From: "Adam Yudelman"
Subject: Re: Temperature sensor at 400F?
X-Newsreader: Microsoft Outlook Express 4.72.3110.5
Date: Thu, 31 Oct 2002 20:31:33 GMT
NNTP-Posting-Date: Thu, 31 Oct 2002 15:31:33 EST
What might the thermal time constant of a smallish tungsten bulb be? My
first thought was on the order of a minute, but it IS a vacuum in there, so
maybe much less? I suppose it would also depend on where and how the bulb
came into contact with the heat source.
Are there any heat-conductive grease type products that work at this
temperature? This might help me in more than one way.
I think this probably isn't the best way for me to go, as I would prefer to
use parts that are better spec'd and require less calibration, but it might
be an interesting experiment to see if I could build a lightbulb setup that
performed as well as a thermocouple one.
And thanks to everyone else for the suggestions, I think I have found what I
need on the omega site..
Tom Bruhns wrote in message
>An extremely cheap alternative: a tungsten RTD. That is, a small
>light bulb with wire leads. Although you have to calibrate for the
>resistance at one temperature and find an accurate formula or table
>for the temperature coefficient (or measure at a few points), there
>are some advantages: very cheap, sealed, available locally almost
>anywhere, available over a moderate range of nominal resistance
>values. Your temp is just a bit high to be using a base that's
>soldered on, but for lower temps, that gives an even broader range of
>For more demanding applications, I'd go with the platinum RTD or
>thermocouple, but thought it worth mentioning that it CAN be done
>"Adam Yudelman" wrote in message
>> I need a temperature sensor that can withstand temperatures up to about
>> (210C) and have an absolute accuracy of +-5F (+-3C) in the upper
>> range (slightly looser tolerances may be acceptable).
>> I have browsed through some catalogues I have on hand, but can't find any
>> parts spec'd higher than 125C. I know temp-controlled soldering stations
>> will have such a sensor in them, but I have doubts about the accuracy of
>> such a sensor (might it work?).
>> Can anyone reccommend anything? I only need a few of these (<10) to build
>> prototype. If you know of anything close, please let me know, as I may be
>> able to change the requirements at a later time.