I did it and posted pictures:

Click here! Woot!

Very nice find ThoughtFix! It just takes a bit of creative thinking sometimes. Good job.

I made sure I looked at the full-size pics to verify the routing of the cables, and it all makes sense now.

Maybe a quick drawing/painting to show the cable connections could be useful. I realize you were excited to get the info posted, but I can certainly make the graphic if it may help others follow it better.

Kudos man

Okay - but this is a 2.5 megabyte, 5 megapixel image.

http://thoughtfix.com/770/usbhost-5megapixels.jpg

That should help, I hope it doesn't eat up too much of your web space.

Just a note for others, the USB hub is powered via an AC adapter, generally supplied with most USB hubs, but not always.

And the "clear" cable would typically be the one which comes with the hub, having the proper B end for the hub, and the A for the PC, or in this case the Y cable.

Even though it's just a keyboard, I still recommend using all USB 2.0 compliant cabling. Besides, ya never know when you'll use those cables for data purposes.

Again, thanks for enlightening us all...that will save me the $100+ for a bluetooth rig, at least for the time being, which eliminates the BT power drain as well.

No soldering! Where's the fun in that

Does anyone know what sort of current a typical USB keyboard uses?

That depends on the keyboard, Simon. My experience with BASIC keyboards is no more than 50 mA with LEDs on. Fancier or more feature-rich keyboards would pull more.

And what fun is that? The fun of keeping all my warranties active!

Simon:

To give you an idea, and I can't say how accurate it is, apart from looking at the mfr's specs for the keyboard (either by website or the underside), you may try checking Windows XP's device manager to get the ma rating.

Right-click on My Computer
Select Manage from the context menu
Click on Device Manager in the lefthand pane
Click on the + next to Universal Serial Bus controllers in the righthand pane
Find any of the USB Root Hub items and double-click it
Click on the Power tab at the top

Any USB peripheral connected to that port will be itemized in the lower box, indicating the name/type of device and its power requirement

I can't attest to the accuracy of XP's USB device power detection, but its a start.

I edited the post on my blog to explain the USB host mode better. Read the top (rather long) paragraph in italics.

http://thoughtfix.blogspot.com/2006/...st-method.html

Ah thanks! I didn't know about the XP feature to show the current. Most interesting. When my little USB keyboard arrives I'll check it out.

While I don't have an XP box to test, there's a very good chance it's taking the device's word for power consumption.

Every USB port is required to provide up to 100mA of current if it's actually working properly; a USB device is allowed to draw at most 100mA without asking. It can, however, ask for more - 500mA.

Thus, your operating system may happily list your USB devices as 100mA or 500mA, when really it means "permitted to take 100mA." If the numbers are nice and clean, then it's probably just doing what I describe.

There's no actual need to measure the precise current used. All USB hosts will turn off power when you draw too much - but they use a simple component that cuts power when it gets hot, rather than actually measuring it accurately.