HOWTO Make a USB Y Cable for Host Mode

Many smartphones or tablets support USB host mode (or On The Go mode) with an adapter. Unfortunately, a lot of those devices don't supply power to their client USB devices; you can't just plug a host mode adapter into an HP TouchPad, for example, then plug a keyboard into the host mode adapter, and expect everything to work.

I put up a video on youtube explaining how to build and use a USB Y cable to inject power to the client devices. If you'd like, you can watch it here