Model T First Light - Take Two

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

Original poster: "David Kyle by way of Terry Fritz <twftesla-at-qwest-dot-net>" <dave-at-kyleusa-dot-com>

I completed the redesign of the Model T Spark Coil powered Mini-coil and
achieved first light. I measured a 1.25 inch spark which admittedly is
pretty puny but when you take into account that it is powered from a
battery powered Model T spark coil this really is not too bad. No
breakout but placing a sharp point on the toroid will yield a 1/4 inch
discharge. No doubt far greater output would result with more input
current.

Specs are as follows:

- 12 volt sealed gel cell battery power source
- Pep Boys reproduction spark coil from 1968 (my mother bought it for
me)
- Thoriated Tungsten spark gap set to slightly over a 1/16 of an inch
- 12 inch helical primary wound with 1/8 copper tubing, tapped at turn
20
- 2 x 2000pf doorknob caps at 40KVDC in series for a total of 1000pf at
80KVDC
- 18 inch secondary wound with 1000 turns of 26 gauge wire on 3.25 inch
thin wall PVC tubing
- 6 inch spun aluminum toroid
- Current draw is slightly less than 2A at 12VDC
- Calculated resonant frequency is 421KHz

Tuning was a breeze as it came up exactly as predicted by JavaTC. Being
very low power permits some interesting investigations since it is
possible to map out the field of the coil with a small neon tube with
out fear of electrocution. Fluorescent tubes easily light up about 18
inches from the coil. The coil operates fine without a ground reference
and the discharge slightly decreased when a ground reference was
connected.

I am very grateful to the assistance that this list provided. This coil
is your success as well. 

It is worth noting that I learned far more from the failure of my first
attempt with the mini-coil than in my previous successes with my big
coil. Failure is a great teacher if you are willing to listen.

Pictures can be found at the bottom of the following page:
http://home.austin.rr-dot-com/dkyle/tesla_gallery.htm


=========================================
Dave Kyle
Austin, TX USA
Email: dave-at-kyleusa-dot-com