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Old 21st March 2013, 04:46 PM   #11
JLH is offline JLH  United States
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Originally Posted by Magz View Post
-My reply, "Hey, it's cheaper than a Corvette..."
I think a number of us on the forum could challenge that assumption.
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Old 21st March 2013, 04:51 PM   #12
Magz is offline Magz  United States
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Originally Posted by Triodethom View Post
Remember no sharp edges . lock up the cats when that thing is on . I like tubelab bit about choke on the ground leg rather than the hv leg . Look at it this way choke inhibit change in current and the current flows in a loop so which side the choke is on does not matter to it's function in that loop. aarl books on hv 3.5k and up in the past have used the choke on the return leg ( at ground ) .
Yup, all solder joints smooth to prevent corona discharges.

Wire for 833 B+ will be rubber insulated high voltage test lead.

I'm even thinking about installing the 833 upside down so that all ultra-HV is completely contained in the chassis.

I'm allergic to cats.

Another trick is to isolate the choke core from ground, but the benefit of having Monolith do a custom job is that they guarantee it will hold up just fine under the pounding. Based on my discussions with Ward, I have faith...he's even crazier than I am! Of course, the chokes and the OPT will be gigantic, so fitting them plus three large power transformers onto a single chassis per mono that doesn't collapse under its own weight will be a trick.

Approximate OPT dimensions: 10"x10"x8"


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Last edited by Magz; 21st March 2013 at 04:56 PM.
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Old 21st March 2013, 05:23 PM   #13
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Distinct warnings from Cree against stacking high PIV Schottky diodes are fairly well known. Stacking the parts seems to lead to cascading failures. Don't do it!
This from a previous post by Eli Duttman here on diy. I've never seen a definitive answer on the stacking of the Cree Sic Diodes.
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Old 21st March 2013, 05:30 PM   #14
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Here's another fairly recent project: Silvercore 833 C
Project 833 C

and the schematics in this page:
http://t.silvercore.de/index.php?833c-amp-3
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Old 21st March 2013, 06:28 PM   #15
Magz is offline Magz  United States
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This from a previous post by Eli Duttman here on diy. I've never seen a definitive answer on the stacking of the Cree Sic Diodes.
Hmmm...haven't seen that before. I'm planning to add 10nF caps across each to ensure proper sharing between them, but I think I'll look a little further into that one. Thanks for the tip.
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Old 21st March 2013, 06:32 PM   #16
Magz is offline Magz  United States
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Originally Posted by korneluk View Post
Here's another fairly recent project: Silvercore 833 C
Project 833 C

and the schematics in this page:
http://t.silvercore.de/index.php?833c-amp-3
Yes, I've seen that site. I believe they are using lower voltage, however; looking at the power supply they have (4) 400V caps, presumably in series, so max voltage would be 1600V.
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Old 21st March 2013, 07:05 PM   #17
Magz is offline Magz  United States
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Originally Posted by Bas Horneman View Post
This from a previous post by Eli Duttman here on diy. I've never seen a definitive answer on the stacking of the Cree Sic Diodes.
An online search didn't turn up any warnings about this phenomenon that I could find, so I sent an inquiry to Cree about it. Let's see what they say.
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Old 21st March 2013, 07:34 PM   #18
Magz is offline Magz  United States
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An online search didn't turn up any warnings about this phenomenon that I could find, so I sent an inquiry to Cree about it. Let's see what they say.
A definitive (and very quick!) answer from Cree:

Due to a negative temperature coefficient on forward current these devices parallel very nicely to multiply current.

This negative temperature coefficient of forward current allows us to parallel more than one die in a package without any unequal current sharing issues.

This behavior is unlike high voltage Si PiN diodes.

However if clients plan to use the SiC Schottky diodes in series to multiply voltage our engineers would suggest adding balancing resistors of a suitable value.

You do want to force voltage sharing among components . You have identified the issue.



So it appears that using them in series is fine if you encourage voltage sharing. I've seen that done in various references using just caps (10-47nF) and caps plus resistors (470K), so I asked them a followup question about which is optimum. I suspect that anything that evens out the voltage distribution will be OK.
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Old 21st March 2013, 08:19 PM   #19
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I suspect that anything that evens out the voltage distribution will be OK.
Makes sense. I'm suprised you got an answer so quickly.
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Old 21st March 2013, 10:56 PM   #20
CV6045 is offline CV6045  United Kingdom
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If I may make a suggestion...why not put the CHOKE in the Negative Leg of you Bridge Rectifier...that way you will not subject it to any High Voltage...it does exactly the same job using it this way without the expense of having a Choke wound to take the pounding
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