The polargraph is a fascinating vertical plotter, that uses two small motors and gravity to move a pen over a paper, controlled by software on a computer. Actually ‘polargraph’ is the name given to it by a guy who wrote an

This is an Arduino-based battery powered air quality monitor using the optical SHARP GP2Y1010AU0F dust sensor (or its more recent version the GP2Y1014). It reports values in micrograms per cubic meter, which is also the unit of PM2.5 and PM10. Having