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Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
I've covered output voltage adjustment in my previous SMPS modding threads. As Richie said, it helps if you can do it without changing the gain of the feedback loop, so I do it by injecting an offset into the error amp rather than messing with the feedback resistors.
I think it's important for the +12 and -12 to have the same number of windings on the output choke. You could always replace the +5V winding with thin wire if you're not going to use it, to free up more room. Or remove the +5V output altogether, if you know how to alter the regulation and protection circuits so the PSU will still work without it.
Registered Member #1232
Joined: Wed Jan 16 2008, 10:53PM
Location: Doon tha Toon!
Posts: 881
> Would it work if i put the new -12v winding on a different ferrite toroid?
It will work if you put the other winding on an identical IRON POWDER toroid, not ferrite! I'd guess what is in there is a Micrometals T130-26 or something similar (yel/white colour)
Provided you only intend to draw current between the +12V and -12V rails, cross-regulation is not important. If you intend to load the +12V and -12V rails unequally both windings want to be coupled on the same core.
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ATX PSU question
