Talk:Thermistor

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I think the thermistor tables and generator script should be changed as per http://www.brokentoaster.com/blog/?p=148

A few issues: DaveX 18:22, 6 November 2012 (UTC)

I agree that r1=0 seems nonsensical. Is there a better way to indicate we're only using one resistor (R2), and there is nothing there at the position marked "R1" on the schematic? Would tweaking the Python code so it prints "r1=None" or "r1=+INF" in that situation help? --DavidCary (talk) 07:20, 4 March 2014 (PST)

num_temps patch

The code at http://reprap.svn.sourceforge.net/viewvc/reprap/trunk/reprap/firmware/Arduino/utilities/createTemperatureLookup.py?view=markup&pathrev=3448 indicates a --num-temps=... option, but it is not in the code. The following patch adds it:

- createTemperatureLookupNophead.orig.py	2012-11-07 15:39:35.000000000 -0500
+++ createTemperatureLookupNophead.py	2012-11-07 15:38:03.000000000 -0500
@@ -66,7 +66,7 @@
     num_temps = int(20);
     
     try:
-        opts, args = getopt.getopt(argv, "h", ["help", "r0=", "t0=", "beta=", "r1=", "r2="])
+        opts, args = getopt.getopt(argv, "h", ["help", "r0=", "t0=", "beta=", "r1=", "r2=", "num-temps="])
     except getopt.GetoptError:
         usage()
         sys.exit(2)
@@ -85,6 +85,8 @@
             r1 = int(arg)
         elif opt == "--r2":
             r2 = int(arg)
+        elif opt == "--num-temps":
+            num_temps = int(arg)
 
     if r1:
         max_adc = int(1023 * r1 / (r1 + r2));
@@ -124,4 +126,4 @@
     print __doc__
 
 if __name__ == "__main__":
-    main(sys.argv[1:])
\ No newline at end of file
+    main(sys.argv[1:])


supplier part number

I'm thinking about deleting all the supplier part numbers from this page, keeping manufacturer part numbers.

Does anyone find the supplier part number useful? In any situation that I could possibly use the supplier part number, wouldn't the manufacturer part number work just as well? --DavidCary (talk) 07:20, 4 March 2014 (PST)

Does anyone ever use the Rz value?

This Thermistor page and the MeasuringThermistorBeta page devote a lot of space to "Rz", the resistance at 0 °C.

The firmware never uses Rz -- it has a lookup table of R vs T at many points (typically *not* including a point at 0 °C) and uses linear interpolation.

The Python script that generates that lookup table never uses Rz -- it calculates that lookup table from a command line something like

./createTemperatureLookup.py --r0=100000 --t0=25 --r1=0 --r2=4700 --beta=4066 --max-adc=1023

-- none of those input values are equal to Rz or derived from Rz, right?

Does anyone ever use the Rz value? --DavidCary (talk) 06:35, 7 March 2014 (PST)

Some folks outside of standard reprap might, like IceRap or http://www.3ders.org/articles/20120103-3d-ice-printer.html , and Rz could be on the specs of some thermistors. Pt-100 and Pt-1000 spec the Rz as part of their names. Also, Nophead's new script from http://hydraraptor.blogspot.com/2012/11/more-accurate-thermistor-tables.html and the Marlin script at https://github.com/ErikZalm/Marlin/blob/Marlin_v1/Marlin/createTemperatureLookupMarlin.py can both use the Rz if that is part of the range of interest. DaveX (talk) 06:57, 11 June 2014 (PDT)