Printable catalog (PDF)
NEW PRODUCT – 10K 1% Epoxy Thermistor [3950 NTC]. Need to measure something damp? This epoxy-coated 10K thermistor is an inexpensive way to measure temperature in weather or liquids. The resistance in 25 °C is 10K (+- 1%). The resistance goes down as it gets warmer and goes up as it gets cooler. For specific temperature-to-resistance, check the lookup table.
These are often used for air conditioners, water lines, and other places where they can get damp. The PVC coating of the wires is good up to 105 °C so this isn’t good for very hot stuff.
We even toss in an additional 1% 10K resistor which you can use as calibration or for a resistor divider.
FEED
Where did you guys purchase these? Curious if a similar product reaches past 105C. Need to measure the temperature of water and steam for a “smart” tea kettle!
Comment by Alexander Mills — May 24, 2011 @ 6:28 pm
Never mind, got it.
http://search.digikey.com/scripts/DkSearch/dksus.dll
Comment by Alexander Mills — May 24, 2011 @ 6:37 pm
Would this work for the chumby hacker board LiPo sense line?
Comment by tz — May 24, 2011 @ 7:57 pm
mills, anything with pvc-covered wire will have a 105 degree max usage. Its a property of PVC not of the thermistor
we are working on getting a teflon-wired temp sensor so you can measure up to 250 degC
tz, good question. depends on what the processor’s looking for in terms of the resistance levels. you’d have to compare what the cutoff resistances are to the table (there is no ‘standard’ thermistor)
Comment by ladyada — May 24, 2011 @ 10:37 pm
hey email me if anyone needs a function fit (a mathematical function) for the look up table!
pinopoom [at] gmail.com
Comment by rei — May 24, 2011 @ 11:14 pm
rei, that would be cool, please post it here. would save us some matlabbin
Comment by ladyada — May 25, 2011 @ 4:43 pm
From wikipedia I pulled this equation:
T=B/ln(R/rinf)
where rinf=R0 e^(-B/T0)
This thermistor has a B value of 3950, R0=10^4 and T0=298.15
Comment by Abe — May 26, 2011 @ 2:00 pm