In this DIY electronics project, we will design and build a Precision Temperature Controller using the SSC3S211-TL. The SSC3S211-TL is a highly capable, linear-output temperature sensor that can be used for a wide range of temperature sensing applications. It offers high accuracy, low power consumption, and is particularly useful in environments where precise temperature regulation is required.
Our goal is to create a simple temperature controller for controlling the temperature of a small heating element (such as a Peltier device or resistive heater). This project can be applied to various uses like incubators, temperature-controlled enclosures, or even small-scale climate control systems for electronics or plants. By the end of this project, you will have a fully functional temperature controller that can be adjusted based on a setpoint temperature, with precise regulation using the SSC3S211-TL sensor.
Understanding the SSC3S211-TL
Before diving into the project, it is important to understand the role the SSC3S211-TL plays in the circuit. This component is a silicon temperature sensor designed to output an analog voltage proportional to the temperature. The key features of the SSC3S211-TL include:
● Linear Output: The output voltage increases linearly with temperature, making it easy to interface with analog control systems.
● High Accuracy: The SSC3S211-TL provides a high level of temperature accuracy, making it ideal for applications where precise control is essential.
● Low Power Consumption: This makes it suitable for battery-powered projects or low-power systems.
● Wide Temperature Range: The SSC3S211-TL has an operating range that spans from -40°C to +125°C, which is ideal for general temperature control applications.
The sensor provides a voltage output that corresponds to temperature, which can be measured and used to compare with a setpoint. The project will then use this temperature reading to control a heating element, ensuring the temperature stays within a desired range.
Materials and Components Needed
Here are the materials and components we will need for this DIY project:
● SSC3S211-TL Temperature Sensor
● Operational Amplifier (e.g., LM358 or similar)
● N-channel MOSFET (e.g., IRF540N)
● Resistors and Capacitors (for setting the reference voltage and smoothing the output)
● Peltier or resistive heater
● Microcontroller or Potentiometer (for adjusting the setpoint temperature)
● 12V Power Supply
● Heat sink (for the MOSFET or heating element)
● LED (optional, for visual indication of heating)
● Relay or Solid State Relay (for switching the heating element)
● Breadboard or PCB for assembling the circuit
● Wires and connectors
● Soldering iron and solder
Step 1: Circuit Design
Let’s first discuss the design of the temperature controller circuit. The SSC3S211-TL sensor provides an analog voltage output that varies with temperature. Our goal is to measure this voltage and use it to control a heater based on a temperature setpoint.
SSC3S211-TL Sensor Connections: The sensor has three pins: Vcc, GND, and Output. The Vcc pin will be connected to a 5V or 3.3V supply, depending on the system voltage. The GND pin will be connected to the ground of the system. The output pin will provide the analog voltage corresponding to the temperature.
Operational Amplifier: The operational amplifier (Op-Amp) will be used to compare the temperature reading (from the SSC3S211-TL sensor) with the setpoint. The Op-Amp will be configured as a comparator. The non-inverting input of the Op-Amp will receive the output voltage of the SSC3S211-TL sensor, while the inverting input will be connected to a setpoint voltage. This voltage will be generated using a potentiometer. By adjusting the potentiometer, you can set the desired temperature.
MOSFET for Heating Control: The output of the Op-Amp will be used to control a MOSFET. When the temperature exceeds the setpoint, the Op-Amp will output a high voltage, turning on the MOSFET and powering the heating element. If the temperature is below the setpoint, the Op-Amp will output a low voltage, turning off the MOSFET.
Heater (Peltier/Resistive): The MOSFET will switch the current to the heating element, allowing it to either heat up or cool down the system. A heat sink may be needed to dissipate heat from the heating element or the MOSFET if the current drawn is significant.
Feedback and Calibration: The SSC3S211-TL sensor will be connected in such a way that its output voltage will be compared with the setpoint voltage from the potentiometer. Depending on whether the temperature is above or below the setpoint, the Op-Amp will control the MOSFET to adjust the heating element accordingly.
