Check power require for your H/D.
Standard USB can supply 5V 500mA max (2.5Wmax).
If the power enough for your H/D I think step up converter circuit (5V to 12V) can be used.
Please help explain, if I mis-understand your requirement ?
From the question,
1. You want to design USB Cable to connect hard disk 40 GB ? Do I Right !?!
2. The HD power require both 5V and 12V supply ??
So I advice you to design converter circuit (5V to 12V, step up converter circuit) if USB port can supply the power required by your HD.
Hi!
I think so YES!
He want to use HDD like an external device, and he want to make cicuit what is convert USB standard to IDE.
I am interested to, in this stuf, thoes anyone have this kind of circuit free?!