A sad story of what happened to K9 itself. Some idiot decided to rip out the vintage internals and replace it with a Rapberry Pi and an Arduino. Nothing against these for your own project, but you can't just "upgrade" something with a significant bit of history behind it. https://www.hackster.io/news/student-revives-doctor-who-s-k9...

https://en.wikipedia.org/wiki/John_Leeson