# Comparison and Experimentation with Flammable Gas Sensors ## Overview ![](https://cdn-learn.adafruit.com/assets/assets/000/063/662/medium800/sensors_cpx.mics5524.mq3.sidebyside.medres.jpg?1539870119 MiCS-5524, MQ-3 gas sensors and Circuit Playground Express.) [Hanwei](https://www.hwsensor.com/ "Hanwei")/[Winsen](https://www.winsen-sensor.com/ "Winsen Electronics") and [SGX Sensortech](https://www.sgxsensortech.com/ "SGX Sensortech") produce a range of sensors for gas detection and measurement. This project demonstrates how to use the **MQ-3** and **MiCS-5524** sensors. These are based on a _heated,_ metal oxide semiconductor which varies in resistance in the presence of a gas or vapour that can be oxidised - this includes some hydrocarbons, alcohols, ammonia and carbon monoxide. This change of sensor resistance can easily be determined from an on-board potential divider circuit producing a voltage. That voltage can be measured on an analogue ([ADC](https://en.wikipedia.org/wiki/Analog-to-digital_converter "Wikipedia: analog to digital converter")) input. Danger: In this project a Circuit Playground Express (CPX) board is used, but any board with two analogue inputs could be used. This project requires some very simple [soldering](https://learn.adafruit.com/adafruit-guide-excellent-soldering "Adafruit: Guide to Excellent Soldering") to attach 4 header pins to the [MiCS-5524 breakout board](https://www.adafruit.com/product/3199 "Adafruit MiCS5524 CO, Alcohol and VOC Gas Sensor Breakout"). ## Parts ### Part: Circuit Playground Express quantity: 1 A great sensor-packed development board with seven analog inputs and support for many languages. [Circuit Playground Express](https://www.adafruit.com/product/3333) ### Part: Adafruit MiCS5524 CO, Alcohol and VOC Gas Sensor Breakout quantity: 1 A relatively low power, 5V metal oxide gas sensor breakout board with enable line. Header pins need soldering. [Adafruit MiCS5524 CO, Alcohol and VOC Gas Sensor Breakout](https://www.adafruit.com/product/3199) ### Part: MQ-3 Gas Sensor Module quantity: 1 A common, 5V metal oxide gas sensor module. Available from many suppliers. Pinout order likely to vary. [MQ-3 Gas Sensor Module](https://www.amazon.com/MQ-3-gas-sensor/s?page=1&rh=i%3Aaps%2Ck%3AMQ-3%20gas%20sensor) ### Part: Half-size breadboard quantity: 1 Breadboard for sensors. Use the full size if you want to progress to using many sensors simultaneously. [Half-size breadboard](https://www.adafruit.com/product/64) ### Part: Small Alligator Clip to Male Jumper Wire Bundle - 6 pieces quantity: 1 Three alligator (crocodile) clips to connect to pads on CPX. [Small Alligator Clip to Male Jumper Wire Bundle - 6 pieces](https://www.adafruit.com/product/3448) ### Part: Through-Hole Resistors - 10K ohm 5% 1/4W - Pack of 25 quantity: 1 One 10k resistor. [Through-Hole Resistors - 10K ohm 5% 1/4W - Pack of 25](https://www.adafruit.com/product/2784) ### Part: Through-Hole Resistors 1k ohm 5% 1/4W quantity: 1 One 1K resistor. Two 470 ohm in series or two 2.2k in parallel would work well as a substitute. [Through-Hole Resistors 1k ohm 5% 1/4W](https://www2.mouser.com/ProductDetail/Yageo/CFR-25JR-52-1K?qs=sGAEpiMZZMu61qfTUdNhG4i669J5nKO6xow6Mp2opCk%3d) - [Next Page](https://learn.adafruit.com/gas-sensor-comparison/gas-sensor-types.md) ## Featured Products ### Adafruit MiCS5524 CO, Alcohol and VOC Gas Sensor Breakout [Adafruit MiCS5524 CO, Alcohol and VOC Gas Sensor Breakout](https://www.adafruit.com/product/3199) 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](http://www.sgxsensortech.com/). The MiCS-5524 is a robust MEMS sensor for indoor... In Stock [Buy Now](https://www.adafruit.com/product/3199) [Related Guides to the Product](https://learn.adafruit.com/products/3199/guides) ### Circuit Playground Express [Circuit Playground