Adafruit
Adafruit PT100 RTD Temperature Sensor Amplifier - MAX31865
The Adafruit PT100 RTD Temperature Sensor Amplifier is a breakout board for the MAX31865 precision RTD-to-digital converter. It reads 2-, 3-, or 4-wire PT100...
The Adafruit PT100 RTD Temperature Sensor Amplifier is a breakout board for the MAX31865 precision RTD-to-digital converter. It reads 2-, 3-, or 4-wire PT100 platinum resistance temperature detectors over SPI, delivering laboratory-grade temperature accuracy and repeatability that surpasses thermocouples.
PT100 RTDs use a platinum resistor element (100Ω at 0°C) whose resistance changes predictably with temperature. The MAX31865 handles signal amplification, wire compensation, and analogue-to-digital conversion — you simply read the resistance ratio over SPI and convert to temperature. The board includes a 430Ω 0.1% precision reference resistor and is 5V-safe with an on-board 3.3V regulator and level shifting.
Key Features
- MAX31865 RTD Amplifier – Precision ADC with automatic wire resistance compensation
- 2-, 3-, or 4-Wire RTD Support – Compatible with any PT100 (100Ω at 0°C) sensor
- 430Ω 0.1% Reference Resistor – Pre-installed for PT100 sensors
- SPI Interface – Works with any microcontroller; example code provided for temperature calculation
- 5V Safe – On-board 3.3V regulator and level shifting for use with Arduino and other 5V boards
- Screw Terminal Blocks – Two 2-pin terminals for connecting RTD sensor wires
PT100 vs PT1000
This board is configured for PT100 RTDs (100Ω at 0°C). If you have a PT1000 RTD (1,000Ω at 0°C), a different version with the appropriate reference resistor is available.
Ideal For
- Precision temperature measurement in laboratory settings
- Industrial process monitoring and control
- Food and beverage temperature logging
- Scientific instruments requiring high accuracy and repeatability
Package Contents
- 1× Adafruit MAX31865 RTD Amplifier Breakout (assembled)
- 2× 2-pin screw terminal blocks (colour may vary)
- 1× Header strip (requires soldering for breadboard use)
Jargon buster
Plain-language definitions for the technical terms used above.
- 3.3V regulator
- A 3.3V regulator is a power circuit that provides a steady 3.3 volts for parts that need that supply voltage. On a breakout board, it can let the sensor run safely even when the connected microcontroller or power source uses a higher voltage.
- ADC
- An analogue-to-digital converter reads a changing voltage and turns it into a number the microcontroller can use. It matters when connecting analogue sensors such as light, sound, or variable-resistor sensors.
- breakout
- A breakout is a small circuit board that makes a tiny or hard-to-solder component easier to connect to with standard pins. It matters because this OLED module can be wired into a microcontroller project without needing to solder directly to the display’s fine contacts.
- microcontroller
- A microcontroller is a small computer on a chip that runs your program and controls connected inputs and outputs. For this product, it is the part that reads buttons and sensors, drives the display and speaker, and communicates over Bluetooth.
- PT1000
- A PT1000 is a platinum temperature sensor whose resistance is 1000 ohms at 0°C. In this kit it lets the meter measure temperature so conductivity readings can be compensated, which matters because conductivity changes with temperature.
- RTD
- An RTD, or resistance temperature detector, is a temperature sensor that changes resistance in a predictable way as it heats or cools. It is useful in water-quality probes because accurate temperature measurement helps correct conductivity readings.
- SPI
- A fast serial communication bus often used for displays, memory cards, and sensors. It matters because SPI devices need specific pins for clock and data, plus a separate chip-select line for each device.
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