Grinder wrote:
> vfclists wrote:
>> Is it possible to connect a 2.5in drive into 3.5 in cable on a
>> standard motherboard?
>>
>> There are some adapters that convert between 2.5 and 3.5 in
>> connections.
>>
>> What I'd like to know if it is electrically safe to do so?
>
> Since the difference is purely mechanical, you should have any problems
> with an adapter of suitable quality. I've use one like this:
>
> http://www.newegg.com/Product/Produc...82E16812119245

The 2.5" IDE is a 40 pin standard section, plus four more pins,
of which some are used for power. Both drive types would have
+5V available for a logic supply. The connector styles are
different, in that the center to center spacing of the pins
on each connector are different. The adapter Grinder linked to
above, converts between the two center to center pin spacings,
and also brings out the power pins, for connection to a power supply.

http://www.av8n.com/computer/htm/disk-pinout.htm

A 2.5", runs the motor and logic off +5V. The power is relatively
low, which is why some 2.5" drives can run off USB bus power.

A 3.5" uses +12V for the motor and +5V for logic. The peak
12V current is pretty high, at 2.5 amps on some brands. The
idling power is lower than that. Bus powering via USB or Firewire,
for a 3.5" drive, would be problematic. One Firewire solution
tried, was the idea of storing up power, so that a
ten second surge could be provided to get the disk to
spin up. But generally, a 3.5" drive needs a serious
power source, to operate properly with no issues.
The 2.5" drive has lower power requirements, making
more powering options possible. (Some 2.5" external
enclosures have two USB connectors, to provide
slightly more than 2.5W total power, while others
for more modern drives, can get by with one connector.)

The 2.5" drive may have a separate section with pins on it,
for setting master or slave. On a few laptop optical
drives, there are no master or slave pins, and the
master or slave setting is actually determine by
firmware load. Which is one stupid "innovation".
Jumpers make the job much easier, for general usage
by end users. The firmware technique only suits mass
production.

In this picture, the 4 pin jumper area is on the left, and 44 pin
connector section is on the right. And the 44 pin part is
40 pins interface plus 4 for power and other functions.
(I have no idea what the TYPE pin options are...)

http://c1.neweggimages.com/NeweggIma...149-042-03.jpg

Paul