DIY mass spectrometer measures potassium in dietary salt substitute

How to build and operate a simple mass spectrometer. Please ask questions in the comments, as always. (I had to re-upload this video to fix the ending --I’m very sorry if your early comments were lost!) Scientific American article: $ is a good value for the entire back issue in plain PDF format, and an example of a publisher being reasonable. I’m happy to support this. Original Dewdney paper: ://doi.o