Express](https://www.adafruit.com/product/3333) **Circuit Playground Express** is the next step towards a perfect introduction to electronics and programming. We've taken the original Circuit Playground Classic and made it even better! Not only did we pack even more sensors in, we also made it even easier to... In Stock [Buy Now](https://www.adafruit.com/product/3333) [Related Guides to the Product](https://learn.adafruit.com/products/3333/guides) ### Half Sized Premium Breadboard - 400 Tie Points [Half Sized Premium Breadboard - 400 Tie Points](https://www.adafruit.com/product/64) This is a cute, half-size breadboard with 400 tie points, good for small projects. It's 3.25" x 2.2" / 8.3cm x 5.5cm with a standard double-strip in the middle and two power rails on both sides. You can pull the power rails off easily to make the breadboard as... In Stock [Buy Now](https://www.adafruit.com/product/64) [Related Guides to the Product](https://learn.adafruit.com/products/64/guides) ### Small Alligator Clip to Male Jumper Wire Bundle - 6 Pieces [Small Alligator Clip to Male Jumper Wire Bundle - 6 Pieces](https://www.adafruit.com/product/3448) When working with unusual non-header-friendly surfaces, these handy cables will be your best friends! No longer will you have long, cumbersome strands of alligator clips. These compact jumper cables have a premium male header on one end and a grippy mini alligator clip on the... Out of Stock [Buy Now](https://www.adafruit.com/product/3448) [Related Guides to the Product](https://learn.adafruit.com/products/3448/guides) ### Through-Hole Resistors - 10K ohm 5% 1/4W - Pack of 25 [Through-Hole Resistors - 10K ohm 5% 1/4W - Pack of 25](https://www.adafruit.com/product/2784) ΩMG! You're not going to be able to resist these handy resistor packs! Well, axially, they do all of the resisting for you! This is a **25 Pack of 10K Ω Resistors.** More specifically, they are **carbon film** , through-hole... In Stock [Buy Now](https://www.adafruit.com/product/2784) [Related Guides to the Product](https://learn.adafruit.com/products/2784/guides) ## Related Guides - [Adafruit Circuit Playground Express](https://learn.adafruit.com/adafruit-circuit-playground-express.md) - [Sound Activated Shark Mask](https://learn.adafruit.com/sound-activated-shark-mask.md) - [Makecode para la Circuit Playground Express](https://learn.adafruit.com/makecode-es.md) - [Epoxy Resin Torch Lamp with Touch Control & 3D Printed Base](https://learn.adafruit.com/epoxy-resin-torch-lamp-with-touch-control-3d-printed-base.md) - [Professor Bubbleton’s Breathing Head in a Jar](https://learn.adafruit.com/professor-bubbleton-s-breathing-head-in-a-jar.md) - [Crickit Lab Shaker](https://learn.adafruit.com/crickit-lab-shaker.md) - [Circuit Playground Simple Simon](https://learn.adafruit.com/circuit-playground-simple-simon.md) - [The MonkMakes Plant Monitor and CircuitPython](https://learn.adafruit.com/monkmakes-plant-monitor-and-circuitpython.md) - [Adafruit USB Type C Power Delivery Switchable Breakout](https://learn.adafruit.com/adafruit-usb-type-c-power-delivery-switchable-breakout.md) - [Adafruit Circuit Playground Tri-Color E-Ink Gizmo](https://learn.adafruit.com/adafruit-circuit-playground-tri-color-e-ink-gizmo.md) - [Stumble-Bot](https://learn.adafruit.com/stumble-bot-with-circuit-playground-and-crickit.md) - [New Year Countdown Clock with Circuit Playground Express](https://learn.adafruit.com/new-year-countdown-clock-with-circuit-playground-express.md) - [Compost Friend!](https://learn.adafruit.com/compost-optimization-machine.md) - [Getting Started With Steven Universe](https://learn.adafruit.com/getting-started-with-steven-universe.md) - [Zelda: Breath of the Wild – 3D Printed Bladesaw](https://learn.adafruit.com/bladesaw.md) - [Secret Hollow Book Intrusion Detector](https://learn.adafruit.com/secret-hollow-book.md)