Re: power supply questions

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

Original poster: "Peter Terren" <pterren-at-iinet-dot-net.au> 


----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Saturday, September 06, 2003 9:22 AM
Subject: power supply questions


 > Original poster: "Christoph Bohr" <cb-at-luebke-lands.de>
 >
 > 2nd: I thought about using DC to feed my coil by rectifying the
 > xformer output with a series setup of 1N4007 diodes under oil and
 > charge a 30nF cap for cmoothing purposes. The main C1 would be
 > 60nF. Can this be done or has the smoothing cap to be bigger than
 > tha primary cap?
 > Christoph Bohr
 >
Hi Christoph
Just a note about using diodes. They need to be able to withstand the
voltage between the peak capacitance voltage and the peak reverse voltage of
the transformer output ie 2 * (15 sqrt 2 )  Kv = 42 Kv.  If you then allow
10% for the potential variac voltage rise and allow 50% margin for error (as
the diodes may not divide voltage equally when changing state) = 69 KV.  ie
you need at least 70 x 1N4007's. This is a lot more than the 15 you might
expect and is probably why people regard DC as unreliable because they blow
the diode strings.

I am rectifying 40 Kv + with 290 x 1N4007's which is borderline.

Cheers
Peter (Tesla Downunder)
http://members.iinet-dot-net.au/~pterren
Geek Group ID#1601