Attributes

Brand	-
Category	Robotics / STEM Teaching Tools / Sensors
Origin	-
Model Number	CJ-HR31
Sensor Type	Hygristor (Resistive)
Humidity Range	10% to 95% RH
Operating Voltage	3.3V - 5V DC
Output Signal	Analog Voltage
Response Time	< 10 seconds
Operating Temperature	-20°C to +60°C
Interface	3-Pin Header (VCC, GND, OUT)
PCB Dimensions	32mm x 14mm x 8mm
Application	Arduino, Raspberry Pi, IoT Projects

6 reviews

Anonymous

Mar 28, 2026

Rating: 5/5

Perfect for my weather station project

This sensor module works flawlessly with my Arduino Uno. The analog output is stable and responds quickly to changes in humidity. Great value for the price.

Anonymous

Mar 18, 2026

Rating: 3/5

Works but needs calibration

The sensor works, but the default reading was off by about 5%. After calibrating against a known good hygrometer, it performs much better.

Anonymous

Mar 16, 2026

Rating: 4/5

Solid performance

Used this in a prototype for a smart home system. The response time is decent, though not as fast as capacitive sensors, but perfectly fine for room monitoring.

Anonymous

Mar 12, 2026

Rating: 4/5

Good accuracy for soil monitoring

I am using this to monitor humidity in my greenhouse. It seems accurate enough for general gardening needs. Just remember to calibrate it initially.

Anonymous

Mar 10, 2026

Rating: 5/5

Easy to integrate

As a beginner, I found this very easy to wire up. There are plenty of tutorials online for the CJ-HR31. The documentation provided by the seller was also helpful.

Anonymous

Mar 06, 2026

Rating: 5/5

Bulk buy for our workshop

Bought ten of these for our makerspace. All units tested working out of the box. Consistent readings across all modules.

5 FAQ

Q: Can this be used outdoors directly in the rain?

A: No, the PCB and sensor element are not waterproof. You must house this module in a breathable, weather-proof enclosure if using it outdoors to protect it from direct water contact.

Q: Do you provide sample code for Raspberry Pi?

A: Yes, we provide a link to a GitHub repository in the product manual that includes Python scripts for Raspberry Pi and C++ examples for Arduino.

Q: Is this sensor compatible with 3.3V logic boards like the ESP32?

A: Yes, the CJ-HR31 operates on a voltage range of 3.3V to 5V, making it fully compatible with ESP32, ESP8266, and 3.3V Arduinos.

Q: What is the expected lifespan of the hygristor element?

A: Under normal operating conditions within the specified temperature and humidity ranges, the sensor element typically lasts for several years. Avoid exposing it to corrosive gases to extend its life.

Q: Does this module come with a digital output pin?

A: No, this specific model provides an analog output only. If you require a digital output (TTL), you would need to add an external comparator or choose a different model.

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