Need to measure something damp? This epoxy-coated precision 1% 10K thermistor is an inexpensive way to measure temperature in weather or liquids. The resistance in 25 °C is 10K (+- 1%). The resistance goes down as it gets warmer and goes up as it gets cooler. For specific temperature-to-resistance, check the lookup table.These are often used for air conditioners, water lines, and other places where they can get damp. The PVC coating of the wires is good up to 105 °C so this isn't good for very hot stuff.We even toss in an additional 1% 10K resistor which you can use as calibration or for a resistor divider.We have a great detailed tutorial on how thermistors work and how to use this one with both Arduino & CircuitPython!

Bosch has stepped up their game with their new BMP280 sensor, an environmental sensor with temperature, barometric pressure that is the next generation upgrade to the BMP085/BMP180/BMP183. This sensor is great for all sorts of weather sensing and can even be used in both I2C and SPI!

This precision sensor from Bosch is the best low-cost, precision sensing solution for measuring barometric pressure with ±1 hPa absolute accuraccy, and temperature with ±1.0°C accuracy. Because pressure changes with altitude, and the pressure measurements are so good, you can also use it as an altimeter with  ±1 meter accuracy.

The BMP280 is the next-generation of sensors from Bosch, and is the upgrade to the BMP085/BMP180/BMP183 - with a low altitude noise of 0.25m and the same fast conversion time. It has the same specifications, but can use either I2C orSPI. For simple easy wiring, go with I2C. If you want to connect a bunch of sensors without worrying about I2C address collisions, go with SPI.

Nice sensor right? So we made it easy for you to get right into your next project. The surface-mount sensor is soldered onto a PCB and comes with a 3.3V regulator and level shifting so you can use it with a 3V or 5V logic microcontroller without worry. We even wrote up a nice tutorial with wiring diagrams, schematics, libraries and examples to get you running in 10 minutes!

And make sure to check the tutorial for example code for Arduino and CircuitPython, pinouts, assembly, wiring, downloads, and more!

Breathe easy - we finally have an I2C VOC/eCO2 sensor in the Adafruit shop! Add air quality monitoring to your project and with an Adafruit CCS811 Air Quality Sensor Breakout. This sensor from AMS is a gas sensor that can detect a wide range of Volatile Organic Compounds (VOCs) and is intended for indoor air quality monitoring. When connected to your microcontroller (running our library code) it will return a Total Volatile Organic Compound (TVOC) reading and an equivalent carbon dioxide reading (eCO2) over I2C. There is also an onboard thermistor that can be used to calculate the local ambient temperature.

The CCS811 has a 'standard' hot-plate MOX sensor, as well as a small microcontroller that controls power to the plate, reads the analog voltage, and provides an I2C interface to read from.

This part will measure eCO2 (equivalent calculated carbon-dioxide) concentration within a range of 400 to 8192 parts per million (ppm), and TVOC (Total Volatile Organic Compound) concentration within a range of 0 to 1187 parts per billion (ppb). According to the fact sheet it can detect Alcohols, Aldehydes, Ketones, Organic Acids, Amines, Aliphatic and Aromatic Hydrocarbons. We include a 10K NTC thermistor with matching balancing resistor which can be read by the CCS811 to calculate approximate temperature.

Please note, this sensor, like all VOC/gas sensors, has variability and to get precise measurements you will want to calibrate it against known sources! That said, for general environmental sensors, it will give you a good idea of trends and comparisons.Also, AMS recommends that you run this sensor for 48 hours when you first receive it to "burn it in", and then 20 minutes in the desired mode every time the sensor is in use. This is because the sensitivity levels of the sensor will change during early use. Finally, this chip uses I2C clock stretching, and some microcontrollers/computers don't support that (e.g. Raspberry Pi)

The CCS811 has a configurable interrupt pin that can fire when a conversion is ready and/or when a reading crosses a user-settable threshold. The CCS811 supports multiple drive modes to take a measurement every 1 second, every 10 seconds, every 60 seconds, or every 250 milliseconds.

For your convenience we've pick-and-placed the sensor on a PCB with a 3.3V regulator and some level shifting so it can be easily used with your favorite 3.3V or 5V microcontroller.

We've also prepared software libraries to get you up and running in Arduino IDE or CircuitPython with just a few lines of code! Check out our tutorial for more information!

Give your next sensor project a nose for gasses with the Adafruit MiCS-5524 Gas Sensor Breakout. This breakout makes it easy to use this nice sensor from SGX Sensortech. The MiCS-5524 is a robust MEMS sensor for indoor carbon monoxide and natural gas leakage detection, it's suitable also for indoor air quality monitoring; breath checker and early fire detection.

Please note: This sensor is sensitive to CO ( ~ 1 to 1000 ppm), Ammonia (~ 1 to 500 ppm), Ethanol (~ 10 to 500 ppm), H2 (~ 1 - 1000 ppm), and Methane / Propane / Iso-Butane (~ 1,000++ ppm). However, it can't tell you which gas it has detected. 

