If you want to go the thermocouple route and haven't
used them much before, don't worry about manual
calibration. An easier solution is to just get
something with cold junction compensation.

I did the whole ice-bath calibration thing for a
project a couple of years back, and was recently asked
to design a new thermocouple temperature sensor. The
customers weren't supposed to have to calibrate it so
we just got some K-type thermocouples from Omega and
the AD595 from Analog Devices:

http://www.analog.com/Analog_Root/productPage/productHome/0%2C2121%2CAD595%2C00.html

After using these I wouldn't want to do it manually
again. They're not overly cheap, but not _too_
expensive and a pretty good solution for one-offs. For
production I think you can do cold junction
compensation with just a transistor and a couple of
other parts.

Regards
T.C.


--- Picdude <picdude@NARWANI.ORG> wrote:
> Got a thermocouple probe here, but still need the
> "back end".  Even if I built
> a circuit for it, I'd still need to calibrate that.
> Chicken and egg story.
>
> Cheers,
> -Neil.
>
>
>
> On Saturday 19 July 2003 09:17, John Ferrell
> scribbled:
> > Don't overlook medical thermometers for the area
> around 100 degrees F.
> > Also, back in the dark ages we used thermocouple
> wire, a reference junction
> > in an ice water bath and read it with a balanced
> bridge (no current draw!)
> > I am inclined to believe that a good DVM and a
> piece of Chromel-Alumel or
> > Iron -constantan wire could be used for your
> purposes. I have no clue as to
> > where to find the wire today.
> >
> >
> > John Ferrell
> > 6241 Phillippi Rd
> > Julian NC 27283
> > Phone: (336)685-9606
> > johnferrell@earthlink.net
> > Dixie Competition Products
> > NSRCA 479 AMA 4190  W8CCW
> > "My Competition is Not My Enemy"
> >
> > ----- Original Message -----
> > From: "Picdude" <picdude@NARWANI.ORG>
> > To: <PICLIST@MITVMA.MIT.EDU>
> > Sent: Saturday, July 19, 2003 1:37 AM
> > Subject: [OT]: Measuring temperature...
> >
> >
> > Any of you folks have a way to measure temperature
> semi-accurately w/o
> > expensive thermometers?  Within a few degrees
> would be nice, and in the
> > range
> > of 0 to 300 deg F.  I'm trying to test the
> calibration of a temp sensor for
> > my car.
> >
> > I can use ice and hot water to get the 32- and
> 212-deg F points.  But is
> > there
> > a way to get 1 or 2 points between that, and a
> couple other points up to
> > about 300 deg F?  Is there any other liquid I
> could boil that has some
> > known boiling point perhaps?
> >
> > Cheers,
> > -Neil.
>
> --
> http://www.piclist.com#nomail Going offline? Don't
> AutoReply us!
> email listserv@mitvma.mit.edu with SET PICList
> DIGEST in the body


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