This project is a fun exercise in simple analog design with digital interfacing and software programming. It can be assembled on a PCB using the included templates or hand-wired on a breadboard. I've included a very detailed assembly manual, lots of pictures, theory of operation, parts list, software, and complete schematics. The physical principles of an ultrasound range finder seem intuitive, but in reality a lot of unexpected things happen when using air to propagate a signal. There were a number of ultrasound sensors available commercially that are smaller and less expensive than this project. But all of these are highly integrated "black-box" devices that provide almost no explanation on how they work. To gain a detailed understanding of ultrasonic transmitters and receivers, I decided to design my own and experiment with ultrasonic wave propagation, reflection, and interference. The Ultrasonic Range Finder can reliably detect an object 1 to 10 feet away and accurately measure the distance from the sensor using digital control signals from a small computer like a Raspberry Pi or Arduino.