Former thoughts (was Re: 20 gauge wire)
Several thoughts and comments down below.
Original Poster: Adam <adamsmith-at-mediaone-dot-net>
on 2/9/2000 9:14 AM, Tesla List at tesla-at-pupman-dot-com wrote:
>> Original Poster: "Reinhard Walter Buchner" <rw.buchner-at-verbund-dot-net>
>> Bottom line: Donīt expect a great performance increase with your
>> new coil former being wound with AWG 22 instead of AWG 20. If
>> you see more than a 10% increase in output, it would *really*
>> surprise me.
>Well, I would be quite happy if I got 10% more spark from
>this secondary alone, but my real reason for my building a
>larger secondary is to allow me to use a larger primary cap
>and more input power. I'm going from 0.01uF to 0.03uF, and
>I need both a larger secondary and a larger toroid to be able
>to tune this system without having to build a larger primary
>coil (not an option for me right now).
>I had an 8" x 25" x #20 secondary, and I'm replacing it with a
>9.625" x 29" x #22 coil. My old power supply was 9kV -at- 120mA
>NST, my new supply is 12kV-at- 180mA from NSTs.
- Using your 9kV setup, your 8" coil was only being fed with 0.81
Joules. This is way too little power for an 8" coil. What kind of
arc lengths were you achieving?
- Your new setup will supply around 4.32 Joules, which can still
(quite easily in fact) be managed by your 8" coil.
- Both your old coil and your new coil are on the *fat* side. I mean
the h/d ratio is too low (~~3). A better ratio for higher powered
coils is 4.5 - 5.0. Your *squat* coil is too short for high power
discharges. I know there are exceptions (R. Hullīs cool magnifier),
but I would strongly suggest you lengthen the former quite a bit. This
will then also allow you to use thicker wire (for the same L).
- I am presently running my 7.82" x 32.93" (screwy size due to metric
conversion) coil with 3.8 Joules and plan on feeding it with up to
11.25 Joules in itīs final config. The planned topload for this setup
will be 10" minor diameter and 65" in major diameter plus an
additional smaller anti corona (E-field shaping) toroid below this. I
think I should be able to squeeze some 10-12 ft arcs from it. I did
do quite a bit of preparation work on the secondary, tho, as I
personally think that secondary former preparation is the A & O of
high power coiling work.
- As your new coil is larger in diameter and you wonīt be changing
your primary, you will have less distance between the primary and
your new secondary, which could lead to flash over problems, esp.
since you will be feeding it more than 5x the power of the old setup.
- Just out of pure curiosity, why canīt you change your primary
configuration? Even if you need to redesign your coiling table, etc,
this would still be the better and probably cheaper, too option (I
- To tune your new PSU to your old former and topload, you could
always use an off-axis inductor. This will lower your coupling,
but you can always raise the primary in relation to the secondary.
That way, you can inexpensively experiment with your new setup
and once you have the bugs ironed out, you can go to building that
killer secondary ( & former) and a new primary to *really* match it
Just some fuel for thought.
Coiler greets from Germany,