Optional LED Indicator: A simple LED can be added to indicate when the heating element is on. The LED will be connected in parallel with the MOSFET, lighting up when the MOSFET is conducting.
Step 2: Assembling the Circuit
Now that we have the design in place, we can begin assembling the components on a breadboard or PCB.
- Connect the SSC3S211-TL Sensor:
● Connect the Vcc pin of the SSC3S211-TL to the 5V supply (or the appropriate supply voltage as per your design).
● Connect the GND pin to the ground of the system.
● Connect the output pin of the SSC3S211-TL to the non-inverting input (+) of the Op-Amp.
- Setting the Setpoint:
● Connect a potentiometer to the inverting input (-) of the Op-Amp. One side of the potentiometer will go to ground, and the other side will be connected to the 5V supply. The wiper (middle pin) will provide the adjustable reference voltage that will determine the setpoint temperature.
- Operational Amplifier (Op-Amp):
● Connect the Op-Amp’s positive power pin to 5V and its ground pin to ground.
● The output of the Op-Amp will be connected to the gate of the MOSFET.
● The Op-Amp’s output will be high when the temperature is above the setpoint, turning the MOSFET on, and low when the temperature is below the setpoint, turning the MOSFET off.
- MOSFET and Heater:
● The MOSFET will act as the switch for the heating element. Connect the drain of the MOSFET to the negative terminal of the heating element, and the source to ground.
● The positive terminal of the heating element will be connected to the 12V supply.
- LED Indicator (Optional):
● Connect a current-limiting resistor to the gate of the MOSFET and the anode of the LED. The cathode of the LED will be connected to ground.
- Capacitors and Resistors:
● Use capacitors to filter out noise in the power supply and the Op-Amp’s output to stabilize the system.
● Place a pull-down resistor (e.g., 10kΩ) between the output of the Op-Amp and ground to ensure the MOSFET turns off when the Op-Amp is in a low state.
Step 3: Testing the Circuit
Once the circuit is assembled, you can proceed to test it.
- Powering the Circuit:
● Connect the 5V power supply to the circuit and ensure that all components are properly powered. The SSC3S211-TL will begin providing a temperature-dependent voltage.
- Adjusting the Setpoint:
● Turn the potentiometer to set the desired temperature. The voltage from the potentiometer will be compared with the voltage from the SSC3S211-TL to determine whether the temperature is higher or lower than the setpoint.
- Monitoring the Temperature:
● Use a thermometer to monitor the actual temperature of the system. As the temperature increases and crosses the setpoint, the MOSFET should turn on, powering the heating element. The heating element should continue running until the temperature reaches the desired value.
- Fine-Tuning:
● Adjust the potentiometer to change the setpoint and ensure that the system turns the heater on and off correctly in response to temperature changes.
Step 4: Refining the Design
Once the basic system is working, you can refine and enhance the design in the following ways:
Adding Cooling Control: If you are controlling both heating and cooling (e.g., using a Peltier device), you can add another MOSFET or relay to control the cooling side.
PID Control: For smoother temperature regulation, you could implement a PID (Proportional-Integral-Derivative) control loop for more precise temperature control, though this would require a more complex setup with a microcontroller.
Temperature Calibration: You can calibrate the SSC3S211-TL sensor by comparing it with a known temperature sensor and adjusting the reference voltage or adding compensation circuitry.
Conclusion
In this project, we’ve successfully designed and built a Precision Temperature Controller using the SSC3S211-TL temperature sensor. This simple yet effective circuit offers precise temperature control for applications such as temperature-sensitive experiments, small heating systems, or even incubators. The project can be easily expanded with additional features like cooling control or digital interfaces, and is a solid foundation for more complex temperature regulation systems.
By using the SSC3S211-TL sensor, we’ve created a highly accurate, low-power temperature sensing solution that is well-suited for a variety of DIY temperature control applications.