If you’ve been following (and I know one or two of you are), then you know that FeAtHEr-Cm is my Adafruit Feather microcontroller-based approach to building scientific instrumentation for the chemistry teaching laboratory. Not only does the platform allow for inexpensive instruments to be distributed throughout a classroom (at under $50/unit, each student in an analytical chemistry lab could have their own potentiostat), but the instruments are designed so that students can understand what makes them tick.
Joining the team is the btm100 which is a spectroscopic instrument designed to perform turbidity and nephelometry experiments. These techniques help scientists explore heterogenous solutions by measuring their cloudiness, and the techniques are used widely in fields such as environmental analysis. As an added bonus, the response from turbidity/nephelometry measurements mimics that of absorption/fluorescence measurements which are commonly covered early in the chemistry curriculum, so we have a fine opportunity to build on fundamental concepts (Beer’s Law) while expanding the suite of tools students are exposed to.
No, there’s no typo in the title. While this post does describe building an instrument (a colorimeter) from scratch, it also uses the Scratch programming language to control the operation of the instrument. Read on to learn the why’s and how’s.
As one of my ‘loyal readers’ has pointed out (thanks Nick), the schematic in the MagPi has the LED in the wrong way. Be sure to connect the negative side of the LED to Ground and the positive side to GPIO25.
This post is a reprint of an article I wrote on my earlier website. I’ve tried to update the links and images, but may have missed a few.
I recently purchased the camera that attaches to a Raspberry Pi and thought about how one might be able to make a spectrophotometer using the camera as a ccd-like detector. This work is still in progress, but with relatively few steps, I was able to get an instrument up and running (and even calibrated – sort of).