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Re: Marx Question



Original poster: "Mike Harrison by way of Terry Fritz <teslalist-at-qwest-dot-net>" <mike-at-whitewing.co.uk>

On Mon, 18 Aug 2003 12:25:16 -0600, you wrote:

 >Original poster: "Jim Lux by way of Terry Fritz <teslalist-at-qwest-dot-net>" 
<jimlux-at-earthlink-dot-net>
 >
 >You bet there will be a difference.  For a Marx, it's all about energy...
 >----- Original Message -----
 >From: "Tesla list" <tesla-at-pupman-dot-com>
 >To: <tesla-at-pupman-dot-com>
 >Sent: Monday, August 18, 2003 6:56 AM
 >Subject: Marx Question
 >
 >
 > > Original poster: "John by way of Terry Fritz <teslalist-at-qwest-dot-net>"
 ><fireba8104-at-yahoo-dot-com>
 > >
 > > To anyone that has built a Marx before;
 > > Does the value of the cap affect performance?
 > > Will there be a noticeable difference if I use a 1.2 nF or a 150nf cap?

You certainly want to be above 1nf as below this losses really cut into the 
energy left for the
spark.

If the caps are really large then charge current gets quite high. If using 
resistive charging, this
means a lot of power dissipation and expensive resistors.
Inductive charging may be less useful with bigger caps, as the inductance 
will start draining away
some of the spark energy.

Assuming around 25KV input (monitor flyback), you really want to have at 
least 2nf per stage for
nice bright sparks. I'd think anything above about 10nf would require ear 
defenders...!

My last marx used 20 stages of 2.2nf at 25KV and works very well - 25" sparks.
www.electricstuff.co.uk/marxthree.html