How to Control Temperature with Electronic Devices

Temperature control is a critical operation in many applications, from industrial processes to home appliances. Depending on the specific requirements and the desired outcome (cooling or heating), several methods can be employed to achieve precise control of temperature. This guide will explore various techniques, including thermostatic switches, proportional temperature control, and the role of electronic devices in maintaining optimal temperatures.

Thermostatic Switches for Temperature Control

One common method of temperature control is through the use of thermostatic switches. These switches operate on a set-on and set-off principle, cutting off power to heaters at a higher temperature and turning them back on at a lower temperature. This approach can achieve a temperature range control of 2.5 to 5 degrees, depending on the components used and the system requirements. The devices used for sensing temperature include thermistors, RTD (Resistance Temperature Detectors) sensors, and thermocouples. These sensors are connected to the switching devices, allowing for precise control of heating and cooling processes.

The accuracy of control is influenced by thermal inertia, which means that the temperature may overshoot or undershoot the set point before stabilizing. This phenomenon is influenced by the responsiveness of the switching sensors. To mitigate this effect, some systems employ a method where a portion of the heaters is cut out once a preset temperature is reached, leaving fewer heater elements to maintain the remaining temperature difference. This approach can improve the accuracy of temperature control, but it may not achieve the precision needed in all applications.

Proportional Temperature Control

For applications requiring higher precision, proportional temperature control is often employed. This method uses a precise electronic circuit to gradually reduce the heating power as the actual temperature approaches the target temperature. By doing so, thermal inertia is reduced as the set temperature is approached, leading to very accurate temperature control—even down to a fraction of a degree. This technique is widely used in applications where temperature stability is crucial, such as in precision manufacturing and laboratory settings.

The Role of Electronic Devices in Temperature Control

Electronic devices themselves are not capable of significantly altering the temperature of a system. Instead, they serve as thermal sensors, sending signals to servo or automated circuits. These circuits then either cool or heat the system as necessary, ensuring that the desired temperature is maintained. For instance, in a home thermostat, the electronic device does not generate heat itself; rather, it sends a signal to the central heating or cooling system to adjust the temperature accordingly.

Practical Temperature Controllers

Industrial applications often require robust temperature control systems that can handle wide temperature ranges and provide real-time monitoring. Here's an example of a practical temperature control device:

Designed for controlling the temperature of various devices in industrial settings. Displays the temperature on a 1 LCD screen, with a range from -55°C to 125°C. The core of the circuit is a microcontroller from the 8051 family, which manages all functions. The IC DS1621 is used as the temperature sensor, providing 9-bit temperature readings. User-defined temperature settings are stored in a nonvolatile memory EEPROM via the 8051 microcontroller. Maximum and minimum temperature settings can be entered through a set of switches and stored in the EEPROM, allowing for a slight fluctuation within the desired range.

Proper temperature monitoring and protection of electronic components are essential to ensure the longevity and reliability of the system. If the temperature exceeds the specified range, it can cause damage to the circuit boards and other components. By utilizing temperature sensors to detect high temperatures, necessary actions can be taken to reduce the system temperature or shut down the system to avoid potential disasters.

By understanding and implementing these temperature control techniques, you can ensure that your electronic devices and systems operate efficiently and reliably, providing the precise temperature control needed for various applications.