The talented fat16lib from the Adafruit forums is building a very cool data logger.

The Arduino’s ADC is not suitable for many sensors like thermocouples or bridge sensing for pressure, strain, and force. Also it has fairly low dynamic impedance since it has no buffer amplifier. I have been looking for a simple solution to this problem for about a year. I have found a part that is accurate and very simple to use. The part is a Delta-Sigma ADC system from Microchip. I have used it on an Adafruit Proto Shield and have connected it directly to a GPS Shield to log sensor data. See below for directions for using it. I have compared the accuracy of several of these parts with a Fluke (0.09% DC V) meter. The results agree to about 1 part in a 1000 with no calibration of the ADC for measurements in the one to two volt range.

Outstanding project using our GPS shield, MintyBoost and Arduino! DIY Air quality monitoring Brent writes…

Air Quality Monitoring – Recently I had a discussion with someone from the South Riverdale Community Health Centre on Air Quality monitoring in Ontario (AQI). I learned a number of things, there are only 40 Air Quality Monitors in Ontario and they test for six key indexes. Toronto runs a slightly different test, the Air Quality Health Index (AQHI) which is a pilot programme and reports on how the Air Quality will affect your health. The AQHI test for three key indicators. Detecting three indexes sounds pretty reasonable.

Mobile Air Quality MonitorBy building my own Air Quality project I hope to be able to reproduce the AQHI results at a fraction of the price and provide instruction to enable anyone across the province a chance to build their own.

To the left is a photo of the final (but always in a state of flux) result. It is a GPS enabled device powered by two AA’s which senses Air Quality and Ozone. I am currently running tests in a variety of ways. This is a more complex setup than it has to be. Below I’ll detail both a simple setup and a complex setup.

Simple Air Quality Monitor:

• USB-Serial Connection (~$15)
• Air Quality Sensor & Ozone Sensor ($6 each)
• 2 Resistors ($.15 – I’m using a 15k Ohm)

Connect the sensors as illustrated on the Wiring.org website. Attach to a computer and upload the data to a provider such as Pachube to share with the world. (Need an invite? Message me.)

Mobile Air Quality Monitor:

• Arduino (~$45)
• GPS Sheild ($16)
• GPS ($60)
• SD-Card ($20-60 depending on size – the SD-Card library uses a FAT-16 environment, so 1GB is all you’re going to need)
• MintyBoost ($20 – 12 Hour lifespan for 2 AAs, 3 for a 9V battery)
• Air Quality & Ozone Sensor ($6 each, see above for links)
• Batteries (~$5 – I’d suggest rechargables)
• 2 Resistors ($.15)