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Re: Big SISG Coil First Light - New Charging Circuit Works Too!!

Original poster: Vardan <vardan01@xxxxxxxxxxxxxxxxxxxxxxx>

Hi Bart,

Bare MMC caps with the bleed resistors are pretty fragile especially if you use them for testing and such as stand alone caps. I have put them in PVC tubing with end caps before like this:




1/4 inch brass bolts and wing nuts make it very easy to connect and they are practically indestructible.

However they tend to "rattle" since the guts are just floating around in there. So this time I tried foam:


It is available at any hardware store for about $5. It works great, drys fast, does not smell... You don't want to get it on anything valuable since it will stick and never come off so just put down plastic sheet. It appears to be "Gorrilla Glue" under pressure and it expands once in the air. You just let it dry overnight and saw off the excess. It does not stick to the plastic on the applicator tube so you can ram a big wire down the tube and pick it out of the handle and can tip and reuse it all you want (let it dry first). You need safety goggle since it is real bad if you get it in your eyes. You might want to try it out first since it is sort of odd stuff to use at first. I covered the outside of the box with plastic and used masking tape to keep it off the pretty parts.

One could use any "right size" plastic container for the caps. You could put the foam side down or cover it as you want. The foam is not a great insulator since it is mostly air but it does not short anything out. The foam will burn if set on fire, but mildly.

So I really like it!! I wish I had put all the caps into one box instead of two though. I should have taken pictures...



At 08:06 PM 8/8/2006, you wrote:
Hi Terry,

Wow, neat!

I wanted to comment on your cap cosmetics. That is just - cool. So, you've got basic CD's inside a square plastic tube filled with foam. Who would have thought? I was just getting over being a little p***** off with myself (I blame you). You were smart enough to build this nice square cabinet with your SISG coil and I built this round thing-a-ma-jig. Round sucks! Next time, I'm going the "Terry Route". Low and behold, you now throw this new cap containment system in front of me!!!! I'm back to being "p***** off" at myself - again!!!

All kidding aside, great job! Your SISG is just what I need to get started into the SSTC world of coiling. Thanks for all the pics and documentation.

Take care,

Tesla list wrote:

Original poster: Vardan <vardan01@xxxxxxxxxxxxxxxxxxxxxxx>


I finally got the larger SISG coil's electronics going today. It works good!!! :-))

This coil uses a new SiSG charging circuit shown here (probably work for standard gap coils fine too):


The charging circuit gives the coil a fairly surprising BPS range. It starts at about 70 volts at roughly 60BPS and goes "up" from there. Its nature is like that of an async system. It seems to work pretty much as predicted. I did not spend much time on models for it yet until I could test to see if it worked at all.

There are pictures here:





There is a VCD format movie here:


If you can't get it to play there is a rougher but more basic MPG here:


If it is real busy, try back a bit latter.

The capacitors are MMC in a length of plastic gutter pipe. I could have put them all into one the same size. I may get more caps and do that just to save room in the final coil. I filled them with polyurethane foam which works well. I will hard epoxy the ends someday...

The coil itself is just the old DRSSTC step up for now too.

The SISG is Mark Dunn's board which works fine. It can easily hit 24 inches. I have into measured much yet but the new charging circuit should have a very good power factor and all. The resistors burn off heat but it will have a fan ;-)) That is a small cost for the simplicity and I don't think it can be blown up. The SISG IGBTs seem to run cold. I will have to test it to see if I might want to go to 225W resistors just to keeps things cooler.

The bang power is 1.54 joules at say 185 watts at 120BPS. It seems like one could very easily scale it up but I have not gotten more IGBTs yet to fill more boards. The 237.5nF primary cap seems to be a nice balance of primary peak current, energy, Fo, and power. But there or probably things that could be optimized since the resistor values were pretty much a guess.

But the main thing is that the charging circuit does actually work very well!!!