The HC-SR04 appeared on the market a few years back as a low-cost alternative of the Ping. [Emil] found that the HC-SR04 would work reliably on hard surfaces as far as 4 meters away from the sensor.

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 ...

Makers, developers and enthusiasts building distance related projects may be interested to know that the HC-SR04 ultrasonic sonar distance sensor is now available to purchase directly from the ...

Inside [Klaus]’ device is an Arduino Uno, an HC-SR04 ultrasonic distance sensor, and an Adafruit Wave Shield.

The HC-SR04 ultrasonic range sensor is a pretty cool pre-wired module that you actually enjoy using when you start playing with electronics, microcontrollers, and robotics. As you might have noticed, ...