Arduino-based turntable tachometer using an IR sensor for input and an RS232 Shield to connect to a Phoenix Engineering Falcon to auto-adjust the speed. The Falcon works beautifully, but I fear something may not be quite right with the tachometer calculations. Based on previous experience, the speed that the tach thinks is 33.33 might actually be closer to 33.20... unless something else is wrong with my previously-accurate iPhone app, Turntabulator (which reported 33.33 on the Technics SL1200 in some of my previous videos), or with my wiring or code on the tach itself. scratches head