Re: LTR vs. more primary turns

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

Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>

Hi All,
         I should have added a further note to this reply:

 > Hi Chris,
 >
 > On 3 Dec 2002, at 22:36, Tesla list wrote:
 >
 > > Original poster: "Chris Roberts by way of Terry Fritz 
<twftesla-at-qwest-dot-net>" <quezacotl_14000000000000-at-yahoo-dot-com>
 > >
 > >
 > > Hello, it's me, the guy who can't build a tesla coil right. =P
 > >
 > > Since my big coil is out of order for a while, I'm going to take some of
 > > the caps off of it and use them to build a 4kv, 38ma mini coil. 
However, I
 > > ran into a problem. We all know how a LTR cap increases the coil output,
 > > but as I was running calculations, I found that the higher the tank
 > > capacitance the fewer the number of primary turns it required to reach
 > > resonance. But I read on John Freau's website
 > > 
<http://hometown.aol-dot-com/futuret/page5.html>http://hometown.aol-dot-com/futuret/page5.html 

 > > that using a higher number of turns on the primary will increase primary
 > > surge impedance, and will reduce spark gap losses. Is this true? If it 
is,
 > > then I pose the following question: Using a given secondary frequency, is
 > > it better to have an LTR cap with relatively few primary turns, or to 
have
 > > a smaller tank cap and more primary turns? Thanks for your infinite
 > > knowlege and wisdom.
 >
 > What John said is true. Starting from a given secondary is not the
 > best way to design a good coil. You should be starting from the
 > capabilities of your chosen supply. That is exactly how I design
 > coils. Once you've wound the secondary, you're stuck with it for
 > better or worse.

The other valid approach is to start off with an output specification
and build and choose components to do the job. This approach assumes
no restrictions on component availability, money or skill needed to
buy or build them.

       In my case, a 230V 10A wall socket is the starting point for an
"open-ended" "domestic" system. Transformers on hand (if I'm happy to
live with their restrictions) dictates the first course of action.

Regards,
Malcolm