Newsgroups: comp.robotics
Path: brunix!sgiblab!swrinde!cs.utexas.edu!mars.tsd.arlut.utexas.edu!andrew
From: andrew@tsd.arlut.utexas.edu (Andrew Wheeler)
Subject: Re: HELP: Simple A/D converter?
Message-ID: <1993Sep8.155957.22899@titan.tsd.arlut.utexas.edu>
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Organization: Applied Research Labs, University of Texas at Austin
References: <CD09zt.MK2@news2.cis.umn.edu>
Date: Wed, 8 Sep 1993 15:59:57 GMT
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horton@molbio.cbs.umn.edu (Robert Horton) writes:

>The temperatures I need to monitor are in the range of 25 to 100oC, and the
>measurement must be to within 0.5oC (more precise is probably better). I'd
>like to be able to record the temperature every half second or so. The main
>requirements beyond this are that the device be simple enough that your
>average biochemist can build it him/herself, and cheap enough that he/she
>would be willing to risk a few (?) dollars of precious Reagent Money
>(which is much more valuable than Equipment Money) on parts for a gizmo
>they have to make themselves.

>Any suggestions, hints, comments, clues, tips, or ideas would be most welcome.


Here's a few cheap alternatives:

1).  Pick up the 68HC11 EVBU.  I think it's around $80.  It has 8 8 bit A/D's that you could use, and you could
     download the info via RS232 to your host pc.  The hc11 is perfect for this sort of thing. . . .

2).  If $80 is too much, you could also just build the hc11 board yourself.  You could probably get away with
     just the HC11, a serial driver/receiver, and a ROM.  Look at the miniboard and also the powerglove
     interface available at apple.com or something like that. . . .

3).  In the above options, you're still stuck w/ building your analog circuitry (instrumentation amp, basically,
     which is no big deal).  If you don't want to mess with this then you could maybe get by with a soundblaster
     or Gravis UltraSound for around $100.  This would give you the line-inputs directly which might be useful.
     I personally would rather develop hc11 code over soundblaster code, but many people don't hold this opinion.

4).  If you'd ever want to do anything funky (ala digital signal processing), check out TI's c2x and c5x 
     evaluation board, which gives you one 14 bit A/D, D/A channel @ 44.1 khz, a fixed point dsp, and 
     a serial connection to your pc.  You can't beat this price with a stick, if you want a dsp. . . 

In all the systems above, development software is available for free, or with the purchase of the board in the 
case of the TI system.

-andrew

---
Andrew Wheeler
Applied Research Laboratories
University of Texas at Austin
andrew@titan.tsd.arlut.utexas.edu
512/835-3114
