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hvguy

Mon Mar 26 2007, 07:03AM

Registered Member #289 Joined: Mon Mar 06 2006, 10:45AM
Location: Conroe, TX
Posts: 154

Hi All,

This is the first stage of testing on a project I started almost a year ago. My original goal was to get this system up and running in about two months but that whole â€œlifeâ€ thing got in the way and I ended up moving to NC. This meant dismantling the project, transporting the 16â€ x 84â€ secondary, and storing the equipment until the weather was good enough to resume work. Unfortunately I moved from my shop in Houston, which had a 20â€™ ceiling, to a garage in NC that has an 8â€™ ceiling. This made working on the 7â€™ tall secondary somewhat interesting. Ok thatâ€™s the back ground, on with the specs:

Sec â€“ 16â€ x 84â€ wound 82â€ with 20ga 600V PVC wire (Yes, itâ€™s orange, you've got to use what youâ€™ve got)

Toroid â€“ 16â€ x 64â€ made of several 4â€ corrugated drain pipe sections covered with AL tape. This toroid is not nearly as nice after the moveâ€¦

Pri â€“ 3 turns of 5/8â€ copper tubing on 1â€ Phenolic supports

Cap - .66uF 8KV CDE MMC

IGBTs â€“ two Powerex CM1000U-34NF in a full bridge

Envelope â€“ 250uS 120Hz

Ipk - About 2KA. I have not taken an offical measurement yet.

The logic is nothing special, just your typical 15V parts, which I chose for better noise immunity due to the higher rail voltage. Yes, they are not quite as fast as the 5V parts but the delay in negligible in this case due to the relatively slow IGBTs. The oscillator shown in the schematic is my on board test oscillator and was used for this run. I have another, more advanced, fiber optic controller in the works for future use. Fres is about 69KHz.

As for the gate driverâ€¦ As far as I know everyone using bricks is driving them with some derivation of Steves discrete driver. This is an excellent driver but I just canâ€™t get past having all that silicon to fail/trouble shoot/replace if something goes wrong. I decided to go with an off-line gate driver and larger GDT. This is actually quit simple and has proven reliable thus far. It should be noted that the secondary needs to be either shielded or well separated from the primary of the main GDT or spikes of large enough magnitude to damage the driver IGBTs can be coupled through capacitively. Hereâ€™s the schematic; those of you that know me may have seen this at the cheese head thon:

After waiting for so long to fire this coil up I was going to take advantage of any opportunity to run I could get. In this case the conditions were almost perfect, had it not been for the nearly constant arc eating 11mph winds. So while the 24â€™ I was hoping for didnâ€™t quite happen...yetâ€¦ Iâ€™m still happy with the 18â€™ that was had at about 600VDC and 17KW (measured on the AC line side with a RMS true power meter, PF was .7). Here are a few pictures and a video. The strike out to my hitch lift is +16â€™.

The coil is not yet fine tuned and the runs were kept short so as not to piss off the neighbors at 9pm on Sunday night. I canâ€™t wait to see what it does without the wind and at full powerâ€¦.

I will post more as time permits.

Aron

thedatastream

Mon Mar 26 2007, 10:20AM

Registered Member #505 Joined: Sun Nov 19 2006, 06:42PM
Location: Yorkshire!
Posts: 329

Very, very impressive, that's a nice piece of engineering - congratulations.

I look forward to seeing the results on a really good run.
I think I shall give up coiling and go and live in a hole somewhere

I would also be interested to see your primary fullbridge and decoupling layout for something of that power.

Give yourself a pat on the back
James

p.s. I wonder what the driver of that car thought?

Steve Conner

Mon Mar 26 2007, 11:09AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Awesome! Madness!

Bennem

Mon Mar 26 2007, 11:55AM

Registered Member #154 Joined: Sun Feb 12 2006, 04:28PM
Location: Westmidlands, UK
Posts: 260

Ermmm.....what can i say , but,....... WOW !!!

ps....lol at driver deciding to turn right.

Andrew L.

Mon Mar 26 2007, 12:35PM

Registered Member #515 Joined: Sun Feb 11 2007, 02:06PM
Location: Slovenia/Ljubljana
Posts: 94

Holy mother of all Tesla coils

It makes my puny Tesla coils look so small and insagnificant

Marko

Mon Mar 26 2007, 12:40PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

Holy Thor! The best owned picture ever:

And.. you are driving CM1000's with a GDT? It must be a monster

..I don't know what anymore to say!

Sulaiman

Mon Mar 26 2007, 01:14PM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

Jaw-dropingly WOW!

Great coil and photo's

Congratulations

vasil

Mon Mar 26 2007, 01:17PM

Registered Member #229 Joined: Tue Feb 21 2006, 07:33PM
Location: Romania
Posts: 506

Cool! Impressive project!

Steve Ward

Mon Mar 26 2007, 04:45PM

Registered Member #146 Joined: Sun Feb 12 2006, 04:21AM
Location: Austin Tx
Posts: 1055

Nice to see that driver work like it *should* this time

.

That toroid is pretty cool looking, and now it explains the toroid on the large SGTC on the hvguy site. Pretty clever, and surely cheaper than getting the *big* corrugated tube (my 9" OD stuff was like 35 bucks).

How can you expect 20' with the toroid only ~10 feet above the ground?! Do you have a taller stand in the works?

Id really like you to take an "official" measurement of the primary current. Last i remember, i was running about 1500Apk for only the 10-12 foot sparks, so 2kA for your 16 foot spark would seem about right.

Oh, and your workspace is really organized

hvguy

Mon Mar 26 2007, 05:34PM

Registered Member #289 Joined: Mon Mar 06 2006, 10:45AM
Location: Conroe, TX
Posts: 154

Thanks for the comments everyone. It's always nice when a project of this scale finally gets off the ground.

Steve, believe it or not all the problems I was having at the thon were because of a half dead UCC part. My gate waveforms were all screwed up which created some odd transits and took out one of the driver IGBTs and fried that sand block. I think the part was dead before it was even installedâ€¦.

It may seem like expecting +20â€™ from a coil of this height is unlikely but I base this off of two things. 1) My 10â€ coil hit 16â€™ and is about 9â€™ tall 2) The longest arc last night was not caught on video but was 18â€™ out to the red cart on the left, so why not another two feet or so. Also, I can raise my toroid up another 12â€ using the all thread it is mounted on.

If the weather holds up I will run again tonight and take a primary current measurement.

Thanks... Itâ€™s not always that clean though, this project took so much space I had to keep it as clean as possible for everything to fit.

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