[Prev][Next][Index][Thread]

Re: Scroungein' (fwd)

>From: Tesla List <tesla-at-pupman-dot-com>
>To: tesla-at-pupman-dot-com
>Subject: Re: Scroungein' (fwd)
>Date: Mon, 19 Apr 1999 18:56:21 -0600
>
>Original Poster: Bart Anderson <mopar-at-uswest-dot-net> 
>
>Hi Christopher, I added some comments below:
>
>> Original Poster: "christopher boden" <chrisboden-at-hotmail-dot-com>
>>
>> Due to constant design changes and new ideas....not to mention a
>> through flogging from Sam ;-) we are trying two seperate ideas.
>>
>> Project 1
>> Design Goal: To produce 5' discharge from a 120VAC <20Amp input.
>> Secondary size: 25" X 4"
>> Secondary winding: 26 AWG? (any ideas?)
>> Secondary form Schedule 40 PVC 4" pipe with glued on endcaps
>> Winding method: Lathe....BIG lathe.
>> Primary winding: 1/4" soft copper tubing
>> Primary form: Flat helix?
>> Primary size? Number of turns/spacing????? any ideas?
>> Caps: Where can we get some? What size do we need? How long will 
they
>> last? We need rock-solid-reliability.
>> NST: 15KVAC -at- 30mA
>> Variac: ? what size do I need 20A?
>> Spark Gap:Static (no shrapnell) possibbly the Quick model
>> Torus: ?? biggest possible?
>> Anything else? What am I forgetting?
>
>The secondary sounds ok. The cap size for your xfmr would be about
>0.005uF, and the primary will need about 19 turns. The xfmr at 30mA 
is a
>bit low for 5' discharges. I would consider at least 60mA and make 
the cap
>0.01uF (primary then is about 14 turns). 

I ordered a 60KV .001~.005 Cap from Maxwell. Does the value matter 
exactly? I figured that since people can pull this off with "Beer 
Bottles" I didn't have to have an exact value. I'm hopeing to be able 
to use these caps for both coils, can that be done? I'm also getting 
a BIG pulse cap (think 300 Lbs) for some other work, could that be 
usefull for this stuff as well?

You should then get about 40 to
>50 inch sparks. I would go with a 26pF top capacitance (26" x 4" 
toroid).

We're trying a rather novel idea for the Toroid. A 20" Bicycle wheel 
with the standard aluminum ducting aroung the periphery (like a funky 
tire) It will balance well, be uniform, look sharp, and be easily 
mounted. The question is, will the damn thing work? I dunno, but it's 
worth a shot, and if it doesn't, it won't be an expensive mistake.


>If you need rock solid reliability in a cap, then I would suggest a
>manufacturers cap.
Maxwell is doing a special run for us :-)

 Of course you do realize that nothing is rock solid in
>a TC, especially caps?
I know but if I keep telling myself that I might actually start 
believeing it, I can dream can't I? Do you have any idea how hard it 
is to get Maxwell to donate a whole herd of $3000 caps?

>> Prodect 2
>> Coil Name: Thor
>> Secondary size: 12" X 5' twin secondaries
>> Secondary wire: 18AWG
>> Secondary Form: 2  1X5" Sonotubes 1/4" Cardboard tubes
>> Primary Wire: 3/8" Soft copper tubing
>> Primary Size: ?
>> Primary Form: Flat Helix
>> Power Supply: 20KVA Pole Pig (Supplier?)
>> Spark Gap: 4 Pole Async Rotary in a 1.5" Lexan Enclosure (ideas?)
>> Control Circuitry:?? Ideas?
>> Caps: Big... Ideas? Suppliers? MMC?
>> Possible "Magnifier" setup insted of twin secondaries?
>> Design Goal: Biggest possible discharge:
>
>Now this sounds like a fun project! The sonotubes will work fine. 



