At 01:40 PM 8/14/02 -0700, you wrote:

>Couldn't a little careful calibration fix that?

Not if it shifts with the breeze, which is the issue. Under lab
conditions, sure, but usually you'd prefer to have the sensors
interchangeable so when one gets wrecked it can be replaced
quickly. And you do not want the reading to change when the
door opens or when someone touches or gets near to something.

>Well, anyways, what do you think of the LM35 solution that someone else
>offered?

It's not bad at all, IMHO, in this temperature range.
Pretty good accuracy (about the best I've
seen in a cheap semiconductor sensor), and inexpensive.

I'm not sure exactly what method they use for the actual
temperature measurement, and when I asked Pease about it,
he clammed up tight, there are obviously some proprietary
aspects to it, but it seems to be in capable hands anyway.

And doesn't have the somewhat dubious history that the 18S20's
predecessor had with moisture ingress issues causing the reading
to drift.

The "one-wire" bus also has its issues. It works great for short
distances and is quite easy to use, but is suspect for long runs.

>It would require the TIG welded tube that I was saying would be
>expensive, but other than that, I think I remember it being a relatively
>good sensor, and with a thermal epoxy bond to the stainless steel tube, it
>should measure temperature fairly well, I think.

I'd try to avoid the epoxy in favor of something with more "give", but sure.
At an immersion over 10* the tube diameter you don't have to worry about
accuracy so much as slow response (which isn't an issue here).

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
9/11 United we Stand

--
http://www.piclist.com hint: To leave the PICList
mailto:piclist-unsubscribe-request@mitvma.mit.edu