USB Relay Power Switch

youmagine

This is an external power switch for USB devices, essentially creating a "pass through" setup that includes a power boost. The downstream device on the receiving end of this device can draw as much current as an external power supply is capable of delivering - not limited by whatever the host system can provide. The switch operates straightforwardly: the host provides power to energize the coil of a 5V relay, which then switches the power from the power supply to the downstream side device. The downstream device and host are free to negotiate whatever they desire, sending data as needed, but the actual amps come directly from an external power supply rather than the host. This means the external power supply is never connected to the host and remains disconnected from the peripheral when the host is switched off or disconnected. Note that a similar setup can be achieved with a powered hub, which adheres to USB standards. In contrast, I have my doubts about whether this small device complies with these standards.