This is an Arduino-based Proximity Sensor circuit wired using the popular HC-SR04 Ultrasonic ranging module,used here for non-contact object detection purpose. The HC-SR04 module includes ultrasonic ...

A low-cost (~$100), do-it-yourself (DIY) ultrasonic water level sensor/datalogger has been designed, constructed, and tested for use in education, citizen/community science, and research settings. The ...

His first video deals with using with ultrasonic sensors. He found an interesting white paper that described measuring airflow with a single-path acoustic transit time flow meter.

The official Arduino Blog has this week featured a new project which demonstrates ultrasonic Arduino to Arduino communication by Brazilian maker Eduardo Zola.

Technically, the extras in the Arduino Basic Kit aren't anything a savvy consumer couldn't order piecemeal, but there's something nice about having everything ready for you in one place.