Wilteq WILTEQArduino Self-Study
Week 8 · Sensors & Task B

Session 37: Thermistors and calibration

Teach & build120 minLesson 24: Thermistors, the Beta Equation & Calibration

Learning outcomes

  • Convert a thermistor reading to Celsius with the Beta equation
  • Calibrate against a reference thermometer at three points
  • Decide between a fixed offset and correcting R0 or Beta
  • Drive a fan through a MOSFET with hysteresis

Kit and components

  • Uno, 10 kΩ NTC thermistor, 10 kΩ resistor, breadboard
  • Reference thermometer and sealed ice pack
  • MOSFET fan driver from S26

Pre-reading about 25 min

Students read these on their phones before class. They are listed on the student Before class page.

  1. Lesson 24: How an NTC thermistor works
  2. Lesson 24: Beta equation: resistance to temperature
  3. Lesson 24: Record the calibration

Session plan

  1. 0:0010 min
    Recap

    Quiz: dividers and hysteresis

  2. 0:1020 min
    Demo

    From ohms to degrees

    Work one Beta calculation on the board, then show the worked sketch giving the same result.

  3. 0:3045 min
    Measure

    Three-point calibration

    Students record ice-pack, room-air and hand-warmed readings against the reference thermometer and calculate the error at each point.

  4. 1:1535 min
    Build

    Thermostat fan

    Students add the lesson's fan hysteresis to the worked sketch and drive the S26 MOSFET fan.

  5. 1:5010 min
    Wrap-up

    Task B briefing

    Walk through the Task B brief and grid; plans are checked at the start of S38.

Checkpoint: ready to move on?

Each student has a three-point calibration table with errors, and a fan that switches on and off at two different temperatures.

Extension for fast finishers

Package the thermistor maths as the SimpleThermistor library from the extension lesson.

Catch-up path

Use two calibration points and a fixed offset.

Homework and practice

Complete the Task B plan.

Facilitator notes

  • No flames, soldering irons or heat guns near thermistors: hands, warm air and sealed ice packs only.
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