On Fri, Nov 12, 2010 at 8:20 AM, V G wrote: > On Fri, Nov 12, 2010 at 7:53 AM, Olin Lathrop = wrote: >> Not necessarily. =A0USB voltage at the device can be from around 4.3 to = 5.5 >> volts worst case if I remember right. =A0Probably the phone contains a >> switcher to charge its battery and you don't need to be right on 5 volts= in. >> Give it a try with a variable power supply to test it. > > Yes, I'm going to experiment with voltage on my $700 phone. If Olin is correct, which he usually is on these things, then every time you plug your phone into a USB port to charge, you are "experimenting" with it. As an aside, I bought a cheap cigarette lighter inverter rated for 90W 120V, but it also had a USB port on it. Turns out the 5V on the USB plug was regulated by a 7805 with a tiny heatsink. After 5 minutes of charging my phone I smelled burning. Nothing was damaged, but the poor regulator was probably dropping 7V at 500mA-1A, while it was probably only rated for 2W. Stupid designs involving USB are everywhere, and I'm sure the phone manufacturers know this and build in some protections so they aren't getting phones returned under warranty. --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .