On Wed, 2002-01-16 at 09:12, Rick Mann wrote:
> My application requires a remote temperature sensor, accurate to a degree F
> or better. I need to be able to place a temp probe 2 to 3 meters away from
> the controller.
>
> I was thinking of using an LM34DZ with a three-wire cable (and sealing up
> the sensor in some heat shrink), then I saw a post about the LM335, (which
> reads degrees K), and I decided that made more sense (it avoids the need for
> a negative Vref).
>
> However, the LM335 is a two-terminal device (plus the adjust), and requires
> a current source. The app note shows a generalized current source (can I
> just use a resistor?). And the trimmer pot looks like it should be near the
> sensor; is that necessary? Or can it be on the board?
>
> If anyone has any other suggestions for a variable-voltage-output sensor to
> operate in the room temperature range, I'd appreciate it. Thanks!
>

I'm NOT an electrical engineer, but I had the same problem and used a
Dallas 1 wire (which is, of course, more than 1 wire) device.  DS18S20
or 21 if memory serves.  I think these are 0.5C accurate.  No analogue
cruft, no problems with changing probe wires, no calibration :-)

My $0.02
/Kevin
--
Kevin J. Maciunas              Net: kevin@cs.adelaide.edu.au
Dept. of Computer Science      Ph : +61 8 8303 5845
University of Adelaide         Fax: +61 8 8303 4366
Adelaide 5005 SOUTH AUSTRALIA  Web: http://www.cs.adelaide.edu.au/~kevin
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