Building a HomeKit Compatible Laser Trip Wire With CircuitPython
This post describes how to build a HomeKit compatible electronic trip wire to detect motion. As opposed to the more common infrared motion detection, there aren’t many options for detecting movement by interrupting a line of sight between two points. There are some alternatives that use infrared diodes, but those are limited by a maximum distance of just a few inches/feet between the emitter and the receptor. This project attempts to solve that limitation by using a regular laser emitter and a photo transistor as a receptor, so that the maximum distance is only dependent on the laser’s output power and your ability of aiming it to the photo transistor from afar....