to 1.4 KW with a 26 nF tank cap.

Once in a while USA manufacturing has beefier caps at terrific prices.  I
got some 23 mF 4 KV caps from them for about $2 each - the shipping was more
than their cost!

Diodes such as the 1 amp 1000 volt 1N4007 are available from many sources at
just a few cents each in lots of 100.  Pick your voltage and put enough
diodes in series to withstand x2 to x3 PIV and you are in business.  Just
takes a bunch of soldering.  You can buy half amp MOT diodes for a few
dollars each as well.  Rick Williams has a good source.
--Steve


----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Sunday, December 23, 2001 2:44 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
>
>
>