20111017

republish of airwick odor detect teardown

So I accidentally deleted this post but for some reason it appeared in Reader so here is a lucky recreation: I’ve been meaning to post this for about a week now. My wife got a whole bunch of these Airwick Odor Detect things for free with her coupon voodoo. So naturally, I was compelled to take apart at least one. Here’s what I found:Inside the case, which was interestingly fastened with melted snap-tabs instead of screws or regular snaps (you’ll see if you open one, just use a knife to go in through the side and cut through them), was a built-in holder for the three included white-label AA batteries.
Also the ARNIE COMPACT3 ISS.4 controller board

the wired-in ARNIE SENSOR Rev0

board and a momentary SPST switch like the power button on lots of computers. Also, a solenoid with a built-in nozzle


was the only thing that used a connector (a JST, like LiPo’s) to connect to the controller board.So the really interesting bit was the ARNIE SENSOR Rev0 board. I did a little digging to see if anyone else had figured out what the deal was with that part. I had expected a typical gas sensor such as a http://www.sparkfun.com/products/9404 but since I didn’t know how they worked until a moment ago, I didn’t realize that I'm pretty sure they work the same way but just look radically different. I didn’t find anything documented about a teardown (didn’t look terribly long, feel free to update me on a previous posting) but I did stumble upon this: http://www.prweb.com/releases/2011/03/prweb5115684.htm which put me on the right track. Allied sensor makes some parts and this seems to be the mystery part on the board: http://www.appliedsensor.com/pdfs/APS_MOS_1109.pdf
A related sheet has this interesting note: Do not operate gas sensors in the vicinity of silicone and polysiloxanes. I’m guessing it has something to do with this document: http://www.cdc.gov/niosh/mining/pubs/pdfs/svpoc.pdf, apparently they can poison catalytic methane sensors which I feel confident now are similar. So yeah, the meat of this system is this nifty little sensor chip which has 4 leads. Two power a heater and two give you a resistance based on the chemical activity on the chip and you measure this to get air quality. Cool huh?

Update:
it looks like those crafty germans beat me to it as far back as june.  go google translate!

1 comment:

  1. I'm currently reverse engineering this exact product and I hit the jackpot with this page. Thanks so much for posting!

    ReplyDelete