* Originally By: Froula-at-cig.mot-dot-com
 * Originally To: Richard Quick
 * Originally Re: RE: TESLA VIDEO
 * Original Area: UUCPE-Mail
 * Forwarded by : Blue Wave v2.12

Date: Thu, 19 Jan 1995 12:57:40 -0600
From: Don Froula <froula-at-cig.mot-dot-com>
To: richard.quick-at-slug.st-louis.mo.us

Richard, I've had a few days to review your tape.  Besides being blown away by
the sparks (!), I'm really impressed at how you've taken a very methodical
approach to increasing your coil performance.  It certainly has paid off in

Actually seeing the materials and construction methods involved is really a
great help to my own little project.  Also, the one small test coil you fired
using the shop vac blower-quenched static gaps give me a good idea of what to
shoot for in terms of performance from my coil.

I have a few specific questions.  I'm planning on building a 6" coil, 24"
winding length wound with 22 ga. enamelled magnet wire.  I was planning on
using 60' of 3/8" copper tubing for the primary.  I am tentatively planning
on a single 15,000 V, 60ma. neon transformer to power it, using a balanced
circuit like in your big coil.  Each leg of the circuit will use two
.012, 25,000 V. oil filled commercial capacitors in parallel.  This should
provide .012 mf of tank capacitance at a DC voltage rating of 50,000 volts.

        - Is the rating on the commercial caps conservative enough for the 15KV
                transformer?  I could step down to a 10 or 12 KV unit.

        - Is there any real performance advantage to winding the primary in
                a saucer rather than a pancake configuration?

        - I was planning on eliminating the bypass caps on the filter circuit,
                using only a protective gap and chokes for tank circuit
                isolation (along with a line filter on the neon primary).  Is
                this adequate protection for the transformer in a circuit
                like this?

        - You mentioned excessive kickback unless the capacitive values of the
                two tank legs were carefully balanced.  How important is this
                in a coil of this power level?

        - I was planning on using your "air blast" single quenched gap design
                from the GIF.  Will this supply reasonable performance for this
                coil?  How about using a high-power vacuum cleaner blower fo

        - Any suggestions on spacer construction for the primary?

        - How important is the variac for tuning a coil of this size?  I have
                a 7500 V, 30 ma unit I could use for lower power tuning.  Can
                I get by without?

        - I found some 18" outside diameter, 2" cross section styrofoam
                toroid forms in a local craft store.  I was planning on
                covering this with aluminum tape and adding an aluminized disk
                center support.  I calculate a surface area of just over 100
                square inches for this terminal.  Is it adequate, or would I
                do better with the 4" drain pipe version.

Many thanks for the phone call and the tape.  We had a showing here at Motorola
for a half-dozen or so engineers who are Tesla afficionados.  It was a real
thrill for them!  Here in the cellular radio division we're dealing with
high freq, low power.  It's nice to see what can be obtained with the opposite

Best Regards,


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