I have an ic with a poorly performing thermistor I'd like to replace with a more accurate, more sensitive component. The first step is finding out what thermistor I likely have or at least who made it. If it wasn't garbage, it ought to perform with very high accuracy in the temperature range 80°F - 110°F (+- .5° or better) and with reasonable accuracy from 60°F - 125°F (+- 2° or better). I am aware that the accuracy is really a matter of the chip interpreting the resistance value from the thermistor... but something has to be wrong with this particular thermistor since I have two, and only this one is about 10 degrees off.

It is a bright blue, dipped component on two copper leads about 3.5 cm long. The product it's in is a chicken egg incubator currently made by Georgia, US poultry equipment company GQF. Unfortunately, they appear to have decided to do things on the cheap. (The cheep?) Although touted as a high tech, reliable option this particular electronic incubator takes wildly inaccurate temperature readings. I have another which reads temperature accurately enough to hatch chicks... Photos attached.close up (no identifying markings, deep sky blue plastic dip, bright copper leads, "U" shapedas installed

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    \$\begingroup\$ You should take the 'good' thermistor and characterize its resistance over the expected operating temperature. That would give a good starting point for finding an equivalent replacement. \$\endgroup\$ – brhans Apr 19 at 17:00
  • \$\begingroup\$ That would be a start, although the good one is a couple of degrees off itself. The only way I've been able to get good results from either is by dangling an aquarium thermometer into the depths and adjusting the incubator "set temperature" according to the readout I am getting on the thermometer... \$\endgroup\$ – krnntp Apr 19 at 17:16
  • \$\begingroup\$ I have thought of correlating the resistance values with what the incubator display shows (it has a °F digital readout). That will be the route I go if no one recognizes this component \$\endgroup\$ – krnntp Apr 19 at 17:19
  • \$\begingroup\$ Once you know the range of resistances the thermistor presents you could solder in a selection of fixed resistors (with 1% or better tolerance) and log the reading on the display for each resistor. \$\endgroup\$ – brhans Apr 19 at 17:20
  • \$\begingroup\$ ...or a precision trimpot; tweak, remove, measure, repeat. Load the temp and resistances into excel, plot a scatter chart. Use that as a guide for finding a replacement. With no markings, the exact manufacturer and model will be neigh impossible to discern. \$\endgroup\$ – rdtsc Apr 19 at 17:53

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