Temperature Sensor (thermocouple/RTD/IC)
Sensor
A device that measures temperature by converting heat into an electrical signal. Used in environmental monitoring, industrial processes, and consumer electronics.
What it looks like
Temperature Sensor (thermocouple/RTD/IC)
A typical sensor — exact shape, colour and markings vary between manufacturers.
Types & variants
Key specs
Temperature range
°CMin and max temperatures the sensor can measure accurately (e.g. -55°C to +125°C).
Accuracy
°C or %How close the measurement is to true temperature. Thermocouples: ±1-2°C, RTDs: ±0.1-0.5°C, ICs: ±0.5°C.
Response time
secondsHow quickly the sensor reacts to temperature changes. Thermocouples: fast, RTDs: slow, ICs: medium.
Output type
Voltage/Resistance/DigitalThermocouples: voltage (mV), RTDs: resistance (Ω), ICs: digital (I²C/SPI).
Sensitivity
µV/°C or Ω/°CHow much output changes per degree of temperature (e.g. 41µV/°C for Type K).
Markings
ICs: Part number (e.g. DS18B20). Thermocouples: Color codes (Type K: yellow, Type J: black). RTDs: Pt100/Pt1000 marking. Thermistors: R@25°C value (e.g. 10kΩ @25°C).
Standard values
Thermocouples: Standard types (K/J/T/E/N). RTDs: Pt100 (100Ω @0°C), Pt1000 (1000Ω @0°C). Thermistors: 10kΩ NTC (e.g. NTCLE100E3103JB0). ICs: 3.3V/5V compatible.
How to choose
1) Determine required temperature range. 2) Choose accuracy needed (±0.5°C for precision, ±2°C for general use). 3) Consider output type matching your system (analog/digital). 4) Evaluate response time needs. 5) Check operating voltage compatibility.
Pinout & package
ICs: 3-pin (VCC, GND, DATA) or 4-pin (VCC, GND, SDA, SCL). Thermocouples: 2 wires (signal, reference). RTDs: 2-4 wires (2-wire simple, 4-wire precise). Thermistors: 2 leads. Packages: TO-92, TO-220, SOT-23, probe-type.
Example circuits
- Microcontroller temperature monitoring (DS18B20 with Arduino)
- Industrial process control (RTD with Wheatstone bridge)
- Home thermostat (thermistor with comparator)
- 3D printer hotend (thermocouple with amplifier)
- HVAC system control (IC sensor with microcontroller)
Common failures
Drift in calibration over time, open/short circuits in wires, junction failure in thermocouples, cracked ceramic in RTDs. Symptoms: erratic readings, fixed temperature output, complete failure.
How to test
For ICs: Connect to microcontroller and read known temperature. For thermocouples: Measure mV output at known temperature (use reference junction). For RTDs/thermistors: Measure resistance at known temperature (use ice bath for 0°C).
Substitutes
Use same type with same range and accuracy. Thermocouples can be substituted with same type. RTDs can be replaced with Pt100 for Pt100. Thermistors can be replaced with similar R@25°C value. ICs can be substituted with pin-compatible alternatives.