IR Communication


The theme for this week was networking and communications. Initially, my idea was to use a pair of sonar transmitter and receiver to communicate between two boards. The dream was to put a transmitter board on my cat’s collar, and connect the receiver to the laptop, so the laptop can automatically lock the keyboard whenever the cat is near.

All this sounded good on paper, until I looked up the hearing range of cats. They can hear up to 60 kHz! There goes my stealth 40kHz sensors...

After that, I looked into IR emitters and receivers. The lab had 880nm LEDs and phototransistors. For the sake of time, I prototyped with two arduinos.

Here’s a video of the two boards “talking” with each other. A keyboard input triggers the IR LED to start an on/off/on/off pattern for 3 seconds, which is picked up by the IR phototransistor and causes the LED on the fabduino to turn on.

Back to the cat idea, maybe I can put an IR transmitter on the cat’s collar that let’s the cat turn TVs on and off...


Too bad cats can hear 40kHz.