At 10:25 PM 9/22/2009, t.piwowar wrote: >USB, being a PC technology picked up by Apple during its dark days, is >technically a mess. One can have no reasonable expectation about what >can and can't be successfully powered. I carry a portable drive with >me that works fine with FireWire. To connect it using USB I have to >carry an extra cable. First I have to plug in one cord into the drives >power socket and plug that into one USB port. Then I plug in a second >USB cord to carry data and supply additional power. The drive won't >work unless it is getting power simultaneously from two separate USB >connections. I see that as pretty shameful engineering.
No, it's just a workaround to let you power the external hard drive from the computer's 5-volt power bus when you really should power it from an external power brick, aka wall wart. The motor in the external drive requires / uses 12 volts, but will run ok on 10 volts. The USB port supplies 5 volts, which is logic voltage. You could have the doubler circuitry to double that to 10 volts, but it is cheaper to just use two different USB ports. Fred Holmes ************************************************************************* ** List info, subscription management, list rules, archives, privacy ** ** policy, calmness, a member map, and more at http://www.cguys.org/ ** *************************************************************************
