Planet Arduino

The molar mass of carbon monoxide (CO) is 28.0, and the molar mass of air is 28.8, so CO will rise in an ambient atmosphere. It makes sense to detect it farther from the ground, but getting a tall ladder is not convenient and certainly doesn’t make for fast deployment. What do you do if you don’t care for heights and want to know the CO levels in a gymnasium or a tall foyer? Here to save the day, is the Red Balloon Carbon Monoxide Detector.

Circuit.io generates the diagram and code to operate the CO sensor and turn a healthy green light to a warning red if unsafe levels are detected. The user holds the batteries, Arduino, and light while a red balloon lifts the sensor up to fifteen feet, or approximately three meters. It is an analog sensor which needs some time to warm up so it pays to be warned about that wire length and startup.

Having a CO sentinel is a wise choice for this odorless gas.

Thank you [anatza] for the tip.

If someone lobs a grenade, it’s fair to expect that something unpleasant is going to happen. Tear gas grenades are often used by riot police to disperse an unruly crowd, and the military might use a smoke grenade as cover to advance on an armed position, or to mark a location in need of an airstrike. But some gas grenades are meant to help, not hurt, like this talking gas-sensing grenade that’s a 2015 Hackaday Prize entry.

Confined space entry is a particularly dangerous aspect of rescue work, especially in the mining industry. A cave in or other accident can trap not only people, but also dangerous gasses, endangering victims and rescuers alike. Plenty of fancy robots have been developed that can take gas sensors deep into confined spaces ahead of rescuers, but [Eric William] figured out a cheaper way to sniff the air before entering. An MQ2 combination CO, LPG and smoke sensor is interfaced to an Arduino Nano, and a 433MHz transmitter is attached to an output. A little code measures the data from the sensors and synthesizes human voice readings which are fed to the transmitter. The whole package is stuffed into a tough, easily deployed package – a Nerf dog toy! Lobbed into a confined space, the grenade begins squawking its readings out in spoken English, which can be received by any UHF handy-talkie in range. [Eric] reports in the after-break video that he’s received signals over a block away – good standoff distance for a potentially explosive situation.

With the expanding supply of cheap sensors available these days, the possibilities are endless for ideas like this. It wouldn’t be that hard to add temperature, humidity and pressure sensors to the grenade, or maybe even the alcohol and ammonia sensors from this sensor suite. Add in sensors for things like particulates, vibration, and radiation, and pretty soon you’ve got a grenade that could do a lot of good.

The 2015 Hackaday Prize is sponsored by:

by codebender_cc @ instructables.com:

The MQ series of gas sensors use a small heater inside with an electro-chemical sensor. They are sensitive for a range of gasses and are used indoors at room temperature. The output is an analog signal and can be read with an analog input of the Arduino.

The MQ-2 Gas Sensor module is useful for gas leakage detecting in home and industry. It can detect LPG, i-butane, propane, methane ,alcohol, hydrogen and smoke.

Some modules have a built-in variable resistor to adjust the sensitivity of the sensor.

How to use MQ2 Gas Sensor – Arduino Tutorial – [Link]

by praveen @ circuitstoday.com:

A simple LPG sensor using arduino is shown in this article. This circuit indicates the amount of LPG in the air. The circuit sounds an alarm and trips a relay when the concentration is above a predetermined level. MQ2 is the gas sensor used in this project. MQ2 is an SnO2 based gas sensor which can sense gases like methane, propane, butane, alcohol, smoke, hydrogen etc. Since LPG primarily contains propane and butane, MQ2 sensor can be used for sensing LPG. The figure below shows the schematic and arrangement of an MQ2 gas sensor.

LPG sensor using arduino - [Link]

ICStation @ instructables.com writes:

ICStation team introduce you how to DIY this temperature & humidity & smoke alarm system based on ICStation Mega 2560 compatible with Arduino.The working voltage of this system is DC5V.It can measure the current temperature, humidity and smoke. It can display real-time data by the 1602 LCD and can realize the sound and light alarm when in the dangerous temperature and humidity. It is a simply and easily to operate monitoring alarm system about temperature humidity and smoke.

DIY Temperature & Humidity & Smoke Detector - [Link]

A lot has happened since our last article was published and to celebrate the continuance of bildr we’ll be playing with the MQ-3 Alcohol Gas Sensor. Coupled with the SparkFun Gas Sensor Breakout Board, connecting the MQ-3 to your Arduino is a breeze.

The MQ-3 is a heater-driven alcohol sensor that outputs an analog signal (usually interpreted somewhere between 150 and 1023 depending on how long you let the sensor warm up), which through the use of your Arduino code and calibration, can be interpreted for whatever use you need.

Putting The Pieces Together

When attaching your MQ-3 to the SparkFun Breakout Board, it should be noted that it doesn’t matter which way the MQ-3 alcohol sensor is pressed in. Both the A pins are electronically the same as well as the B pins. The center pins on both sides are the heater element pins. Since the circuit will be running on +5V DC it doesn’t matter which way the sensor is soldered to the board. As long as you have the SparkFun logos and pin labels facing downward, so you can still see them when the sensor is flipped over, you are good to go!

Note: Again, the MQ-3 is heater-driven so be aware that the sensor will become warm and may even emit a smell at first. This is completely normal.

Calibration: If you take your time, you can find out what values equate to specific percentages or even blood alcohol concentration in the case of a breathalyzer. You will of course need to calibrate your MQ-3 based on your specific Arduino code since sensor readings will vary. Although I can’t help with your specific calibration scenario, the best advice I can give you is to use several isopropyl alcohol bottles at different percentages for your testing. Do NOT get the sensor wet with alcohol! Simply squeeze to breathe the vapors of the alcohol into the sensor and take your readings.

Code

The Arduino code for this is very simple if you just want to view the raw data.

int mq3_analogPin = A0; // connected to the output pin of MQ3 

void setup(){
  Serial.begin(9600); // open serial at 9600 bps
}

void loop()
{
  // give ample warmup time for readings to stabilize

  int mq3_value = analogRead(mq3_analogPin);
  Serial.println(mq3_value);

  delay(100); //Just here to slow down the output.
}

winneymj writes:

My inspiration for developing this gas gauge was after purchasing a new car (Scion Xa) and wondering what MPG I was getting. After much research on ODBII protocols (Scions support CAN-BUS), and looking into open source software that already existed (OBDuino32K) I delved into my first Arduino project.

This project has taken me over a year to put together from building my own CAN-BUS shield, learning to design a circuit board, soldering SMD parts and then building my own enclosure so I could mount it in my car.

Arduino CAN-BUS OBD Gas Gauge - [Link]

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