I've always wanted to build one of these. Maybe ill find some time to now that someone else did the hard part ;) Archive (HN): https://archive.today/V8rI7 Post (HN): https://news.ycombinator.com/item?id=40526020 From the post: >>The goal of this project is to create hardware/software capable of reading RFID tags implanted in animals. Only tags that use the FDX-B protocol are supported since they appear to be the most common. Support for HDX protocol based tags would require a significant hardware redesign that I'm unwilling to do at the moment. The EM4100 protocol, that is commonly used by RFID fobs/cards, could be supported with minor changes but that's outside the scope of this project.