While USB supplies 5V with 100mA (500mA or more depending on the USB specificationI think) this only works for devices meaning simply putting a load across the 5V won't work.
Is there any not too complicated way to get more current out of a USB port? I wouldn't mind using an ATMega/ATTiny uC. For example the V-USB library might be an option but I'm not enough into USB to understand how a higher current can be demanded from the USB host.
At the moment I'm working on a project where I'd like to switch on an audio amplifier for a TV by the TV's USB port. I have a FRT5 5V relais which needs about 30mA but this doesn't work without chaining a USB hard drive in parallel. Using a USB flash drive or WiFi dongle on the other hand won't work which might be due to the device using up most of the supplied current itself.
Is there any not too complicated way to get more current out of a USB port? I wouldn't mind using an ATMega/ATTiny uC. For example the V-USB library might be an option but I'm not enough into USB to understand how a higher current can be demanded from the USB host.
At the moment I'm working on a project where I'd like to switch on an audio amplifier for a TV by the TV's USB port. I have a FRT5 5V relais which needs about 30mA but this doesn't work without chaining a USB hard drive in parallel. Using a USB flash drive or WiFi dongle on the other hand won't work which might be due to the device using up most of the supplied current itself.