Part 3. Making the Connections
Unplug power from your Yun before wiring up any circuit!!
Since we're only attaching one sensor, the connections are very straightforward.
Connect the SIG line of the Ultrasonic Ranger to one of the digital inputs (I used 7) using a female-male tie line. Make sure that VCC is connected to the 3.3V Power output on the Yun and GND is connected to one of the two GND connections (it doesn't matter which). The NC pin on the sensor means "No Connection" and does not need to be plugged into anything.
Power on your Yun once the ranger is wired up.