Digital Tachometer or RPM (Revolutions Per Minute) counter is a tool telling the speed of some object rotation. In real world tachometers often can be fount in most cars panels. RPM indicates rotation of engines crankshaft. It usually gives some information to drivers on throttle and gear usage. So PyroElectro have built a digital RPM counter that can be used for most setups like fan motors or other spinning parts. It is based on optical detector where infrared diode is directed to receiver and moving object interrupts signal at some rate. Having this information RPM can be calculated by microcontroller.
Particularly this project was aimed for measuring RPM of PC fans. So The RPM scale is limited to 1200 – 3200 RPM. Digital RPM value is displayed on standard LCD.
Be sure to check out another great PC fan speed tester.