Arduino Forum

Using Arduino => Sensors => Topic started by: Ownage on May 29, 2011, 06:19 pm

Title: Will the LM35 go up to 200 deg C?
Post by: Ownage on May 29, 2011, 06:19 pm
Hey,

This sensor seems popular with the arduino crowd, however I see that it is only rated to 155 deg C.  I need a sensor capable of reading around the range of 200 deg C with the reliability of +- a few degrees.  Do you think I can push the LM35 this high or it won't work?  Any suggestions on other sensors?

Thanks,
Ownage
Title: Re: Will the LM35 go up to 200 deg C?
Post by: RuggedCircuits on May 29, 2011, 07:34 pm
I don't think you can/should push it.

At higher temperatures an RTD is often used. Omega claims their RTD's are accurate to within ~2C at 200C:

http://www.omega.com/rtd.html

--
The Ruggeduino (http://ruggedcircuits.com/html/ruggeduino.html): compatible with Arduino UNO, 24V operation, all I/O's fused and protected
Title: Re: Will the LM35 go up to 200 deg C?
Post by: Ownage on May 30, 2011, 06:13 pm
Thanks.  They make you buy in packs of 100 though :(.  I didn't see any other cost effective RTDs.  Is there a cheaper way I can read this temp?
Title: Re: Will the LM35 go up to 200 deg C?
Post by: Ownage on May 30, 2011, 06:14 pm
Possibly automotive coolant temp sensors?  I live by a junkyard.
Title: Re: Will the LM35 go up to 200 deg C?
Post by: RuggedCircuits on May 30, 2011, 06:16 pm
How about one of these?

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=615-1045-ND

--
The Rugged Motor Driver (http://ruggedcircuits.com/html/rugged_motor_driver.html): two H-bridges, more power than an L298, fully protected
Title: Re: Will the LM35 go up to 200 deg C?
Post by: jluciani on May 31, 2011, 01:01 pm
A K or J type thermocouple will read these temperatures.
To interface these you will need a thermocouple interface
IC which is typically an SMD part.

I am working with the MAX31855 and K-type thermocouples.
I should have a sketch and schematic later this week.
I am using my PICOBEE board http://wiblocks.luciani.org/PICO/PICOBEE-index.html (http://wiblocks.luciani.org/PICO/PICOBEE-index.html)
to periodically measure temperature and transmit the timestamped data
to a PC.  The MAX31855 has a 14bit ADC and has a resolution
of 0.25degC. Not sure of the accuracy yet.

(* jcl *)
Title: Re: Will the LM35 go up to 200 deg C?
Post by: liuzengqiang on Jun 01, 2011, 03:41 am
Thermistors won't last 200 DegC and their housings aren't rated for that temperature. I would use thermocouple too. If you don't need sub DegC accuracy, you can find cheaper infrared remote temperature sensors too.
Title: Re: Will the LM35 go up to 200 deg C?
Post by: jluciani on Jun 10, 2011, 02:50 am
I just added a thermocouple + XBee application hint to my site -- http://wiblocks.luciani.org/docs/app-notes/picobee-tc.html (http://wiblocks.luciani.org/docs/app-notes/picobee-tc.html).

I interface a K-type thermocouple using the MAX31885KASA. I use the RTC on the PICOBEE
to periodically interrupt the uC. After an interrupt the temperature is read. The timestamped
data is transmitted using the XBEE.

(* jcl *)