Planet Arduino

No matter who you are,  you produce garbage of some kind or another. Two students decided they wanted to create a smart garbage can that could alert them when the can is full or even when it is stinky.

We will go on on the record: we didn’t know that an alcohol sensor could tell if your garbage is stinky, so if that works, that’s a new one on us. However, it makes a certain kind of sense because garbage ferments. We thought garbage smelled because of hydrogen sulfide and methane.

Trash cans have a tough life, so if you really want to duplicate this, you’ll probably want to mount things a bit more securely. The software, however, runs everything through a cloud service and from there can use Blynk for a phone app and IFTTT to ship things to a spreadsheet, should you care to track your garbage history statistics.

You can see in the video this is a small proof of concept can. We almost want to build one just to see if the sensor really knows when the can is smelly.

Granted, the project may not be the most practical, but it is amazing how easy it is now to build devices with a high degree of connectivity thanks to the wealth of inexpensive boards and services available.

This isn’t the first time we’ve seen Blynk. For that matter, it isn’t even our first smart trash can.

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.
}

We’re not sure if there’s enough time to get a parts order delivered, but no geeky New Year’s party will be complete without a party buzzer that doubles as a Breathalyzer. The Buzzed Buzzer hides all of the necessary bits inside of a paper and plastic party favor. We guess it only buzzes if you’re over the limit? Actually that’s not the case at all. The accuracy of the sensor used in the project really just measures the presence of alcohol and can’t quantify BAC.

A Teensy 2.0 microcontroller board drives the project. Powered by a Lithium cell, it monitors an MQ-3 Alcohol gas sensor and drives a buzzer. The components are just small enough to be hidden by the cone of the party buzzer. You can see a demonstration of this in the short clip after the jump.

This is a fun project, but we’re still big fans of getting the crowd involved with this large LED meter which is hooked up to the same style of alcohol sensor.

[via Dvice]