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Austin

Fri Feb 15 2008, 10:45PM

Registered Member #1169 Joined: Wed Dec 12 2007, 09:16AM
Location: Portland OR
Posts: 251

Wirenut wrote ...

Try to see if John Freau has any toroids or make your own.

John F. is futuret at aol.com - I bought my toroid from him - highly recommended. There are some decent looking 3x12 toroids on ebay

Okay, Austin, I'm getting worried about ya bro.
I haven't heard any progress on the Minibrute in a while.

Don't worry, he hasn't given up - he had mid-terms last week and was busy. I believe he's working on the secondary and interrupter.

I'm going to a friend's house tonight with my coil - will try to get some better and longer video footage and some new pics to post tomorrow!

Wirenut, Ur the MAN!

kg7bz

Sun Feb 17 2008, 05:16PM

Registered Member #1325 Joined: Sun Feb 17 2008, 05:03PM
Location: Lakeside, AZ
Posts: 2

I've built lots of older coils, spark gap, Vacuum tube, now I'm gathering the parts for a DRSSTC using the Mini-Brute design. The one part I'm wondering where to get is the Fair-Rite core for the IGBT grive transformer. It doesn't look like Fair-Rite sells direct from their web site, what's a distributer that sells them?

Thanks for any information,

August

Bennem

Sun Feb 17 2008, 06:38PM

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

I got my Fair-Rite cores from 'bytemark'
just do a google search under type 77 or 78 ferrite cores.
They do small orders too!

Mel

kg7bz

Sun Feb 17 2008, 09:05PM

Registered Member #1325 Joined: Sun Feb 17 2008, 05:03PM
Location: Lakeside, AZ
Posts: 2

Thanks very much! My mind just needed jogging, I've bought from them before. Looks like Amidon also carries them for the same price. Let the fun begin!

August

Austin

Sun Feb 17 2008, 09:10PM

Registered Member #1169 Joined: Wed Dec 12 2007, 09:16AM
Location: Portland OR
Posts: 251

would this make a good variac for the minibrute or should I get something with a bit more amperage?
link

Ultra7

Mon Feb 18 2008, 01:52AM

Registered Member #1157 Joined: Thu Dec 06 2007, 12:11PM
Location: Houston, TX
Posts: 307

I Just bought one of those for my SGTC!!!!
No BS!
Though, I paid 86.55 total for it.
I guess you got a better deal than I did.

Austin

Mon Feb 18 2008, 04:17AM

Registered Member #1169 Joined: Wed Dec 12 2007, 09:16AM
Location: Portland OR
Posts: 251

I didnt buy the variac cause I thought 3amps was a bit low, anyone willing to give some input? how many amps should my variac be able to pump out?

Also does the polarity matter for the mmc board? Ie does it matter which end I hook the output from the half bridge to mmc?

Also does the polarity matter for the current sense transformers? Ie does it matter which way the 8awg cord goes through the hole of those two transformers that hook up to the resonant board?

I had one last question about the "physics of induction". I remember learning about the right hand rule in physics 213 and how that applies to magnetic fields. if your thumb points in the direction of the current and you curve the end of you finger tips, that points the directions of the magnetic field. ......... if this is true than two wires that are "perpendicular" to each other will have a harder time inducing current on one another than if those wires were parallel. if that assumption is correct it will help me lay out my wires in the base of my tesla. Let me know what you guys think.

Wirenut

Mon Feb 18 2008, 06:01AM

Registered Member #141 Joined: Sat Feb 11 2006, 01:14PM
Location: Southern California
Posts: 96

I didnt buy the variac cause I thought 3amps was a bit low, anyone willing to give some input? how many amps should my variac be able to pump out?

That was probably a good idea (not buying). The variac I use is a small 5 amp one that I put a 20A fuse into. I think this is at the minimum limit of what will work, as it gets hot after about a minute of use.

Also does the polarity matter for the mmc board? Ie does it matter which end I hook the output from the half bridge to mmc?

No.

two wires that are "perpendicular" to each other will have a harder time inducing current on one another than if those wires were parallel.

This is correct.

ps... sorry no new pics or vid yet. I am having a problem with my coil that I haven't figured out yet. Output arcs have dropped down to 3 feet initially, and rapidly shrink to two feet. Wall current draw seems excessive. MMC caps seem ok, I think I may have a half-blown IGBT - is that possible?

Austin

Mon Feb 18 2008, 06:32AM

Registered Member #1169 Joined: Wed Dec 12 2007, 09:16AM
Location: Portland OR
Posts: 251

Wirenut wrote ...

ps... sorry no new pics or vid yet. I am having a problem with my coil that I haven't figured out yet. Output arcs have dropped down to 3 feet initially, and rapidly shrink to two feet. Wall current draw seems excessive. MMC caps seem ok, I think I may have a half-blown IGBT - is that possible?

apparently, I did some quick research and found that your not the only one with a "half blown" IGBT... one instance can be found here linky ... its not the exact part, however operating principles may still apply. you should really invest in a strike rail =P

so would a 0-140 volt / 10-20 amp variac work?

Wolfram

Mon Feb 18 2008, 06:48AM

Registered Member #33 Joined: Sat Feb 04 2006, 01:31PM
Location: Norway
Posts: 971

The guy in the forum you linked to is talking about bricks with two IGBTs in each, presumably halfbridge bricks. As I understand it, "half-blown" means that only one of the two IGBTs in the brick is blown.

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