The W1209 Digital Temperature Controller Module is a compact and inexpensive thermostat control board widely used for temperature regulation in DIY projects and appliances. It features a temperature sensor, a relay, and a digital display.
 
 Key Features
Operating Voltage: DC 12V
Temperature Range: -50°C to +110°C
Control Accuracy: ±0.1°C
Relay Output: 1 Channel, 10A @ 250VAC / 20A @ 14VDC
Sensor Type: NTC Thermistor (10K)
Display: 3-digit 7-segment LED
Buttons: 3 (SET, +, -)
Size: ~48mm x 40mm
Working Modes: Heating or Cooling
Parameter Memory: Retains settings after power loss
 
Pin Configuration
 
Pin
Description
DC+
+12V Power Supply
DC-
Ground
K0
Relay Normally Open Contact
K1
Relay Common Contact
 
Sensor Connector: 2-pin for NTC temperature probe.
 
Working Principle
The NTC sensor detects the current temperature.
User sets:
Set Temperature (P0)
Hysteresis (P1)
Upper & Lower Limits (P2, P3)
Temperature Calibration (P4)
Delay Start (P5)
Heating or Cooling Mode (P6)
If the temperature crosses the set threshold, the relay activates/deactivates:
Heating Mode: Relay ON when temp < setpoint
Cooling Mode: Relay ON when temp > setpoint
 
Parameter Settings
P0 → Heating (H) / Cooling (C)
P1 → Hysteresis (default 2°C)
P2 → Upper Limit (110°C)
P3 → Lower Limit (-50°C)
P4 → Temperature Calibration (±10°C)
P5 → Delay Start (0–10 minutes)
P6 → High Temp Alarm (OFF/ON)
 
Applications
✔ Incubator or aquarium heating
✔ Refrigerator or cooling fan control
✔ Greenhouse temperature management
✔ IoT-based temperature automation (with relay integration)
 
Connection Example
Power: Connect 12V DC to DC+ and DC-
Relay Output: Connect load (heater/cooler) through K0 & K1
Sensor: Plug NTC probe into the 2-pin connector
 
Package includes: 1xW1209 Digital Temperature Controller Module