Just
>make sure you seal them inside and out. I like to use a thin 
absorbing
>polyurathane to prep the coil, then later use spar varnish for the 
outer
>coatings (flexible and goes on thick). When purchasing the tubes, 
measure
>the diameter because they vary quite a bit from tube to tube. 18awg 
is a
>good size to use for this coil size, but you'll need about 20lbs. per
>coil. If you can get 20lb spools then it will be easy. If not, you 
can
>drill a small hole and run both wire ends inside (sand, twist, 
solder,
>snip, hot glue - works great). Then keep winding. You'll probably 
leave a
>couple inches unwound on each end so you'll end up with about 1260 
turns
>if close wound (56" length).
>
>It's difficult to guess your xfmr voltage/current, so I'll go with a
>standard 16.8kv, 893mA (15KVA). If you matched your cap size to this 
xfmr
>size, then you would need 0.141uF. The problem with this is 40J. Way 
too
>much energy. So you MUST NOT go with a matched xfmr sized cap, but 
with
>something less (way less). I'll cut it down to 12J (still a lot). 
This is
>4 times less Joules and thus 4 times less capacitance. 0.04uF is 
11.3J.
>This would equate to 15.7 turns on the primary. I would go with 100kv
>rated professional caps if I were you. Your cap is going to see 50kv 
quite
>often at full voltage. These are big coils and your talking about 
20KVA
>potential. This equates to big sparks. Really big sparks if it 
doesn't
>burn up first. You'll definately need a high grade rotary gap. 
You'll also
>need to externally ballast the pig with some large inductance. I 
would
>recommend big variacs with this (40 to 50A type). These are not easy 
to
>come by. Also, the 20KVA xfmr is not really necessary since you can 
push
>these transformers quite a bit above their ratings. A 10 or 15 KVA 
will do
>just fine for your set up. The toroid size I would recommend is 67pF 
(12"
>x 63" toroid).
>
>> Both coils will be housed in a dediated "High Voltage" room.
>> Room dimentions : 70' Long X 32' Wide X 23' High
>> Raised wooden floor (concrete floor 3' below for 26' ceiling 
height)
>> can be remooved if needed.
>> Brick walls 3-5' thick
>> Dual RF dedicated grounds to 10' Ground rods on 0AWG ACSR 
conductors.
>> Concrete ceiling with 3' X 6" I-Beams every 3'
>
>Sounds wonderful! I wish I had that kind of space.
>
>> Power supply (Mains): 480VAC -at- 500Amp 3Phase to 100 KVA Stepdown 
(220)
>>
>> Control room will be next to the HV room with interlocks preventing
>> the doors to the HV room being opened while the mains to the TC are
>> energized.
>> Both coils will require a key to arm the system and a button to be
>> held to power the NST/pole pig.
>> Thor will require 2 Keys 6' apart to arm the system and a button to
>> arm the Pig.
>
>Safety will definately be important with these coils. The 2 key idea 
may
>be a bit more than I would go, but hey, to each his own. Whatever 
you do,
>make sure you have a fire extinguisher around, seriously. I keep one 
handy
>when running my coil (12.5" x 44", 10KVA, sonotube coil). As far as
>control panel, I would use a low voltage setup which energizes the 
AC line
>via relays or whatever. The current capability will let you know 
what you
>can do. Make sure you use dual-trip breakers so that both legs of the
>mains break at the same time.
>
>> There may be a Faraday cage in the HV room for viewing, if this can
>> be done with ABSOLUTE safety to persons/ cameras inside...any 
ideas?
>
>I would just stay far far away to NOT get hit. You don't want to get 
hit
>by this coil. A faraday cage is a good idea if you plan to be in 
stike
>range.
>
>Well, I could write for hours but that's all I had in me tonight. 
Lot's of
>good questions. However, I'm better at a piece at a time than all at 
once.
>
>Anyway, best of luck to you,
>Bart
>
>
>



Christopher A. Boden 
The Geek Group 
344 Ionia SW 
Grand Rapids MI 
49503 
(616)-574-4065 
 
The Geek Shall Inherit the Earth! 


_______________________________________________________________
Get Free Email and Do More On The Web. Visit http://www.msn-dot-com