Re: Advice for an Old Coiler

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

Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

Hi Dave,

At 12:08 AM 7/19/2001 -0500, you wrote:
>Hello,
>
>I built my first coil more than 30 years ago and still have the science fair
>award to prove it but I dropped out of high voltage after high school. Once
>again I feel the need create lightening and this group has been the answer
>to my prayers. The dedication to the science of Tesla's work is most
>impressive but I am absolutely stunned by the vast advances in coil
>construction techniques that this group has pioneered. The quality of ideas
>and the ingenuity in bringing them to fruition has spurred me to call back
>the lightening.

Cool!  We have tried a lot to modernize coils and the science behind them,
and we have been real successful :-))  Today's coils are a far cry from old
coils and new comers can build some really nice coils with great
performance.  Unlike my first days when I had zero idea what I was doing,
now you can get for more info than most people want to know on the
Internet...  The latest and greatest ideas and the experts on only a few
hours away now :-))

>
>I do have some questions whose answers I hope will make my project go
>smoother and I ask for your comments and suggestions. A brief description of
>my design follows:
>
>AC filter, 10 Amp Variac control panel

Perfect!

>
>Two 15KV -at- 30ma NSTs banked for 15KV -at- 60ma with power factor correction

Perfect!

>
>RC protection circuit

Great!  You may want to check out:

http://hot-streamer-dot-com/TeslaCoils/Misc/NSTFilt.jpg
http://hot-streamer-dot-com/TeslaCoils/MyPapers/MyPapers.htm
http://hot-streamer-dot-com/TeslaCoils/MyPapers/rcfilter/rcfilter.html

>
>Two .03uf 35KV Maxwell caps in series for .015 -at- 70KV

With a sync gap, you could go to about 27nF for about 70% more power or 30%
more spark length.  I would put the caps in parallel.

>
>1800 RPM SRSG 120 BPS with .1 inch thoriated tungsten points from a wielding
>shop

Perfect!

>
>14 turn .25 inch copper tubing secondary, adjustable tap, 15 degree saucer
>shaped with strike rail
>
>6 inch thin wall PVC primary with 1000 turns 24 gauge magnet wire
>
>6 inch toroid for spark suppression and a 6 inch copper sphere topload
>
>Tank circuit to be wired with 1/2 inch wide solid copper ribbon
>
>RF ground 1 inch copper ribbon going to an eight foot ground rod driven into
>damp earth
>

All perfect!

>
>Design goal: I should be very please to see three foot or greater sparks.

Should not be a problem.  You will get four feet if everything is just right.

>
>
>Questions:
>
>Do you think I would benefit from additional caps. If so how much? I was
>thinking of doubling to .03uf if needed.

Put the caps in parallel.

>
>What diameter disk is recommended for an 1800 RPM SRSG? I was thinking 6
>inches but others seem to prefer wider disks. Why is that?

The electrodes should not be allowed to arc to the center shaft.  As long
as that works, the diameter is not important.

>
>I was planning on four stationary gaps in series with four rotors. Is this
>the best arrangement?

I would use four rotating electrodes and two stationary:

http://hot-streamer-dot-com/TeslaCoils/MyCoils/BigCoil/Rgap.jpg
http://hot-streamer-dot-com/TeslaCoils/MyCoils/SmallCoil/small_gap1.jpg

>
>How wide to adjust the gaps in a SRSG?

As close as you can without the worry of them hitting.

>
>My synchronous motor may need to be replaced as I am unsure if it is of the
>type that syncs from the same position at startup. It is a brand new
>synchronous motor from Oriental Motor. Has anyone any experience with these?

If it is "non-salient", you have to adjust the dwell timing each time you
power it up.  I would get another motor if that is the case.  Adjusting the
motor gets real old...

>
>It also remains to be seen if a 1/30 HP motor is going to be adequate. My
>disk will be fairly light weight so I think it will be ok.

My non salient motors used to be 1/25th HP.  They would over heat after
about 10 minutes:

http://hot-streamer-dot-com/temp/OldGap.jpg

Convert a 1/4 HP standard AC motor:

http://hot-streamer-dot-com/TeslaCoils/Misc/syncmot.zip
http://hot-streamer-dot-com/TeslaCoils/Misc/sync_motor.txt

>
>What options for electrically varying the sync position of a motor exist?

See John's cool controller:

http://hometown.aol-dot-com/futuret/page3.html

>
>Since all the high voltage components will be located beneath the secondary
>how do you shield the power wires between the control panel and the NSTs
>from ground strikes?

I use line filters and a LOT of MOVs and some "hope":)

http://hot-streamer-dot-com/TeslaCoils/MyCoils/SmallCoil/small_ACwiring.jpg

>
>I should think the addition of a large toroid would yield larger sparks.
>Where can one purchase a 24x12x6 spun aluminum toroid? How much should I
>expect to spend?

Ask around...

>
>
>All suggestions welcome, I prefer to stand on the shoulders of giants.

:-))

Cheers,

	Terry

>
>Thank you!
>
>Dave
>
>
>=========================================
>Dave Kyle
>Austin, TX USA
>Email: dave-at-kyleusa-dot-com
>