use a Computer SMPS to create a dual polarity DC supply ?

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AndrewT

New member
Hi all, I'm new here but experienced in analogue electronics and all the safety issues of DIY electronics.

I have a few working but redundant Computer SMPS and would like to experiment with using SMPS as the DC supplies to amplifiers.

Is it feasible to convert an SMPS to give a dual polarity DC supply? i.e. mains AC to +-Vdc?
How do I determine the feedback route and components that control the output voltage?
If the SMPS is rated @ 500W, does that mean that it can supply a continuous 500VA at an appropriate DC voltage? or should it be de-rated for continuous duty?
 
A

AndrewT

New member
If the SMPS is rated @ 500W, does that mean that it can supply a continuous 500VA at an appropriate DC voltage?
Click to expand...
or does 500W SMPS mean a maximum of 500W, but at a lower duty cycle for average power delivery?
 
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PetruV

New member
Its pretty easy to modify these,you only have to modify the resistor values before the optocoupler and replace components on the output side to ones which can withstand the voltage that you try to get out. you can go a limited amount before you hit 100% duty cycle and have to add windings to your transformer,im nowhere near an expert,but i know this is true information,and tried to apply it
 
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KX36

New member
Each rail in an ATX supply has its own power limit, i.e. you can't pull 500W out of a single rail in a 500W ATX supply.
The modification PetruV suggests may allow you to change the output voltage of a rail (up to a point) but not its polarity, the high current rails of an ATX supply are all positive referenced to a common ground. To get a negative rail at high power would probably require some heavy modification of the secondary side and the main switching transformer.
 
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