Indoor air pollution reduction

I uploaded the first video here: https://www.youtube.com/WHtp4eljuDY

There have not been any updates for the last month or so because life has been getting in the way of my projectin. Sorry about that. But I have tried out the electronics and written some code. And in doing that I found that my sensor is not really all that sensitive to the stuff I'm trying to measure, PM2.5 at reasonable levels. I tend to get readings around the lower limit of its resolution unless I do something like blow the dust off the top of my computer at which point the readings jump up to more substantial values. At least that shows that the sensor works for for something. I've read up on better sensors for this application, but they tend to be very expensive, complex devices.

Fear not. Supposedly this sensor is good for things like pollen, smoke and house dust which are also a problem for many people, so I'm going to keep trying with this sensor.

By the way, if you want a very simple bit of code for using this sensor with arduino, this works: https://github.com/shlonkin/AirFilter/blob/master/AirFilterMain.ino

Somewhere amidst the flood of stuff that needs to be done I found a few minutes to sit down with a few parts, a soldering iron, and a rough idea of what I wanted to end up with(see the schematic in the last log). The results are shown below. Note the high quality holding apparatus(alligator clips attached to stiff wire that is screwed to a wood block). I like to think of soldering small components to a bit or pcb wobbling loosely in the air as a game. I like to think that because the alternative is frustration.

This right here is why I really hope I win this week's stickvice contest. I've thought of building something a little nicer to aid with soldering, but that project is far down the list. I'll just keep my fingers crossed and hope my next project log can include one of them fancy tools.

And here is the main board which was borrowed from a previous project, but with a few small modifications. I'm using it because it is set up for using an SD card. The whole thing runs at 3.3V via that LM317 regulator. It even has an audio output in case I wanted to verbally announce the dust level and play BGM inside the test apparatus like a miniature supermarket. I just need to set up some tiny aisles and registers and play James Taylor... I can tell that it's too late for me to be awake now. I'll finish it up when I find a few more minutes this weekend.

Before I start anything large I'm going to test the idea with a big cardboard box and simplified electronics. It won't have any fancy features like wireless communication and a display. It will just measure dust concentration and temperature, control a filtered fan, and log the data for later analysis.

Here is a very rough schematic. I haven't started writing code, so I don't have any pin assignments or SD card details.

The Lightblue bean and dust sensor arrived this week, both very small items. I also dug up some thermistors and cheap wireless comm modules from projects of yore. I don't know exactly what I'll be using yet, but it's time to start piecing bits together and testing the idea.

I have some concerns about the temperature sensors on the outside. Since they are so far away I don't know if something as simple as a thermistor or simple voltage-based sensor would be a good idea. Perhaps it would be better to have a simple ADC near the sensors sending a digital signal to the main unit. I'm thinking an ATtiny10 would be great for that, and I happen to have some on hand.

As for communication, that fancy bluetooth unit would be fantastic if I owned anything else capable of bluetooth communication. But I don't. Until I get my hands on something, I'll use that pair of NRF24L01+ things, or maybe just some wires.

Also, I need to thank HaD again. This project won more of the weekly contests getting me a Teensy LC and some 3D printing. This weekend I'll be refining the design a bit more, so I'll see how I can incorporate those into the project.

But before I set to work on any full scale building I want to make a little test setup. A cardboard box with a PC fan, a vent, and everything hot glued together. That means it's time for building hardware and writing code. If only there were a contest with 50 hours of free time as a prize.

Thank you HackADay

I was browsing HackADay as usual when I noticed this project on a list of winners for the weekly giveaways. Yay! I really wasn't expecting to win anything, but now that I have I am motivated to get to work on this project. And the LightBlue Bean I won seems to fit right in as the main controller as you can see in the system diagram.

Also, I purchased a dust sensor off ebay: Sharp GP2Y1010AU0F . I can't seem to find any specs about particle size, so it might turn out to be worthless as a PM2.5 sensor, but I'm crossing my fingers. There were other sensors with more complete specs, but they were more expensive. I did see this interesting page about using this sensor with an arduino and the results look kind of promising.