* Original msg to: Lisanap-at-cats.ucsc.edu

 MN> The DC transformer I mentioned in my previous post is rated 
 MN> at 1.5 MA. It is set up with a complete control circuit, 
 MN> including a switch, a small variac, a meter, and RF chokes and 
 MN> bypass caps across the primary and ground lugs.  The primary is 
 MN> 118 VAC, 50-500 CPS.  I can make a Jacob's ladder from this?  
 MN> One side + and the other - ?  If that works I expect it would 
 MN> require a dedicated ground or could it be filtered back into  
 MN> the house ground?  

Oh, you did not mention before that this was a DC power supply. 
While it is possible to make a Jacob's Ladder from this, I doubt
if the secondary amperage is sufficient to make it decent. I wonder
if there are ideas from anybody else on what this might have been, or 
what it can be used for?

 MN> What I have:

 MN> Power supplies - 15/60 (1), 12/60 (1), 12/30 (2).  Right now 
 MN> I have the 15/60 hooked up to the tank that isn't working. Think 
 MN> I'll swap it for the  12/60 to keep from taxing the Caps - six 
 MN> Sprague hockey pucks, .004, 30KV.  Using 4 of these in parallel 
 MN> in the current tank. 

These are really very poor tank circuit capacitors. They get hot,
they are low Q, and they fail under pulse excitation. They are the
best bypassing capacitors I have ever used when placed in series.

 MN> I am a little cloudy on how these operate in series. If caps are 
 MN> in series do you get more voltage rating with the same capaci-
 MN> tance as a single, (I'm assuming identical caps)?  

No, voltage rating goes up, capacitance goes down. Two of these 
.004 uF -at- 30 kVDC caps in series will withstand 60kVDC with a com-
bined capacitance (in series) of .002 uF. Three in series will 
withstand 90kVDC with a capacitance of .0013 uF, four in series 
= .0009 uF -at- 120kVDC, five in series = .0007 uF -at- 150kVDC, six 
in series = .0005 uF -at- 180kVDC. 

 MN> And in a balanced tank config do I use 2 in parallel on each 
 MN> side of the primary or do I need 4 on each side? My guess is 4 
 MN> on each side. This would maintain the original capacitance of 
 MN> the "unbalanced" circuit. It would balance the circuit and also 
 MN> increase the voltage capacity of the caps (tank) as a whole. 
 MN> (I hope you can understand this what I'm trying to get across. 
 MN> I haven't figured out how to edit this yet).

Not to worry about the computer skills, they will come, and so will
the coiling skills. But you don't want to start out with the balanced
circuit right out of the gatehouse. The kickback from the balanced 
circuit will eat those DC rated Sprague doorknobs for breakfast. 
Besides, you will need all of those doorknobs to bypass some of that
kickback to protect your neons, so you won't have any main tank 
circuit capacitors...

 MN> Gaps - 4 tungsten-faced gaps from arc welders. They are mounted 
 MN> in Al clamps with lots of cooling fins. The faces are 3/8" dia.
 MN> They are in series and set at .03" right now.

These are really excellent electrodes for main system spark gaps, and
are readily available. They are manufactured commercially for arc
initiators in TIG welders I believe. They are flat tungsten plates a
couple of mm thick that are bonded to a heavy steel slug which really 
sinks the heat. I see you have also mounted the electrodes in finned
heat sinks for long run times. How about giving us a brand name, 
address and part number for these? This would be a good addition for
my Tesla References file.

 MN> Primary - 8 turns of 1/8" copper tubing in a flat spiral. I take 
 MN> it this is too small?  I plan to upgrade this.

Yeah I would do some more work here. The conductor is too small in 
diameter and too short. Try 60 feet of 3/8 inch soft copper tubing
on a new saucer type coil form.

 MN> Secondary - 2" by 15" of #22 magnet wire (Belden), which comes 
 MN> out to 550 turns. The ratio is way off and the wire length too 
 MN> short, I think. 

Yeah, this secondary is a little messed up. Way too skinny and long,
with dimensions similar to a paper towel center tube :-( Not enough
turns, not enough diameter, the only thing really correct was the
proper gauge of wire was used... Not that that helps much. 

 MN> I have a 4" diameter lexan tube standing by that I would like to
 MN> start from on this next attempt. My existing secondary has a 1 
 MN> 3/4" by 7" Al toroid.

Lexan (polycarbonate) puts PVC drain pipe to shame when it comes to
RF losses. This is pretty good coil form material here. Give us
some thoughts on the planned coil specs for this form.

 MN> My goals are to start a larger coil with higher Q, and rework the
 MN> existing one to see what I can get out of it. If I beef up the
 MN> primary and change to a saucer config? Or is the secondary size 
 MN> ratio too far out? 

You need to retire the previous coil systems, and build these new
barn burners from scratch.

 MN> I noticed all the toys you have in your garage. I hope you did not
 MN> lose anything in the flooding.

I was within a matter of weeks of having ground broken for the new lab.
Plans were drawn up at a reputable architect, land was picked out with
options to purchase pending bank loans, bank was ready with the cash,
my 20% was in hand, and it began to rain, and rain, and rain. Then
the levy broke near the land where I was looking to build, next all
new construction was banned, then the building codes and insurance
requirements were changed.... I lived on high ground, it was just the
lab that would have been endangered.

 MN> I'll be sure to get some specs on the coil that I saw the other
 MN> day and let you know. I should have posted this to the mailing 
 MN> list also, but I keep hitting the reply command straight back to 
 MN> you.  Mark R. Napier  lisanap-at-cats.ucsc.edu

Oh, it will all get forwarded to the group. You should see it all
over again Monday or Tuesday.

Richard Quick

... If all else fails... Throw another megavolt across it!
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