You might want to look at the DS1624 digital thermometer and memory chip.

It has 13 bits of resolution and a temperature range of -25C to 125C, and
you
can store your calibration factors in the 256 bytes of eeprom.

It is also an I2C device, which may be a problem if you don't have good
noise
isolation.

Craig

-----Original Message-----
From: Mark Devin Newland <ape@ESKIMO.COM>
To: PICLIST@MITVMA.MIT.EDU <PICLIST@MITVMA.MIT.EDU>
Date: Saturday, April 25, 1998 11:19 AM
Subject: Re: Recomend temp sensor please


>
>For the simplest implementation, I agree.  Since you only need to go up to
240
>F (About 115 C) and most standard thermistors go up to 150 C (302 F) you
should
>be ok.  The problem will be on mounting it so the vibration doesn't shake
it to
>death.  A good thermal conducting silicon based product should help
vibration
>while still allowing the heat to get to the sensor.
>
>FIFTY CENTS?!?!?!  Where do you buy at? In quantities of 1, I can only find
>them for about $2.00 each.
>
>An alternative (and more costly / complicated / accurate?) way would be to
use
>thermocouples
>
>Bob Blick wrote:
>
>> Thermistors. Standard 10kohm@25C ones go for about $0.50 and can be read
>> any number of ways, depending on how accurate you want to get. Simplest
>> implementation would just use a capacitor(say 1uF) and a small
resistor(say
>> 220 ohms) off of any pic pin. Use the thermistor as a pullup to charge
the
>> cap. The pic pin hooks to the cap through the resistor. Drive the pic pin
>> low for a while, then TRIS it to an input and time how long it takes to
>> become "1".
>>
>> This method ignores most electrical demons, and can be done in the
>> background in a timer-based interrupt. And it's cheap.
>>
>> -bob
>>
>> At 09:10 AM 4/24/98 -0700, you wrote:
>> >Thank you for reading
>> >I need a recomendation for temp sensors. I want to attach sensors to
>> >automobile parts (carb, intake manifold, trans., differential...). Temps
>> >will not exceed 240 F. Also, how to avoid induction in wiring from high
>> >energy ignition.
>> >Thank you
>> >John
>> >
>>
>> http://www.bobblick.com/
>