Brandon, I envy slightly you posted this message, not me.
I was always wondering, what is going on inside the computer
case with current flows, cause I'm forced to deal with cheap
uncertified Chinee's cases.
   One can literally hear this flows connecting Motherboard
Sound Input to spare black ground wire of power supply.
   I'm convinced, special advanced approach should be
taken, when investigating current & voltage distribution inside
the case. I'm not EE professional, nevertheless I suppose,
you should get a sort of MSP430FXXX 16-Bit Ultra-Low-Power
Microcontroller, from batteries powered.
   It should be well shielded. Case ground should not be
connected to microcontroller null. Microcontroller scheme
should be galvanicaly decoupled from output, as well as from
anything, but input.
   Differential input - two AD inputs with an advanced automatic
gain control capable of adjusting full scale to approx 0.1(?)v - 30v.
   And so on...

   Good luck.
   Mike.
----------------------

Brandon Stewart wrote:
> I am building a project that fits into an empty computer bay and is
powered
> from the computer's power supply. This is done off of a 12 volt line and
> through a 7805 -> which provides the 5V for the PIC to run on. Now, I plan
> to set up voltage dividers between the computer's 5 volt line and ground,
> and the 12 volt line and ground. This way I can use the A/D inputs of the
> PIC to monitor the computer's power supply voltage. This is done by
> choosing resistor values that provide monitoring voltages at 2.5 volts for
> each of the two lines being monitored. This is done to allow for the
> greatest fluctuation in the power supply voltage, whereby I can still
> monitor it without 'clipping'.
>
> ==> My question is, should I worry about sensing a voltage that is
> providing the power to my PIC to start with? Remember, I am monitoring a 5
> & a 12 volt line, and this 12 volt line is the same one that powers my PIC
> through a 7805.

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