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Old 13th July 2007, 05:55 PM   #101
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If you're talking about the 2-F boost converter, look at post #35, this thread.
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Old 13th July 2007, 06:05 PM   #102
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Hi

What that...how did I miss that. Anyway thanks. Maybe you can tell why did you use what switch, what voltages do you get?
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Old 13th July 2007, 06:26 PM   #103
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I chose the MTP75N06 because it has only 9mW Rds(on), can pass 75A thru its drain, and I had alot of them lying around. I also had the SMT version of them, if I wanted to downsize the circuit.

When switch S1 is closed, V(out) is ~16V, and when it is open, V(out) is ~20V. Guy I did it for needed compatibility with both his laptops.
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Old 7th August 2007, 06:21 PM   #104
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so i am trying to get rid of huge spikes at turn off on kampenens,
i have rewound the transformer and am using 216 of number 36 for my windings?

jimbo
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Old 8th August 2007, 04:44 AM   #105
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Let me see if I understand this right: You're using 216 strands of #36 AWG wire? OK, That should do fine (I assume this is your version of Litz wire?)

Not sure why you're getting huge turn-off spikes. Might want to check your leakage inductance, this is usually the cause.
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Old 8th August 2007, 11:09 PM   #106
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this is some wire i got from space junk in orlando.
it is already sort of twisted slightly.

i have it on a large e-e core.

i have to look closer when i get back in town.

thanks
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Old 20th August 2007, 04:03 PM   #107
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Default turnoff spike

sooo i am using schottkies for the mosfet protection and schottkies for the rectifiers on the secondary.

should i be using ultra fast or fast recovery types? i am operating around 150khz......
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Old 30th August 2007, 01:05 AM   #108
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Schottkys should be fine, especially for the output rectifiers because of their lower forward voltage drop (very important for high-current outputs). A while ago, I found some Schottkys with a 200PIV rating. A couple of years ago, I had heard of some 600V Schottkys, but nothing since.
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Old 31st August 2007, 03:09 AM   #109
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i think i have too many turns on the transformer. i am going to recalculate and see if i can get that pesky spike down to an acceptable level.

i was looking at maybe adding a lossless snubber........
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Old 1st September 2007, 05:40 PM   #110
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Couple o' threads on that subject going on right now. Less turns to get rid of the spike might sound like a good idea. I would look at either Brown, Chryssis, or one of the NSC or ONSemi App Notes.
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