I have a used piece of equipment (basically a specialized laminator) that uses a thermistor to measure the temperature in operation. When I got it, I found that it was heating, but the system never saw the temperature rise.
Upon taking it apart, I found the thermistor (a tiny 4mm diameter x 2mm high metal disc with no obvious markings) completely detached from the tiny wires that used to keep it in circuit.
In order to find a replacement, I used some normal resistors to see what result I got on the temperature readout on the machine. These are regular cheap (+/- 10% tolerance) resistors.
From this data, how can I select a replacement? I see lots and lots of NTC thermistors on Digi-Key, but I'm not sure how to derive the values like B25/85 to select one.
The data I gathered is as follows:
R (Ω) | T (°C) --------------- 10k | 25 5.6k | 42 3.3k | 57 1.5k | 84 820 | 107 470 | 129 330 | 146 220 | 167 150 | 186
The laminator's setting ranges from 100°C to 180°C. It doesn't need to be SUPER accurate, but within 5°C +/- would be preferable.
I know this is a specific question, but I can't really find any documentation on how to derive these values. I found a thermistor calculator and was able to get the various coefficients, but I don't know how to select from a supplier based on that.