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DRSSTC Spark -O- Matic of doom

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LAN_403

lightlinked

Sun Oct 11 2009, 02:04PM

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

* In progress project
So I moved and my failure SSTC ended up just sitting outside getting rusty, and having this special looking thing not work was getting embarrassing, so I have decided to make it live again by dismantling it and doing it up right. Plus I get to build it as a modern art sculpture for class, take that oil painters. I'm not going for big sparks, I just want it to work and be reliable so I can make it go whenever. Iâ€™m hoping for 2 feet of spark

Itâ€™s based off the logic part of Steve Ward's DRSSTC controller with the TC4422 driver board from the SSTC.

Secondary - 30AWG, 4.5" (11.43 cm) x 21.75" (55.25 cm)
Top load â€“ 11â€ stainless IKEA bowls welded together
Fres â€“ calculated with wintesla ~ 86 khz, real TBD
Primary - no 6 ~ .168"(4.3mm) solid copper ground wire 8" (20 cm) dia, 70Â° conical, up to 10 turns or more
Primary tank MMC - .15 uf CDE 940 3 x 3 MMC
Inverter â€“ full bridge Fairchild FGH40N60SFDTU, 10 x 820uf of snap caps + 4 x 5.6uf EPCOS decoupling caps, 170 VDC for now
Control â€“ primary current feedback, based on Steve Wardâ€™s universal controller

Here it is BEFORE all this

The two halves make a whole. I dyed the PCB to see if it could be done, it can be

the front panel, the toner transfer isn't going well with it so far

testing with a tiny setup. I accidentally had solder bridging one of the GDT secondaries to power on the driver board and when I tried to run it at around 80 volts the IGBT's blew up

my new hotness primary coil former. 1/4" fluorescent red acrylic with polished edges. it was a pain to shove the copper up the spiral

low voltage testing. I loosely tuned it by running it CW @ 12 volts with a little light bulb limiting the input current while watching the secondary noise on the scope while sliding the tap around the coil. wintesla said 10 turns but ended up tapping @ 5. I'll have to do a more thorough job.

there are some ugly welds to be touched up with some TIG action

Here is me using my favorite tool, the POWER!

I added some hot hinge action so I can fondle the guts

because the primary is bigger than the pointy thingys, i will have to have the coil elevate above them which should also help cancel out any issues with the metal base reacting with the primary magnetics. i still need to make the interrupter in a box and paint the base, since it will rust, put the guts in the base, tune it, etc.

I held a neon tube up to the top load and an arc hit it, went through me and subsequently through the interrupter and the thing stopped sparking. so I poked around with the scope and one of the GDT signals was low so I replaced that igbt with a cap making I guess a 3/4 bridge and a lil spark came back. so now I have to order some more igbts but at least that's all that died, for now. I've been running off that battery back up, you can push the button and it will turn on. And I also have a light bulb in series to limit the current.

while the epoxy was great i must have broken a turn while trying to sand off abunch of the polyurethane. so now i guess i have to make a new primary. i should have used epoxy the first time. i was supposed to demo it the next day but obviously it wont work. otherwise, i painted it hammertone black and made a snazzy interrupter out of aluminum. i want to eventually make an an AVR controlled interrupter.

update 11/10/09

I finally showed this thing functioning in critique. Driver chips were mysteriously dying but luckily I found out there is a local components store so I got replacements that morning. Sparks didn't get all the way to the sword though. Any power past a 6" plume of corona resulted in arc over just above the acrylic tube to the strike rail. then half the bridge exploded. At least I got to show alittle lightning to prove it worked. Maintenance wouldn't give me dead flouro tubes which is what i really wanted to do, hang a bunch of them from the ceiling.

So I added another coat of epoxy and removed the excess primary wire so I could lower the strike rail. I also took the opportunity to coat the current transformers in epoxy.

This is at a really high break rate, in the low KHz range, but it seems to be the only setting that gets long arcs. I'm probably doing another thing wrong.

Killa-X

Sun Oct 11 2009, 04:39PM

Registered Member #1643 Joined: Mon Aug 18 2008, 06:10PM
Location:
Posts: 1039

Second I saw that base I was like 'Holy crap!' at first I thought it was going to house the primary until I saw it. Whats the goal here? Some creepy Halloween setup? :P Making the base like that almost makes it look evil :D Looks good! Keep up the work :)

lightlinked

Tue Oct 13 2009, 12:08AM

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

Thanks! I was going for just a touch of evil.
I tested it again today and I don't know about having the primary over the spikey things. It kind of throws off the proportion/balance. Maybe if I had a toroid instead of a sphere.
I was getting some arc over to the strike ring from some nicks in the varnish so I put the left over acrylic tube over that part and it seemed to suppress the arc over but I could still see corona forming where the ring is grounded. a cool thing would be to have the whole coil inside an acrylic tube, then filling the space with epoxy.

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