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From: dmarten@nmsu.edu (MARTEN)
Newsgroups: sci.electronics
Subject: help with A/D converters, or +12V to -12V
Keywords: help, A/D, regulator, -12V
Message-ID: <1071@opus.NMSU.Edu>
Date: 18 Apr 91 18:47:49 GMT
Sender: news@NMSU.Edu
Lines: 25


Hello all,  I have a problem here that I have not been able to
solve, so I hope that somebody here
can answer it (or at least have a few ideas) for me...

Ok, here's what I am trying to do:  
     I am using an A/D chip that requires a  -12V reference voltage
to operate.  My problem is that I have only +5V and +12V to work
with (from a battery with a voltage regulator on it) and the -12V
must be referenced to the same ground as the +5V and +12V.
       So my question is, does anybody know of a way to get an A/D
converter to run on positive voltage, or do you know of  a way to
"invert" the 12V to make it negative?  
     I was thinking of somehow doubling the voltage and creating
a floating ground and reference from there, but I'm not sure that
would work.
     
Please Email me any ideas, comments, etc.
     Thanks a lot!
!================================!
  David Marten  
     New Mexico State University
 
     internet: dmarten@nmsu.edu
!================================!