Nick, I've used the LM35's `Fahrenheit cousin' the LM34 for years with
wiring runs up to 300ft. The first thing I noticed is your output range;
667 - 733mv. If you were using an LM34 that would be 66.7 - 73.3 deg F.
Are you sure that's an LM35?

   The other thing, and this is very important, you need to install the
bypass cap, the R-C Damper, and the 2K resistor to isolate line/load
capacitance.

   I normally mount the bypass cap and R-C damper network right at the
sensor. At the other end on the input of the A/D, I use a 2K resistor,
followed by a 0.01uf cap.

   - Tom

At 09:40 PM 7/24/01 -0500, Nick Veys wrote:
>Greetings :)  I'm having trouble with some LM35 Centigrade temperature
>sensors... I'm simply trying to read them w/a multimeter and getting
>annoying values.  The Vss and Gnd are 5.12 and 0 respectively, and when
>I go to read the Vout, I get between .667 - .733 V.  Meaning my room is
>a toasty 66.7-73.3C.  Quite warm!  This is happening with 3 separate
>sensors!  Not sure what my problem is...  Any tips?  Perhaps I'm reading
>this totally wrong?
>
>nick@veys.com | www.veys.com/nick


------------------------------------------------------------------------
Tom Handley
New Age Communications
Since '75 before "New Age" and no one around here is waiting for UFOs ;-)

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