This is an Arduino-based Proximity Sensor circuit wired ... see the burning eye of the red LED when there is no object in the safe-zone (within 5 cm from the HC-SR04 module), and an ear-splitting beep ...

Enclosed are the ultrasonic sensor, a temperature sensor and an LED indicating the power status. On the other side of the CAT5 cable can be found an Arduino compatible board with an XBee shield ...

To supply targeting data for the launcher, an Arduino Uno uses an ultrasonic sensor pair mounted atop a servo. As the servo rotates, the returns from the ultrasonic sensor are plotted on a screen ...