Oh and not to confuse anyone but when I said uppercase Mega is 1000 times, it really should have been 10000000 times. Ahh the metric system. - Chris
On Wed, Jul 1, 2009 at 4:53 PM, Chris<[email protected]> wrote: > FYI: MAh is incorrect. The correct abbreviation is mA. Lower-case m > for the milli prefix (uppercase is Mega with is times 1000 instead of > divide by 1000). > There's no H because that refers to hours. You would, however, have an > H when describing things like battery capacity because it refers to > how many hours the battery can put out power at 1 mA at the battery's > voltage rating but then they'd usually use watt-hours. > > If electricity was a waterfall, volts would be how tall the water had > to fall and amps would be how much water is actually falling. > Commonly devices are spec'ed by the voltage requirement and ampere > requirement or a wattage (watts) requirement. > For Direct Current (DC) Circuits such as the usb power, the > relationship between those three is watts equals volts times amps. > This is known a ohm's law. > > For USB devices the standard specifies 5 volts DC. If a device needs > more power the max is 500 milliamps or half an amp. > Using an unpowered usb takes 100 mA right off the top so any device > attached has a limit of 400 mA. Using a powered USB Hub (plug in the > AC outlet type) they can supply 500 mA to every port because it's not > coming from the PC's (or Braillenote's) power. > > - Chris > > On Wed, Jul 1, 2009 at 12:36 AM, Joseph Lee<[email protected]> wrote: >> Hi Kristen and list, >> I did some research about milliamp (via Google, Wikipedia and Oxford >> Dictionary), and here's what I found: >> An amp, properly called "ampere," is the unit of measurement of electric >> current. In other words, it measures how much electric current goes through >> electric circuit (more technically, conductors) in one second. A milliamp >> (MAh for short) is one thousandth of an amp. >> Er, any electrical engineers or people who are into physics, is there a >> simpler explanation... >> Hope it is simple enough. >> Cheers, >> Joseph >> -----Original Message----- >> From: Kristen Ashley Slemp [mailto:[email protected]] >> Sent: Tuesday, June 30, 2009 7:35 PM >> To: Joseph Lee; [email protected]; [email protected]; >> [email protected] >> Subject: RE: [Braillenote] External Hard Drive Again >> >> Hello Joseph and Everyone, >> IS ("milliamps") AN ABBREVIATION Or IS IT A WHOLE TERM?!? >> AND WHETHER IT'S AN ABBREVIATION OR A TERM WHAT DOES IT MEAN?!? >> THANK YOU! >> SINCERELY, Kristen >> >>> ----- Original Message ----- >>>From: "Joseph Lee" <[email protected] >>>To: "'Alex Hall'" <[email protected]>, >> <[email protected]>,<[email protected] >>>Date sent: Wed, 24 Jun 2009 20:54:11 -0700 >>>Subject: RE: [Braillenote] External Hard Drive Again >> >>>Hi Alex, >>>Actually, from my research, when USB devices are first connected >> to a host >>>(such as BrailleNote), it will start out with 100 milliamps. When >> the host >>>says to switch to higher power, then it will switch to maximum >> power output >>>- 500 milliamps. A USB hub, regardless of number ports, is >> supposed to >>>provide a total of 500 milliamps. For instance, a four-port UsB >> hub can use >>>100 milliamps to power itself, plus 4X100 milliamps for devices >> connected to >>>it. >>>I think in theory, USB hubs with devices attached will work with >>>BrailleNote. Most come with UsB plus an aC adapter for power. >>>Cheers, >>>Joseph P.S. if it is not FAT, try using a drive format software >> to convert >>>it back to fAT32. >> >>>-----Original Message----- >>>From: [email protected] >>>[mailto:[email protected]] On Behalf Of Alex >> Hall >>>Sent: Wednesday, June 24, 2009 8:32 PM >>>To: [email protected]; [email protected] >>>Subject: re: [Braillenote] External Hard Drive Again >> >>>Not a hub, but an external drive? Sure! Mine is a 320gb Seagate >>>that works perfectly. If you have a hub it should work. Both >>>ports can put out 500 milliamps between them, but, as I >>>understand it, one port could put out 500 and the other can be >>>inactive, or one can give 200 and the other 300, and so on (I >>>assume this from the wording of the manual). Therefore, the one >>>working port on your machine should give you the power required, >>>and all you need is the hub to give you both ports (data and >>>power). Hope that makes sense! >> >>>Have a great day, >>>Alex >> >>>> ----- Original Message ----- >>>>From: "Nicole B. Torcolini" <[email protected] >>>>To: "'Braillenote List'" <[email protected] >>>>Date sent: Wed, 24 Jun 2009 20:19:59 -0700 >>>>Subject: [Braillenote] External Hard Drive Again >> >>>>Some of you may remember that I got an external hard drive for >>>Christmas and >>>>was trying to hook it up to my Mpower 7.5. At the time, I gave >>>up because >>>>the bn could not provide enough power, one of my USB's being >>>broke. I now >>>>have a USB hub. The drive is 160 gb and it is not fat format. >>>Has any one >>>>had any luck with an external hard drive and a usb hub with the >>>bn? >> >> >> >>>>___ >>>>Replies to this message will go directly to the sender. >>>>If your reply would be useful to the list, please send a >>>>copy to the list as well. >> >>>>To leave the BrailleNote list, send a blank message to >>>>[email protected] >>>>To view the list archives or change your preferences, visit >>>>http://list.humanware.com/mailman/listinfo/braillenote >> >> >>>___ >>>Replies to this message will go directly to the sender. >>>If your reply would be useful to the list, please send a >>>copy to the list as well. >> >>>To leave the BrailleNote list, send a blank message to >>>[email protected] >>>To view the list archives or change your preferences, visit >>>http://list.humanware.com/mailman/listinfo/braillenote >> >>>No virus found in this incoming message. >>>Checked by AVG - www.avg.com >>>Version: 8.5.339 / Virus Database: 270.12.90/2199 - Release Date: >> 06/24/09 >>>12:49:00 >> >> >>>___ >>>Replies to this message will go directly to the sender. >>>If your reply would be useful to the list, please send a >>>copy to the list as well. >> >>>To leave the BrailleNote list, send a blank message to >>>[email protected] >>>To view the list archives or change your preferences, visit >>>http://list.humanware.com/mailman/listinfo/braillenote >> >> No virus found in this incoming message. >> Checked by AVG - www.avg.com >> Version: 8.5.339 / Virus Database: 270.13.0/2209 - Release Date: 06/30/09 >> 11:37:00 >> >> >> ___ >> Replies to this message will go directly to the sender. >> If your reply would be useful to the list, please send a >> copy to the list as well. >> >> To leave the BrailleNote list, send a blank message to >> [email protected] >> To view the list archives or change your preferences, visit >> http://list.humanware.com/mailman/listinfo/braillenote >> >> > ___ Replies to this message will go directly to the sender. If your reply would be useful to the list, please send a copy to the list as well. To leave the BrailleNote list, send a blank message to [email protected] To view the list archives or change your preferences, visit http://list.humanware.com/mailman/listinfo/braillenote
