usb charger

hi to all ok...there are so many instructables of this argoment that i can't understand! so i have a question. what are the volt and the amp that i need for charging without destroying my usb device? thx

professorai9 years ago
There is some bit of information missing. I have accumulated 5 USB powered devices but only a couple will recharge from a battery operated USB (: The symptoms (of blackberry, motorola BT headset) is that they turn on and start charging, and immediately turn off charging. So my experiment is as follows. I cut the mini-b wire off a motorola wall charger which came with the headset, and soldered on a Female B socket (1 & 4). I found a regular USB A--Mini-B cable didn't work to charge the headset anymore. Then I soldered an A-male onto the wire with the mini-b plug. Now with this non-standard A--miniB cable, my blackberry and bluetooth headset are recharging from both the wall adapter and the battery pack.
Pacca (author) 10 years ago
i know that i need 5v but how many amp? and a linear regulator+4(or more) AA(or AAA) will be less efficienty than the project of minty boost? thx
LasVegas Pacca10 years ago
Any USB device by design will not draw more than 500mA (1/2A).