Color sensing (as well as detecting empty spaces) settled on IR-based sensors commonly used in line-following robots. You can watch the clock in action in the video embedded below just under the ...

Finally, your Arduino toolkit will be incomplete if you don't purchase some sensor ... and IR modules are indispensable for ...

An IR transmitter/receiver pair are positioned on either side of the fan. When the blade passes in between then, the receiver shuts off a transistor connected to one of the Arduino’s external ...