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Requesting Help In Maryland

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LAN_403

HV Enthusiast

Wed Mar 13 2013, 01:10PM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068

Really nice pics there! Thanks for sharing! From everything you describe it appears to be just a tuning issue or phasing issue (the direction with which the primary 12 AWG wire passes through the current transformers.

From my tests of both your microBrute driver board and the modulator, they both performed properly and tested properly.

Deodanth

Wed Mar 13 2013, 01:57PM

Registered Member #9471 Joined: Thu Jan 10 2013, 09:17PM
Location: (39.41895551215511, -76.29627227783203) Grid square:FM19UK
Posts: 23

I discovered another problem... my initial tests of the toroid showed conductivity good but in troubleshooting ive tested several points around the toriod and found inconsistencies. I think I'm not getting good conductivity through the adhesive as described in EVR's instructions
I think I'm gonna take the multimeter to home depot and test some tape from adhesive side to shiny side before I buy it...

HV Enthusiast

Wed Mar 13 2013, 07:37PM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068

Actually your toroid should be fine. At RF frequencies and high voltage, the toroid will appear perfectly conductive. If you are using regular hardware store aluminum tape with adhesive backing, just coat the toroid and use thumb to smooth it all out. It will be fine.

Deodanth

Wed Mar 13 2013, 09:11PM

Registered Member #9471 Joined: Thu Jan 10 2013, 09:17PM
Location: (39.41895551215511, -76.29627227783203) Grid square:FM19UK
Posts: 23

Ok new IGBT's arrived and are installed ..low power test results in resonance.

High power test results in red "overcurrent" LED lighting up and the resonance noise at 50% PW sounds tinny like something stuck in an old metal fan.

EDIT:
And another blown IGBT. Acting on previous advice and since I ordered 4 I replaced them both.

Awaiting advice

HV Enthusiast

Wed Mar 13 2013, 09:21PM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068

Hmmm . . . I would say something sounding tinny like something stuck in a fan would probably be a good description of what a break-out would sound like. Its not a very soothing noise.

Deodanth

Wed Mar 13 2013, 09:44PM

Registered Member #9471 Joined: Thu Jan 10 2013, 09:17PM
Location: (39.41895551215511, -76.29627227783203) Grid square:FM19UK
Posts: 23

Edited my above post.

Does the overcurrent light help diagnosis?

Physics Junkie

Wed Mar 13 2013, 10:42PM

Registered Member #7267 Joined: Tue Oct 16 2012, 12:16AM
Location: Detroit, Michigan
Posts: 407

Hi, the overcurrent trip can be a good thing. It's hard to diagnose without seeing a video of operation. (But of course, dont waste your IGBT's on making a video). Assuming that the breakout point is positioned on the side of the toroid, are you getting arcs to objects? I see you put a step stool next to the coil, so I assume it is there for just that. But are the arcs hitting the secondary or primary at all?

Deodanth

Wed Mar 13 2013, 10:49PM

Registered Member #9471 Joined: Thu Jan 10 2013, 09:17PM
Location: (39.41895551215511, -76.29627227783203) Grid square:FM19UK
Posts: 23

PJ,
Hi, No didnt see any output arcs. I ran electrical tape over the part of the secondary where the patch was to protect it so I could not see what was going on under there, but thinking that could be a problem. Liam and my wife are right now re-winding the secondary.

Shes much more obsessive about things and will wind the coil cleanly I think.
Dan emailed me yesterday and suggested a new coil so thats a step we are trying.
I did do a low power test and got resonance "Buzz" with no power applied to the coil and the new IGBTs so I'm hoping that indicates the board is operating properly. When they get done winding the coil I will put things back together and start voltage testing from scratch.

Thanks for the reply.

Physics Junkie

Wed Mar 13 2013, 10:56PM

Registered Member #7267 Joined: Tue Oct 16 2012, 12:16AM
Location: Detroit, Michigan
Posts: 407

Like ben mentioned before, make sure you insulate the secondary when you are done winding it. for a coil that size, a can of clear coat enamel spray should do just fine and is inexpensive. polyurethane varnish is ideal. where is the 'buzz' coming from?

Deodanth

Wed Mar 13 2013, 11:08PM

Registered Member #9471 Joined: Thu Jan 10 2013, 09:17PM
Location: (39.41895551215511, -76.29627227783203) Grid square:FM19UK
Posts: 23

Low power test for resonance.
I recorded the high power test on a different camera so I'll have to figure out how to upload it.

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