I am trying to make my Pi (B) work as both Wi-Fi router and NAS. Setting up software for that isn't a problem for me. But all comes down to connecting USB devices and power supply issue.
Apparently USB HDD that I want to use requires separate power supply, otherwise when I plug it into Pi it does not detect disk (although I can see LED on it saying that HDD is powered up). Original cable that came with HDD box has 3 USB connectors with one being for power supply, but when I plug one end to power supply and two other to HDD and Pi (already powered from micro USB), Pi then restarts and doesn't seem to boot at all. If I do not power Pi from micro USB and connect everything, Pi boots from SD only seemingly thinking that connected HDD cable is for power only.
My question - is that possible if I solder my own USB cable where 1 end would go to wall plug (high quality 5V/1600mA), another end would go to Pi micro USB, 2nd end would go to HDDs USB to powering pins only (+5V/GND) and there would be a bridge between Pi's and HDD's +D/-D (see schematics at the bottom)? Thus I could use one wall plug and keep everything powered without backfeeding power from HDD to Pi. But I am no electronics specialist and not sure if USB will allow such tricks.
+5V/GND Wall plug ------------------ PI | | | | | | +D/-D | | HDD ---------
PS: cutting +5V line from HDD cable does work. But my Pi B rev.2 also works on same cable with drive if I use better power supply. In my case 2.1A supply was good enough to power on everything from same HDD cable.