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My goal is to heat a thermistor as rapidly as possible.

The thermistor has a resistance value of 10k Ohms at 25 degrees C, and a negative temperature coefficient.

If I apply a constant voltage of 12V, the thermistor requires 30-50 seconds to heat up by 5-10 deg C above its starting temp. I would like the thermistor to reach 5-10 deg C above its start temp in less than 3 seconds, preferably within 1 second.

I am using a power source that can provide up to 30V, with a max draw of 3A.

I am considering using a constant-current source to try to achieve this goal, such as http://www.instructables.com/id/Constant-Current-Source-with-Operational-Amplifier/, but modified to provide greater current than the example project. Will this work toward my goal? Or are there better circuit options I could consider?

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    \$\begingroup\$ Have you calculated how much power is required to heat it in the required part and that your power supply is sufficient for this? \$\endgroup\$ – Eugene Sh. Jul 22 '15 at 14:34
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    \$\begingroup\$ If 12V produces a heat-up time of 30-50 seconds, how likely is it that 30V (the top limit of your supply and only 2.5x 12V) is really going to reduce that by a factor of 30? Even if your unspecified thermistor is capable of surviving the amount of power dissipation necessary? \$\endgroup\$ – brhans Jul 22 '15 at 14:36
  • \$\begingroup\$ Eugene, thanks -- I'll need to determine the mass to figure that out, so let me get back to you. Good suggestion. \$\endgroup\$ – ThermalModeler Jul 22 '15 at 14:39
  • \$\begingroup\$ brhans, the current draw when heating is only 0.4mA (thermistor is in voltage divider with 20k resistor), so if I could add more current I could increase the power to the thermistor. \$\endgroup\$ – ThermalModeler Jul 22 '15 at 14:41
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    \$\begingroup\$ Again, Why are you using a thermistor as a heater? That is a device used for measuring temperatures. Any old resistor could be a heater. \$\endgroup\$ – R Drast Jul 22 '15 at 15:14

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