W1209 Temperature Controller

The W1209 Temperature Controller is one of the most popular and affordable thermostat modules used in automation and temperature-dependent electronics. With an impressive operating range of –50°C to +110°C, this module is designed to control heating or cooling equipment based on the temperature values you set.

Featuring a high-accuracy NTC thermistor probe, a powerful 250V/20A relay, and a bright digital 7-segment display, the W1209 offers both precision and ease of use. Whether you’re building a DIY incubator, controlling aquarium water temperature, regulating PC cooling fans, or automating smart home temperature systems, this module is a highly reliable and versatile solution.

It integrates smoothly with Arduino, Raspberry Pi (using relay control), and NodeMCU IoT setups for smart automation projects.

Key Technical Specifications

• Operating Voltage: 12V DC

• Temperature Range: –50°C to +110°C

• Sensor Type: 10K NTC Waterproof Probe

• Relay Output: Up to 20A @ 14V DC / 10A @ 250V AC

• Display: 3-Digit LED 7-Segment

• Control Mode: Heating / Cooling

• Accuracy: ±0.1°C

• Size: 48mm × 40mm

• Buttons: SET / + / –

• Protection: Temperature calibration, delay start, hysteresis settings

Advanced Features

1. Heating & Cooling Dual Mode

Select between HEAT mode for incubators, heaters, and warmers, or COOL mode for refrigerators, cooling fans, and chillers.

2. Programmable Settings

• Temperature Setpoint

• Hysteresis (difference between ON/OFF switching)

• High/Low temperature limits

• Delay protection

• Sensor calibration (C/F)

3. High-Power Relay Control

Capable of switching high-power AC and DC loads like motors, pumps, lamps, and heaters.

4. Waterproof Temperature Probe

Ideal for aquariums, water tanks, and humid environments.

5. Arduino & IoT Friendly

Can be integrated with:

• Arduino boards

• NodeMCU (WiFi automation)

• Raspberry Pi relay control setups

Applications

• DIY Egg Incubators

• Aquarium & Fish Tank Temperature Control

• Reptile & Pet Terrariums

• Water Heater / Boiling Control

• Cooling Fans & PC Case Temperature Control

• Greenhouse Climate Control

• Smart Home Automation Projects

• Solar Power Temperature Safety Monitoring

• Industrial Temperature Monitoring

Find more components from:

• Electronics Components

• Arduino and Accessories

• Tools and Accessories

• ICs

Precautions

• Use 12V DC regulated power for stable operation.

• Do not exceed the relay’s maximum load.

• Keep the sensor away from heating coils to avoid damage.

• Ensure proper electrical insulation to prevent short circuits.

• Calibrate the sensor before use for high-precision applications.

• Not suitable for extremely humid environments without a waterproof enclosure.

YouTube Tutorial – How to Use W1209

Watch Video

4. Product Summary

The W1209 Digital Temperature Controller is a versatile, affordable, and feature-rich thermostat module used for heating and cooling automation. With its wide temperature range, high-power relay, programmable settings, and waterproof sensor, it is ideal for DIY incubators, aquariums, terrariums, IoT devices, and smart automation applications.