2 Minute Ultrasonic Alarm

The ultrasonic sensor works by sending out sound waves and counting how long it takes for them to come back ( having been reflected from the nearest object. In this circuit the ultrasonic sensor HC-SR04 plugs straight in to the Arduin, with pins 7 and 4 being used and GND and Vcc. The distance is ca...
By: Robotix_au

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[original story: Instructables]

Instructables 19 Oct 12:29