I’m starting up a company that makes a campfire scented cologne (I’m actually producing the smoke part of the fragrance myself).  I recently ran into a problem that only open source hardware could solve: figuring out concentration using just how much light my samples absorb.

Here is a blog post with details, schematics, photos, and source code.

Here is a video we shot (with the support of Element 14) to show how the device works:

Transmissometer from Pumping Station: One on Vimeo.