In Reply to: maxtec Handi+ O2 (Nitrox) Analyzer Review posted by Chris on September 05, 2008 at 21:05:58:

If you have a rudimentary knowledge of how to wield a soldering iron and you’re still willing to twist a knob to calibrate an O2 analyzer, you build a DIY unit for under $100…

For the slightly adventuresome, I recommend plans from the “Oxygen Hacker’s Companion” (http://www.airspeedpress.com/newoxyhacker.html) which has rough plans for building your own analyzer (as well as having a wealth of information on other subjects such as Nitrox and Trimix mixing, purchasing bulk gas, cylinder tumbling, etc.), or you can get more detailed analyzer-specific information from Oxycheq’s Home Builder’s Bible for Oxygen Analyzers (http://www.oxycheq.com/Oxycheq/Analyzer-DIY-HBB.html) – note I don’t have any direct experience with this book. Lastly there’s the Heathkit-type (I’m dating myself, aren’t I?) approach from Oxycheq as well, an analyzer kit for $100: http://www.oxycheq.com/Oxycheq/Analyzer-DIY-ElCheapoII.html.
I built an analyzer based on instructions from the “Companion” years ago and every couple of years I have to replace the sensor, but that’s it. For those of you that worry about accuracy from a home-built project, the accuracy is in the sensor, not the electronics that you dink with. :)

In fact, if you really want to go bare bones, all you really need is a sensor, a common multi-meter and a cheap calculator!

Roak

Ps. Airspeed press (Oxygen Hacker's Companion) also has some good tank stickers :)

• Oxygen Hacker's Companion