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at power supply contruction

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truenoteno

New Member
i have made a basic power supply from 2 12v car batteries (to get +12,G-12), i have all the votlages correct, i plug it in and nothing happens, is there some sort of timing for the voltages ?
 

NaN

New Member
Ironically i was just fiddling with one of my old AT power supplies.

To get proper +/- 12V, you often need to adequately load the 5V supply. To my surprise however, this loading is to about 5% of the rated supply power.

For me, i had a 200W power supply, and at 5V i had to load it to about 10W. Do the math and you see i need a 10W, 2.5 Ohm resistor! (( I didnt happen to have one lying around )).

With some make-shift temporary testing resistances, I was drawing nearly 2A though the 5V line before i got it up to 12V regulation!

Hope it helps...
:NaN:
 

truenoteno

New Member
did you make your own power supply for your comp ? or were you just loading it.

where would you put the load resistor ?
 

stevez

Active Member
If what you did is attempt to wire two 12 v car batteries together they should be in series - with the + terminal of one connected to the - terminal of the other. The point where those connect will be neutral or ground, the free + will be +12 v and the free - will be -12 v. You should also see 24 to 26 volts across the free + and -.
 
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