[Emil] got his hands on a dozen HC-SR04 ultrasonic sensors, but wasn’t too happy with their performance. Rather than give up, he reverse engineered the sensor and built an improved version. H… ...

There were a couple different sensors you could use: one was rated for something like 4″ to 8′ with a 15 degree cone, and the other was 12″ to 12′ with a 12 degree cone.

Ben Heck's been busy -- again. In the latest episode of his bi-weekly show he puts his considerable brain power to work on cycle safety. He uses Parallax ping sensors connected to an Arduino to ...