Basic transformer question: using half and full secondary at the same time

soapfoot

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Dec 27, 2010
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So I have a pair of these Triad transformers, and I need to make 24V and 12V for two separate supplies (regulated phantom via voltage tripler, and DC heaters).

http://www.mouser.com/ds/2/410/VPT48-520-224312.pdf

Don't ask why I'm trying to do that with this transformer... it was a last minute change of plans and I already have the parts.

Anyhoo, I could hook up the primary in series, connected to 120VAC to give me dual 12V secondaries. 

My question is-- if I connect the two secondaries in series to provide 24VAC for my phantom circuit, I could also get 12VAC from one end and the center tap.

Is there any danger or disadvantage to using half the secondary for one thing, and simultaneously using the full series secondary for another?

Thanks!
 

gemini86

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Sep 22, 2008
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2,476
Location
Eugene, OR USA
Not at all. As long as the current specs aren't overloaded. It's just the same as a bipolar output, but we moved the ground reference from the center tap to the "bottom" output.
 

JohnRoberts

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Nov 30, 2006
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Hickory, MS
No problem in general as long as current draw is within spec.

One practical consideration, I will ASSume (guess) that the 12V supply is higher current than the 24 which is just feeding a phantom doubler.

It would be nice to use the center-tapped 12v full wave rectified.  You still get 24V peak swing, from top of +12 to bottom of -12V so a boost cap could be charged from +12V and step up to 12+24V or 36v with one cycle, 60+ with second step up.  Phantom is generally modest power draw so I would be inclined to optimize the higher current supply.

JR
 

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