I still have one of those devices to charge the ports in a CAU (or was it MAU - it's been a while. One was unpowered, the other plugged into mains) in my "Interesting things I've used in IT" box. Took a 9V battery and charged up the capacitors so when you plugged in a cable it would be detected and the client system would connect. If a port on the CAU wasn't active for too long the capacitors would lose their charge and you'd have to dig one of these out to get it back online.
Biting the hand that feeds IT
