Thanks !!

As far as powering a keyboard, finding where to supply the power is easy -- it's the outside pins of the USB connector. Please be careful with the polarity. If you supply power in this manner, you are supplying both the keyboard and the cable, so it should work fine.

Make sure what ever you use for power is regulated. I have seen some suggest using 4 x 1.2v rechargeables. This is dangerous. First, there is always the possibility of accidently installing alkalines, and second, I have seen rechargeables come off of the charger a little "happy". Would 6+ volts harm the 770? I don't know, but it seems like poor design, and I wouldn't try it on my 770. Finding something with a regulator in it like I did, or even designing one is not hard.

The hub is clearly optional, but due to the (current) limited size of RS-MMC cards, I wanted to be able to use a Flash drive or card reader. Besides, I used components that were available to me at the time.

I would have loved to build mine into a USB keyboard with a hub in it like was mentioned is a previous post. I also have the circuit board of the 2 port hub from an Apple USB keyboard (met with a tea accident.) I thought of adding that and a battery pack to a mini USB keyboard. This would make a nice single package, but the physical surgery to the keyboard was more than I wanted to tackle. Besides I think I will mostly just carry the hub with me. These days you can "scare up" a USB keyboard almost anyplace.

Another note. I just typed quite a bit on my 770 using an Apple keyboard (not the one that got tea on it). I had no keybounce events, so I guess it is just that mini logitech that has the problem.