Re: DC TC

To: tesla-at-pupman-dot-com
Subject: Re: DC TC
From: "S.Gaeta" <SGTPORKY-at-prodigy-dot-net> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
Date: Sat, 18 Mar 2000 07:12:44 -0700
Approved: twftesla-at-uswest-dot-net
Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

----- Original Message -----
From: Tesla List <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Thursday, March 16, 2000 6:30 PM
Subject: Re: DC TC


> Original Poster: "Ruud de Graaf" <rdegraaf-at-daxis.nl>
>
> Comments are 'interspaced':

Ditto

>
> >Original Poster: "S.Gaeta" <SGTPORKY-at-prodigy-dot-net>
> >
> >That's an excellent question! I tried it once myself. I used a rectifier
on
> >each leg to do the full wave thing. I did not use a filter cap. I simply
> >threw the diodes in and didn't change anything else. This did not work as
> >well as well as using one leg of the NST in the AC mode. I really
expected
> >an improvement with DC but got the reverse.Can someone please tell me
why?
>
> Hmmmm...a rectifier on each leg,  that would be two diodes, right? That's
> not the Graetz configuration i know of (4 diodes). I think you eliminated
> half of the wave.

No, actually I cut the voltage in half, but it's still a full wave
rectification scheme. I put the anode of one rectifier to one side of the
NST, and the other rectifier anode to the other side of the NST and tied the
two cathodes together. This is the positive terminal. The negative terminal
is the center tap of the transformer which is grounded. I should have
reversed the rectifiers to see if it made any difference. It would have been
an interesting experiment. You are thinking of a full wave bridge, which
would have doubled the DC output voltage. I didn't do this for two reasons.
One is that I had only three of these rectifiers and the other reason is
that at that time, the only cap I had was only rated for 30KVDC, and the
only NST I had was a 15/30. I didn't want to blow the cap so I cut the
voltage in half. So naturally for the DC run I was using both halves of the
NST and for the AC run I only used one side and case(ground).
>
> >The rectifiers were rated for that voltage and current and were still
good
> >after the run (my cap told me so when I discharged it-with a high voltage
> >cable in case anyone was wondering :-))
> >
> >The added inconvenience is that now you MUST discharge your cap. Your
> >transformer will not do it for you with the diodes in place. Of course
it's
> >a good idea not to depend on the transformer winding to discharge the cap
> >anyhow even when running AC because something could go wrong.
"Transformer
> >discharge" also will not work for multiple caps in series.
> >
> >S.G.
>
>
> I'am afraid I disagree: you MUST use an always connected resistor too
> discharge the cap!!!

Okay, that works too, but I trust my stick more than a resistor that can
burn out. My stick, by the way actually consists of two 3 foot long lexan
sticks that are tied to each of a HV cable. Some of the left overs from when
I used to work as a tech. at a high voltage power supply company. Of course
the resistors can save your butt in the event that you forget to use your
stick. But I never foget to use my stick. Sometimes I forget to remove them,
and when I plug the coil in and turn up the variac I get nothing but a nice
soft hum from the transformer.

> And for safety you let the cap shake hands with your largest screwdriver!

BAP!!!!!!!!!

S.G.

<SNIP>

> AC: simple, fast problem-solving
> DC: independent of 50/60 Hz wave
>
> Take your pick!
>
> Ruud de Graaf
> Greetings from Holland
>
>