oneTesla - a small single-board DRSSTC / Projects / Forums

Forums

4hv.org :: Forums :: Projects

« Previous topic | Next topic »

oneTesla - a small single-board DRSSTC

1 2 3 4 next last

Move Thread

LAN_403

Dr. ISOTOP

Mon Jun 11 2012, 03:52AM

Registered Member #2919 Joined: Fri Jun 11 2010, 06:30PM
Location: Cambridge, MA
Posts: 652

12/28/2012:

Support our Kickstarter Campaign!
Our webstore (in progress) can be found here

*Coil specs*
*~220KHz Fres
*2.5x10" secondary, 36 AWG with 2x8" topload
*Peak current: 350A
*Max spark length (ground strikes): 23"
*400VDC doubled variac feeding a half-bridge of FGH60N60SMD's
*14AWG primary, 6 turns on 3.5" former, 68 nF 3KV CDE940 series tank cap

12/09/2012:

Better video footage, with a spun toroid:

For y'all people who are building this from eBay boards, I have a bit here about things you should and shouldn't do.

7/15/2012 UPDATES:

This project has grown a lot since it was first conceived. Performance is now up to about 2', from a 10" secondary, using FGH60N60SMD IGBT's.

pics:

There's a short run of professionally fabbed boards for sale here to help fund further development. Kramnik and I also have more complete accessories, a kit, and a polyphonic interrupter in the works.

Critical specs of the new coil:

*~220KHz Fres
*10" secondary, 36 AWG
*Peak current: 350A
*Max spark length (ground strikes): 23"
*400VDC doubled variac feeding a half-bridge of FGH60N60SMD's
*12AWG primary, 68 nF 3KV CDE940 series tank cap

If you want to assemble your own from an eBay board get the Eagle files here.

-----------------------OLD INFO BELOW--------------------------------------------- -
Inspired by EVR's microBrute, I decided to route a DRSSTC onto a 4"x6" board.

The result:

Half the credit for this project goes to Daniel Kramnik, who built the coil in the video above using his revision of my design (which includes an optical interrupter).

The driver:

Low-power (~50W) sparks:

Critical coil specs:

Driver: half-bridge of FGH60N60SMD IGBT's
Primary: 4.5 turns of 14 AWG on a 3.5" PVC former
Secondary: 2.5x7", 36 AWG with a 2x7" topload. Resonant frequency is ~320KHz
Tank cap: CDE940C30S68K-F, 0.068 uF@3KV

The video is running at 250A with 30uS on time and 340V bus voltage.

Power figures:

4"@30W, 5uS on
6"@80W, 20uS on
10"@140W, 30uS on

(all numbers at 200 bps)

Blog post about it here:

Board file for the (old) version of the coil:

Digikey BOM for everything except the transistors:

Thomas W

Mon Jun 11 2012, 05:50AM

Registered Member #3324 Joined: Sun Oct 17 2010, 06:57PM
Location:
Posts: 1276

Nice!
that is a really good idea, and design :D

lightlinked

Tue Jun 12 2012, 06:06AM

Registered Member #2087 Joined: Tue Apr 21 2009, 08:32AM
Location:
Posts: 115

thats pretty awesome. how long of a streamer can you get in free air? what does the interrupter look like? is over current protection not needed in little coils?

Dr. ISOTOP

Tue Jun 12 2012, 03:05PM

Registered Member #2919 Joined: Fri Jun 11 2010, 06:30PM
Location: Cambridge, MA
Posts: 652

lightlinked wrote ...

thats pretty awesome. how long of a streamer can you get in free air? what does the interrupter look like? is over current protection not needed in little coils?

I can get 6-7" in free air; note that the entire coil floats, so this may be limiting my streamer performance.
The interrupter is microcontroller with optocoupled output.
I've yet to need OCD on this coil. The bridge seems to hold up fine during ground strikes.

Josh Campbell

Tue Jun 12 2012, 07:09PM

Registered Member #5258 Joined: Sun Jun 10 2012, 10:15PM
Location: Missouri - USA
Posts: 119

Ha, great design. Good choice of song too, I like how the music's pitch affected the resonance and thus the output. Do you input unmodified (audible range) music or do you modify it to fall in a specific tonal range?

Dr. ISOTOP

Tue Jun 12 2012, 07:14PM

Registered Member #2919 Joined: Fri Jun 11 2010, 06:30PM
Location: Cambridge, MA
Posts: 652

2bytes wrote ...

Ha, great design. Good choice of song too, I like how the music's pitch affected the resonance and thus the output. Do you input unmodified (audible range) music or do you modify it to fall in a specific tonal range?

The pitch affects the break rate, hence total power throughput and spark length.
I believe this is with unmodified music; the interrupter is Daniel Kramnik's design, so we shall wait for him to answer.

Ben Solon

Tue Jun 12 2012, 08:34PM

Registered Member #3900 Joined: Thu May 19 2011, 08:28PM
Location:
Posts: 600

if you ground it you not only will get longer streamers, but the audio will stop crackling too. that's because the crackling is caused by the streamer having trouble breaking out. notice how you get perfect audio quality when you get "ground" strikes.

but on another note, very nice! i saw this somewhere a couple days ago, but good to see you have finalized it.

Steve Ward

Sun Jun 17 2012, 06:55PM

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

Excellent IGBT choice

. I say this because i use that part for some other projects of mine and im very happy with them.

Have you reached a point of part failure? or have you simply limited the on-time and current to be "safe"? I suppose your single MMC cap can only take so much as well.

Maybe also consider using 2 separate heatsinks so that you can directly mount the IGBTs and avoid thermal resistance of an insulator. At least i'd look at that for maximizing the performance of those parts.

Very nice work, either way.

Dr. ISOTOP

Sun Jun 17 2012, 10:22PM

Registered Member #2919 Joined: Fri Jun 11 2010, 06:30PM
Location: Cambridge, MA
Posts: 652

Steve Ward wrote ...

Excellent IGBT choice

I've yet to reach IGBT failure on the 60N60's; on the old bridge (FGH40N60SMDF) it would silently die at about 300A. Been meaning to push the coil to the point of destruction, but I'm out of 60N60's for now

a few transistors gave their lives due to human error.

Here's a new video with streamers; tying the secondary base to earth ground worked wonders. I also added a low-pass filter (R and C in parallel to ground) on the feedback pin on the 7414, which got rid of the static-ish noise in the first video.

Three coils are better than one, right?

Daniel Kramnik

Fri Jul 13 2012, 02:26AM

Registered Member #3885 Joined: Sun May 15 2011, 12:47AM
Location: Newton, Massachusetts, United States
Posts: 94

Update!

Bwang sent out a double-sided version of the board - all noise issues are long gone, and the performance is even better with longer on-times and looser coupling.

Specs. are ~2 feet spark length with 300 - 350A primary current at 400Vbus and a 2.5" x 10" secondary.

1342146396 3885 FT139829 1tesla Myro Board

1 2 3 4 next last

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob