Thermistors

Definition

Thermistors are temperature-sensitive resistors that exhibit a change in resistance with temperature variations. They are widely used in various applications, including temperature sensing and control within embedded systems, due to their high sensitivity and quick response times. By integrating thermistors with microcontrollers, engineers can effectively monitor and manage thermal conditions in robotics and automation.

5 Must Know Facts For Your Next Test

1. Thermistors are highly sensitive to temperature changes, allowing them to detect small fluctuations effectively.
2. They can be used in both NTC and PTC configurations, making them versatile for different applications in embedded systems.
3. Thermistors typically have a nonlinear resistance-temperature relationship, which requires calibration for accurate temperature measurements.
4. When interfacing thermistors with embedded systems, it's crucial to use appropriate biasing circuits to ensure reliable readings.
5. Their fast response times make thermistors ideal for real-time temperature monitoring in robotics applications.

Review Questions

• How do thermistors function in embedded systems to monitor temperature changes?
  • Thermistors function by changing their resistance based on the surrounding temperature. In embedded systems, this change in resistance is measured using an analog-to-digital converter (ADC) to convert the analog voltage into a digital signal for the microcontroller. The microcontroller then processes this data to monitor and respond to temperature variations, enabling precise control in applications like robotics.
• Evaluate the advantages and disadvantages of using NTC versus PTC thermistors in temperature sensing applications.
  • NTC thermistors are more sensitive and provide better accuracy for measuring small changes in temperature, making them suitable for precise applications. However, they can become less stable at higher temperatures. On the other hand, PTC thermistors offer self-resetting capabilities and are useful for overcurrent protection but may not provide the same level of sensitivity for temperature measurement. Understanding these trade-offs is essential when selecting the appropriate thermistor type for specific applications.
• Design a simple circuit using a thermistor to monitor room temperature and discuss how it can be integrated into an automated control system.
  • To design a simple circuit using a thermistor, connect the thermistor in a voltage divider configuration with a fixed resistor. This setup allows changes in resistance from the thermistor due to temperature variations to produce corresponding voltage changes that can be read by an ADC. By programming a microcontroller to interpret this voltage data, the system can automate actions like turning on fans or heaters based on set temperature thresholds. This integration provides efficient thermal management within automated environments.

Related terms

NTC Thermistor: A type of thermistor whose resistance decreases as the temperature increases, commonly used for temperature measurement.

PTC Thermistor: A type of thermistor whose resistance increases with rising temperature, often utilized for overcurrent protection.

Analog-to-Digital Converter (ADC): A device that converts an analog signal, such as the voltage change from a thermistor, into a digital signal that can be processed by a microcontroller.