Subject:
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Re: Temperature Sensor
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Newsgroups:
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lugnet.robotics
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Date:
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Wed, 28 Jul 1999 12:45:39 GMT
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Original-From:
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Jonathan Knudsen <JONATHAN@OREILLY.COMsaynotospam>
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Viewed:
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946 times
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Mike,
You are the man. Thanks for the information.
Digi-Key sells two thermistors that match
that description. The first is KC003T-ND, for
$2.71; it has 1 degree accuracy. The second
is KC003A-ND, for $11.50; it has +- .2 degree
accuracy.
I tried the first (which I happened to have), which
has the correct 10K @ 25C resistance and a
coefficient of -4.4%/C. In series with a 2.2K
resistor it still reads a few degrees high.
Jonathan
At 03:02 AM 7/28/99 GMT, you wrote:
> [...]
> The RCX wants a thermister with 12.2kohms at 25C with a -3.7%/C Temp Coef.
> This isn't equal to anything I can find. I think it is a 10kohm at 25C
> thermisiter with a either a trim pot or a fixed 2.2kohm resistor in series.
> A thermister with this resistor in series would need a -4.4%/C Temp Coef to
> fit the RCX and this is an available part. (Mouser 527-0503-10k) The Radio
> Shack thermister with a 2.2kohm resistor in series isn't too bad either.
> The RCX will read 25C at 25C and be off a little everywhere else since the
> Radio Shack has a lower Temp Coef of 3.7%/C to start with and the 2.2kohm
> only makes it worse. I've never tried the Mouser part but it looks like a
> good fit to me.
> Mike G.
--
Did you check the web site first?: http://www.crynwr.com/lego-robotics
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Message has 1 Reply:
 | | Re: Temperature Sensor
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| Jonathan Knudsen <lego-robotics@crynwr.com> wrote in message news:3.0.5.32.199907...net.com... (...) You might try a trim pot in place of the 2.2K and set the room temperature to be the correct value. You could later determine the trim pot value (...) (25 years ago, 28-Jul-99, to lugnet.robotics)
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Message is in Reply To:
| | Temperature Sensor
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| Does anyone know the exact characteristics of Lego's temperature sensor? It's easy enough to buy a thermistor and hook it up, but I'd like the temperature readings to be accurate. I've seen thermistors described by a resistance at 25 degrees C and a (...) (25 years ago, 26-Jul-99, to lugnet.robotics)
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