Chris from Pyroelectro has posted this tutorial detailing the use of an IR transmitter and receiver break-beam pair to measure the speed of a fan. The IR components are used in conjunction with the Arduino UNO which processes the break-beam interruption counting with the result displayed on a 16×2 LCD display.
You can get the details on this project, along with schematic and Arduino code at Chris’ Pyroelectro website.
Via the contact form.
Interesting and useful. Congratulations.