The next set of parts you need to build your robot is sensors. Some are cheap and easily available, such as microphones, contact switches or LDRs, while others such as ultrasonic distance sensors ...

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 ...

and users had to have good aim to hit the sensor. These issues soon led to the introduction of the Zenith Space Command remote control, which used ultrasonic frequencies to control the TV.

Serial Kickstarter entrepreneur Patrick Thomas Mitchell has once again taken to Kickstarter to raise funds to take his new programmable Arduino ... the HC-SR04 ultrasonic ping sensor with a ...