This breakout board is not for any safety, medical or finished product usage. We're selling it for hobby education & experimentation and don't guarantee it for any other purpose! All gas sensors require calibration for precision output.

Using it is easy: Power it with 5 VDC and read the analog voltage off of the output pin. When gasses are detected, the analog voltage will increase in proportion of detected gas. When powered, the heater draws about 25-35mA. You can use the EN pin to power it off (pull it high to 5V to turn off) to conserve energy. Just make sure to wait a second after turning the heater on to make sure its all heated before taking readings.

Each order comes with one assembled and tested MiCS-5524 breakout and a bit of header. You'll need to do some light soldering to attach the header on - or you can use just plain wires.

Check out the tutorial for files, example code, diagrams and more!

This precision sensor from Bosch is the best low-cost sensing solution for measuring barometric pressure and temperature. Because pressure changes with altitude you can also use it as an altimeter! The sensor is soldered onto a PCB with a 3.3V regulator, I2C level shifter and pull-up resistors on the I2C pins.The BMP180 is the next-generation of sensors from Bosch, and replaces the BMP085. The good news is that it is completely identical to the BMP085 in terms of firmware/software - you can use our BMP085 tutorial and any example code/libraries as a drop-in replacement. The XCLR pin is not physically present on the BMP180 so if you need to know that data is ready you will need to query the I2C bus.This board is 5V compliant - a 3.3V regulator and a i2c level shifter circuit is included so you can use this sensor safely with 5V logic and power.Using the sensor is easy. For example, if you're using an Arduino, simply connect the VIN pin to the 5V voltage pin, GND to ground, SCL to I2C Clock (Analog 5) and SDA to I2C Data (Analog 4). Then download our BMP085/BMP180 Arduino library and example code for temperature, pressure and altitude calculation. Install the library, and load the example sketch. Immediately you'll have precision temperature, pressure and altitude data. Our detailed tutorial has all the info you need including links to software and installation instructions. It includes more information about the BMP180 so you can understand the sensor in depth including how to properly calculate altitude based on sea-level barometric pressure.

BMP180 Barometric Pressure/Temperature/Altitude Sensor- 5V ready (4:40)

This is a simple-to-use Carbon Monoxide (CO) sensor, suitable for sensing CO concentrations in the air. The MQ-7 can detect CO-gas concentrations anywhere from 20 to 2000ppm.

This sensor has a high sensitivity and fast response time. The sensor’s output is an analog resistance. The drive circuit is very simple; all you need to do is power the heater coil with 5V, add a load resistance, and connect the output to an ADC.

This sensor comes in a package similar to our MQ-3 alcohol sensor, and can be used with the breakout board below.

This I2C digital temperature sensor is one of the more accurate/precise we've ever seen, with a typical accuracy of ±0.25°C over the sensor's -40°C to +125°C range and precision of +0.0625°C. They work great with any microcontroller using standard i2c. There are 3 address pins so you can connect up to 8 to a single I2C bus without address collisions. Best of all, a wide voltage range makes it usable with 2.7V to 5.5V logic!Unlike the DS18B20, this sensor does not come in through-hole package so we placed this small sensor on a breakout board PCB for easy use. The PCB includes mounting holes, and pull down resistors for the 3 address pins. We even wrote a lovely little tutorial and library that will work with Arduino or CircuitPython. You'll be up and running in 15 minutes or less.Some quick specs:

Simple I2C control

Up to 8 on a single I2C bus with adjustable address pins

0.25°C typical precision over -40°C to 125°C range (0.5°C guaranteed max from -20°C to 100°C)

0.0625°C resolution

2.7V to 5.5V power and logic voltage range

Operating Current: 200 μA (typical)

This pressure sensor from Freescale is a great low-cost sensing solution for measuring barometric pressure. At 1.5 hPa resolution, it's not as precise as our favorite pressure sensor, the BMx280 series, which has up to 0.03 hPa resolution so we don't suggest it as a precision altimeter. However, it's great for basic barometric pressure sensing. The sensor is soldered onto a PCB with 10K pull-up resistors on the I2C pins.This chip is good for use with power and logic voltages ranging from 2.4V to 5.5V so you can use it with your 3V or 5V microcontroller. There's a basic temperature sensor inside but there's no specifications in the datasheet so we're not sure how accurate it is.This chip looks and sounds a whole lot like the MPL3115A2 but this is the less precise version, best for barometric sensing onlyUsing the sensor is easy. For example, if you're using an Arduino, simply connect the VDD pin to the 5V voltage pin, GND to ground, SCL to I2C Clock (Analog 5 on an UNO) and SDA to I2C Data (Analog 4 on an UNO). Then download our MPL115A2 Arduino library and example code for temperature, pressure and basic altitude calculation. Install the library, and load the example sketch. Immediately you'll have the temperature, pressure and altitude data printed in the serial console.