For SOMEONE that can change things?
I was looking thru the "Playground" and under "Connecting and Powering Arduino" the sections that show the: adapter, 9v and BIG battery, all show the the plug as a 2.5 mm. Shouldn't they say 2.1 mm? I know that I'm using 2.1 mm. Could keep someone from wasting money on parts that don't work, or having problems with their power supply.
I haven't even figured out how they measure/label those jacks. It certainly doesn't seem that ONE number is enough; minimally the barrel and pin have obviously separate diameters! Grr.
Well I know the measurement is for the pin ie 2.1; 2.5 etc. Most of the time the barrel is larger for a 2.5, usually 5.5 mm. However you can get a 2.5 with a 5mm barrel. You could use this connector but you would probably have power issues since there wouldn't be good contact with the 2.1mm pin. I don't know why they don't standardize them so there's one size for 6v, 9v, 12v, 18v etc. Would be a lot less confusing.