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Variable Voltage Regulators with + and - 12v input? Answered

Hi,

I have put one of these together for an ATX power supply and have come across something that I might be getting wrong....

In mocking up the LM317 circuit in breadboard (standar one found everywhere on line and on the LM317 pages), I have got the thing metering -11v to +11v??? I am using one of the black ground wires of the PSU on the black side of the volt meter, but cant figure out why I am not just getting positive voltages??? Could the diode be faulty? Or is this in fact correct?

Any help appreciated...

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steveastroukBest Answer (author)2012-03-04

Depends where you took "ground" for the regulator from. If you've taken it from -12V, that will do what you say.

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