Re: Barrel type power plugs and sockets.
Those laptop ones have three connexions, +, - and a data pin. This uses the Dallas 'One Wire' protocol and is intended to make you buy a genuine replacement adaptor rather than overloading a generic type. I wouldn't mind so much if it was only the maximum current that was communicated, but, alas, it has to say "I am a genuine HP* supply" for example.
*other makes of laptops are available, mine is an HP.
|