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DRSSTC frustration

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Marko

Sun Sept 23 2007, 08:48PM

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

Finally car was out of garage and air chilled enough to work in the garage; I brought the DRSSTC in by first chance.

I was eager to test my solid state variac with it and full of optimism.

I hooked up a snubber choke in series with dimmer, set up all the wiring, shifted the RF ground from mains to water pipe and got ready.
Started carefully dimming up, coil buzzed.

Then dimmer started to violently shift the power level, depending on how far my hand was from it. And even so I couldn't dim to less than 60V because it would turn off. It gives hardly any power at low voltages, and just isn't a good solution for this.

Now what - I carefully ramped the voltage up all to 150V what my choke allowed, and got PUNY 15..20cm arcs and streamers barely visible even in dark. The coil worked perfectly fine for all tests before, OCD worked and ON time was trimmed to about 200us.

I didn't bother to try anything, unplugged the power and sealed the garage. I'm completely frustrated. Where will I get 6 foot arcs? Where is my mind?
Why I came to idea to use those solder-terminal electrolytic caps?

I may tweak it to give 40cm arcs before blowing the IGBT's everybody will stare and say 'wow', then I'l look at sites with coils of same size doing 2 meters and get depressed.
I could just have built a short-stupid normal SSTC for same effect for like 1/10 of work and cost.

In two years I wasted so much (parent's) money into development of these things, and still came nowhere. Other kids get cell phones, PC's and cameras for their birthdays, I got CAPS which never found any use at all. 1:0 for 'other kids'.

The saddest part is how much money I burned into MISTAKES. I was actually buyng handfuls of metalized polyester and ceramic caps to build MMC! Where was my dumb mind?

Why did I order solder terminal litycs when I knew they won't work?

Why did I do all the useless philosophies with gate drive, before figuring out it's ''just easier'' to use UCC's?

I just needed to be impatient.
Sins from the past always have their vengeance.
If I saved all the money I could have it all done now.

Now I bought right caps, but that didin't make the problem gods any happier.

I'm completely frustrated with all I've done on this project. I don't want to put any more work into it when I know I can't help it.
I can get four 100V 21000uF litycs from school if I ask nicely, but I can't risk redesigning the entire internals of the coil. I'l never get a 4700uF 400V cap I designed the bridge for.

I don't have money for a variac, and dimmers I built were complete waste of time and $$.

I don't want to bring the BORROWED scope to garage, I don't want to move it at all since I'l break it sooner or later.

I don't know if the coil is in tune at all. I'm on last primary turn because I had no more copper pipe. Can't add additional string of caps because tank impedance is alarmingly low.
Can I mock up some wire to get additional turn or two? I don't even have any trashed thick wire I can cut up.
Can I get more desperate than this???

Unless god is going to sell me an oscilloscope, variac, large lityc, PCB's, heatsinks, a handful of IGBT's, 10m spool of copper pipe and SHIPPING for $50 I don't know what to do next with this thing. :(

*cries*

Shaun

Sun Sept 23 2007, 08:52PM

Registered Member #690 Joined: Tue May 08 2007, 03:47AM
Location: New Jersey, USA
Posts: 616

wow.

vasil

Sun Sept 23 2007, 09:48PM

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

Calm down, you are probably out of tune.
Sometime the big results are not present at first time, you have to tinker a bit (it's the best part in coiling, IMHO). And why do you want 6 feet sparks? 40 cm are not enough? :)

Steve Conner

Sun Sept 23 2007, 09:55PM

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

Could be worse, at least you didn't spend it all on drink :P

Reaching

Sun Sept 23 2007, 10:08PM

Registered Member #76 Joined: Thu Feb 09 2006, 10:04AM
Location: Hemer, Germany
Posts: 458

yeah, thats the difference between theory and practice. dont bother with formulas and calculations. try it out! play a bit

im a bit confused about your money problems. why building dimmers and other solid state "waste" when a variac form ebay is to get for a few bucks. even a 4700ÂµF lytic is worth maybe 5$ on ebay, can i sell you some :P shipping costs would be twice the costs of the cap,lol.

everyone here who build drsstc had problems somewhere. everyone here blew up hundrets of $ for its hobby like me, you and all the others. i really dont want to think about what huge amount of money i spent over the years into my projects.

Hazmatt_(The Underdog)

Sun Sept 23 2007, 10:19PM

Registered Member #135 Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735

Take a break, then come back to it with a clear mind.

Not everything is going to be a success on the first go-around, its part of learning.

Steve Ward

Sun Sept 23 2007, 11:25PM

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

Hey, i use those stupid solder terminal caps on my smallest DRSSTC, and they work ok. You should be able to get some promising results with what you have. I think you are probably just not tuned up properly. Can you possibly set up a CT with your scope and take a pic of the primary current waveform? Then maybe i can suggest some tuning based on the shape of the waveform.

Anyway, cool off a bit. This stuff can be very frustrating if you allow it to get to you so much. Just think of how many experience points you will have gained by struggling through this project.

As to buying the "wrong parts". Ive done that a number of times... but you would be amazed at how often i actually go back and use those parts that i thought were useless. For example, i accidentally ordered some 74HC147s (not 14s) and threw them in a drawer (since when would i need a 10 to 4 priority encoder?). Well... a few years later i ran into a problem where that was in fact exactly the part i needed. Ive also mistakenly bought many SOIC parts, but now they are completely useable with my new PCB fab methods. So keep with the hobby long enough, and those ceramic and polyster caps will show some use somewhere (ceramics are pretty good for low inductance snubbering, polyesters are good for any AC application that isnt too high of current).

BTW, seeing coils that outperform my own doesnt depress me, it inspires me to do better... i hope you can keep the same mind set.

Sulaiman

Mon Sept 24 2007, 12:25AM

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

Marko, I have a good idea how you feel

for a long time I renamed my DR-SSTC as SD-SSTC ... Semiconductor-Destroying (or Soul-Destroying) SSTC
I had to stop for a while to save my sanity and whatever little spare cash I had (negligible).

I got lucky - Avalanche gave me a working 'scope and things got better from there on, (Thanks again Avalanche)
lots of scavenging later things are looking better.

Looks to me like you've got a basically good setup
relax for a while,
borrow the 'scope and use it (for a while) ONLY for low power testing
(pri - sec resonance, low-level signals etc.)
You WILL get there eventually.

Good Luck - stay cool and keep on coilin'

Dr. Drone

Mon Sept 24 2007, 12:37AM

Registered Member #290 Joined: Mon Mar 06 2006, 08:24PM
Location:
Posts: 1673

Bennem

Mon Sept 24 2007, 07:28AM

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

Hi Marko,
I understand your frustrations especially when one happens to seem to go two
steps forward then four steps back.
I would advise that you listen to the replies that folks have given,
and take some time off this project and come back to it with a fresh approach.
I have used four 470uf soldered type caps in parrallel for my second DRSSTC, taken from
TV sets, and they work fine, so perhaps play around with tuning a bit more?
I think we've all had 'splatterd' loads of silicon at some point in our projects!
It took me just over a year to get my first DRSSTC parts, and still turned to drink!....lol
so...cheer up!...you'll get there!!

Mel

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