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 Robotics / 5854
5853  |  5855
Subject: 
Re: Temperature Sensor
Newsgroups: 
lugnet.robotics
Date: 
Wed, 28 Jul 1999 03:02:29 GMT
Viewed: 
838 times
  
Jonathan Knudsen <lego-robotics@crynwr.com> wrote in message
news:3.0.5.32.19990726121606.00907770@m9.sprynet.com...
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.

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.



Message has 1 Reply:
  Re: Temperature Sensor
 
(...) At one time Radio Shack sold 10K thermistors but I have not checked lately. Don't remember their temperature coefficient. I do not know the Mouser source. Pardon me if this is an(*) FAQ but could you let me/us know how to contact Mouser? (...) (25 years ago, 28-Jul-99, to lugnet.robotics)

Message is in Reply To:
  Temperature Sensor
 
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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