Local Sensing, Worldwide Sharing

Over the past week we have been making a lot of progress on our bathroom intervention project, ITP WC. Macaulay and Adib have been taking the lead on the physical design and planning for our installation, including the aquaponic system. They have completed some initial prototyping work and have begun to procure the materials for the final build. More updates to come on that front from the two of them.

Marko and I have been focusing our efforts on creating the circuits that feature the gas sensors, and writing the code to share the data using Pachube. I’m happy to report that we have come a long way. We have installed our two first sensors in the ITP men’s room and we have started to feed data to Pachube (feed 11193).

Our first step was to set up the sensors on a breadboard and hook them up to an Arduino with an Ethernet shield. We started with a sensor the captures Methane and Carbon Monoxide (TGS 3870), and a second one that captures solvent vapors (TGS 2600). For building the simple circuits we got some help from an instructable article, since the datasheets from Figaro left much to be desired. We also looked at some tutorials on the arduino site to get up and running with the ethernet shield.

Getting started on Pachube required a good bit of learning. We had to get up to speed on Pachube’s API, which is not very complex but does require some time and effort. We used one of their tutorials as the basis for our code.

The last step was getting the sensors installed in the bathroom and tweaking the code to make sure we were getting reliable readings. The main change we incorporated into the code was to add functionality that takes several readings from the bathroom during a one minute period and averages those readings together uploading data to Pachube (which is done once a minute).

3 Responses to “Local Sensing, Worldwide Sharing”

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  2. Hernan says:

    hello good morning, my name is Hernan and by chance found your post that is very interesting, what happens is I got a methane gas sensor TGS3870 and I want to use a basic form but in the datasheet have a basic circuit which does not well and I understand that I need to have two classes of voltage a VC VH and somehow I do not want to damage the sensor and I is expensive.
    I would ask the instructions or guidelines for how I can feed this sensor I thank you

  3. julioterra says:

    Hernan, sorry I did not reply to you earlier. Unfortunately, I am not an expert regarding the TGS3870 sensor so I don’t have a good solution for your problem. I’ve actually encountered many issues with this sensor, for example, currently this sensor is no longer working. The best I can do is point you to the code that I wrote and that alternates the voltage as outlined in the datasheet (https://github.com/julioterra/ITP_WC_Gas_Sensing) – this code was written for an Arduino Duenovemille.

    We found that for our project this sensor was not very useful for our project. It seems to work best for threshold applications and it’s results vary considerably based on humidity and temperature. Not sure if that is helpful. Good luck with your project.

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