Re: matching secondary size to power supply

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

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <FutureT-at-aol-dot-com>

Justin,

The choice is not super-critical, but there are rules of thumb.

For example if you build an efficient coil which follows
spark length (inches) = 1.7*sqrt (input watts), then you'll
want the secondary to be at least 24" tall for a 60" spark
at 120 bps.  If the coil is shorter, it will most likely break
down voltage-wise.  This would limit the input power to about
1300 watts at 120 bps.  At a higher bps, the bang size will
be smaller, so the spark length can be longer and the input 
power can be higher, for the same input wattage.  If the
coil is not efficient however, then much more power can
be used, since the spark length is more of a limiting factor
for shortening the secondary coil, (but always taking BPS
into account).  

As further examples, I use a 19" tall secondary with 800 watts
input for a 42" spark length.  Richard Hull used a 48" (?) tall
secondary for his nemesis coil which gave 15 foot sparks
at 11kW, at a higher break rate.

If you're refering to secondary diameter, This can range
from a 1:3 ratio for diameter to height, to a 1:6 ratio or so.

Figure the wire size so you get 1000 to 1500 turns.

John


>
> Hi All,
>
> How do I choose the correct size of the secondary for each power supply?
> How critical is the choice?
>
> I have a number of power supplies to choose from and I recently asked
> someone this question and was told that 6, 8 or 10 would be suitable for
> that psu.  But which one would be best?
>
> There are two coils I want to build.  One is my big 5kW MOT coil (4 mots
> to begin with, possible 6 later) and the other is a small table top coil
> using a 10kv 30ma nst.  I have a few other NSTs to choose from as well.
>
> Is there a particular method to choosing the size for each psu?
>