Is there any way to determine if your Thermistors are 10k or 100k? I need to set the settings in my Marlin firmware. I tried one with the 100k setting, it worked, nothing blew up, but I still don't know if the readings were accurate.
\$\begingroup\$ That's true. Can that be done by someone with more rep? \$\endgroup\$– leeand00Jul 4, 2016 at 23:57
3\$\begingroup\$ Do you have a resistance measurement at a specific temperature? \$\endgroup\$– Ignacio Vazquez-AbramsJul 5, 2016 at 0:14
3\$\begingroup\$ Simply measure the resistance of the thermistor at room temperature. That resistance value will be very close to the actual value rating of the thermistor. \$\endgroup\$– Dwayne ReidJul 5, 2016 at 2:39
\$\begingroup\$ Since the question is now on EE stack exchange, but originated on a 3d printing exchange, can you explain what the thermistor is used for? The most common use in my experience is to monitor Lithium Ion battery cell temperature, but they have other uses, also, of course. \$\endgroup\$– user57037Jul 5, 2016 at 7:50
1\$\begingroup\$ Thermistors are used to read the temperature of the hotend and a so called heated bed. The former melts the plastic that is squirted out of a nozzle to lay it down in fused deposition modeling techniques (temperature between 180 and 240 for most common plastics PLA and ABS), the second is meant to keep the initial layers warm to enhance the print's adhesion on the print surface. \$\endgroup\$– kamuroJul 5, 2016 at 9:16
As @DwayneReid already said: take a multimeter and measure the resistivity. It will either be in the ballpark of 10KOhms or 100KOhms. If you already got a readout close to room temperature you're resistivity put in the firmware should be fine.
However, now it is still important to find out which make of thermistor you have, since they all behave slightly different. Find out about that in the manual of you 3D printer / hotend or in the documentation of wherever you got the thermistor from. Select the corresponding entry in Marlin then.