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Old 2nd September 2012, 11:57 AM   #1
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Default Choosing the right transformer

Hi, I need some help here. I have a toroidal transformer tht has 200, 220, 260, 280 and 320 volt outputs. I need a 400-0-400 supply from here. How do I do this. Btw my primary is 230 volts. Can someone pls help me. Thanks
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Old 2nd September 2012, 01:13 PM   #2
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Originally Posted by jeffreyrow View Post
Hi, I need some help here. I have a toroidal transformer tht has 200, 220, 260, 280 and 320 volt outputs. I need a 400-0-400 supply from here. How do I do this. Btw my primary is 230 volts. Can someone pls help me. Thanks
Hi

I assume the schematic you have shows a 400-0-400 transformer. In that case, you don't have to follow it blindly, just use a solid state bridge and the 280 volt winding.
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Old 2nd September 2012, 01:36 PM   #3
kevinkr is offline kevinkr  United States
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I split this off from another thread as this question was OT there. Please start a new thread rather than diverting the direction of another one. Thanks...
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Old 2nd September 2012, 05:40 PM   #4
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for a 400-0-400 v supply, you are basically looking at 0-800, the most your traansformer can supply is 0-320. Im assuming you dont need a dual rail supply at +/-500v so you can use the 200 or 220 volt output and use a voltage doubling rectifier instead of a full wave/bridge rectifier.
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Old 2nd September 2012, 05:52 PM   #5
AndrewT is online now AndrewT  Scotland
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Values/tubes on a dual polarity supply !
We usually only see a small -ve supply to bias the stages.
The values all behave as Nchannel only, there are no complements.
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Old 2nd September 2012, 06:07 PM   #6
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Quote:
Originally Posted by jeffreyrow View Post
Hi, I need some help here. I have a toroidal transformer tht has 200, 220, 260, 280 and 320 volt outputs. I need a 400-0-400 supply from here. How do I do this. Btw my primary is 230 volts. Can someone pls help me. Thanks
Jeffrey: Do you just need a +400VDC B+? ie, no -400VDC? Is this for a tube amp?
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Old 2nd September 2012, 06:27 PM   #7
tinitus is offline tinitus  Europe
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is this for a tube amp ? boy, are trying to be funny ?

but there are indeed quite many tube amp power supply trafos built/sold with symmetric voltages, and CT point
not that I know why exactly either
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Old 2nd September 2012, 06:49 PM   #8
AndrewT is online now AndrewT  Scotland
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Centre tapped output transformer.
But both ends are connected to B+, not to B- & B+
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Old 2nd September 2012, 07:34 PM   #9
Pano is offline Pano  United States
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Right. What do you need for B+?
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Old 2nd September 2012, 07:51 PM   #10
kevinkr is offline kevinkr  United States
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I'm wondering if he was in fact looking for 800VCT AKA 400-0-400 in which case this transformer will not get him there, if OTOH he is looking for something close to the sort of output one could expect from 800VCT with a tube rectifier then the 320V tap with a solid state bridge rectifier might get him reasonably close. (or not)
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