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Old 20th July 2013, 07:49 PM   #151
Einric is online now Einric  United States
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I'm using Fairchild GBPC3506.
I don't see how it is sag.
My traffo is at 18.3V, that is well within specs and I'm only losing .6V through the CRC.
Since this is all Class A and these are idle readings I just don't see the sag anywhere outside the rectifiers.
Is it possible I have bad rectifiers?
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Old 20th July 2013, 07:50 PM   #152
Einric is online now Einric  United States
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Gyuri...what is your total current?
It only looks like I'm 1V behind you and I'm very heavily biased (@350mV) for an F4.

Last edited by Einric; 20th July 2013 at 07:57 PM.
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Old 20th July 2013, 08:00 PM   #153
Gyuri is offline Gyuri  Hungary
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Wait a minute, I must measure it before.
My trafo is said to be 750VA.
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Old 20th July 2013, 08:04 PM   #154
Einric is online now Einric  United States
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My 12 FET's are pulling 9A.
All in all though I don't think I'm far enough off to worry about this.
I guess so long as I don't swing to the rails I will be fine.
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Old 20th July 2013, 08:05 PM   #155
Gyuri is offline Gyuri  Hungary
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For a single supply line it is at about 1,6A
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Old 20th July 2013, 08:07 PM   #156
Gyuri is offline Gyuri  Hungary
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Quote:
Originally Posted by Einric View Post
My 12 FET's are pulling 9A.
All in all though I don't think I'm far enough off to worry about this.
I guess so long as I don't swing to the rails I will be fine.

I also thinks so.
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Old 20th July 2013, 08:27 PM   #157
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18.3V x 1.3 for Class A, yields about 23.5V. Figure in a small amount for drop across CRC and I would bet difference is due to transformer. Antes have shown in some threads slightly more sag. Either way, it should not be a big deal if its not leading to noisey PSU.
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Old 20th July 2013, 08:40 PM   #158
Einric is online now Einric  United States
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Nope, This thing is just WONDERFUL.
I just upped the bias from 300 to 350mV just for kicks.
My highest middle pin temp is only 51C, my fans are doing a fantastic job keeping this thing cool.
I have finally gotten a hold of some 14V Zeners to run each pair of fans from, they are inaudible from 3ft. away.
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Old 20th July 2013, 08:59 PM   #159
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Some what low by data sheet. the bridge should have about 1 to 1.1 volt drop at 12 amps . Thus 18.3 (secondary voltage) times 1.404( square root of 2 to figure peak to rms ) about 25.7 minus 1.1 (forward voltage drop) is about 24.6 approx .

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Old 8th August 2013, 09:17 PM   #160
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Hi Einric

Thanks for the nice PM !

I have been off the air for a while ...
... but gettin' back into things now.

Nice to hear you like the build & it all went well.

C O O L !

Si.
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