A simple device implemented using an Arduino which plays a sound whenever a person enters a room. The device, which is to be positioned at the entrance of a room, utilizes infrared sensors to do this. The device only plays a sound when it detects a person entering.

The device uses 2 infrared sensors and an infrared emitter to detect movement. The sensors detect the infrared reflection reflecting off an object passing in front of them. The device is able to tell the direction of movement of the object depending on which infrared sensor gets triggered first. A short sound will be played by the use of an active buzzer only when detecting an entry.

• Arduino Uno
• Breadboard
• Wires
• Resistors
• 2 IR sensors
• IR source
• Active Buzzer
• Button

Notes:

• The software was programmed using Arduino IDE. No additional libraries were used.
• The IR sensors were designed for interpreting signals from remote controls and are thus sensitive mostly only to 3.8kHz IR signals.
• The tone() function was used to generate this frequency for the IR emitter.

https://www.youtube.com/watch?v=9Z3g-g3RlNs

I tried to save money on components by making my project from the spare parts I got from colleagues. It took me a long time to diagnose the various issues that arose due to this. An example of this is the difference in sensitivity and detection range of the 2 IR sensors. If I were to work on another Arduino project in the future, I will definitely be buying the needed components beforehand and try to minimize improvisation.

https://forum.arduino.cc/t/how-to-create-a-38-khz-pulse-with-arduino-using-timer-or-pwm/100217/ https://docs.arduino.cc/