@dubstep_joe 452905 wrote:
Why are these things so bloody expensive? 🙁
I wanna build one of these one day: Hard disk turntable – YouTube
found a bit more info – it just happens I’ve got two busted IBM/Hitachi deskstar drives (and if they are even still made, I strongly advise that everyone stays well away from these pieces of crap). Unfortunately I definitely don’t have the star shaped screwdriver needed to get inside one – as I mentioned earlier I might have one at work but am not 100% sure – but if not I will try and buy one next time I do a CPC/Farnell order (I wanted to gut the drives anyway for data protection reasons as some of them had work data on them).
Anyway here is a pic of the underside of one of them
[ATTACH=CONFIG]151168[/ATTACH]
the connections on the orange ribbon cable is what you need to get at. The white connector it goes into has two levers on each end, push those apart and you can remove the ribbon cable. The rest of the circuit board is no longer needed – you can remove it (might be worth keeping if you ever need to recover data off a similar brand hard drive as sometimes you can do this by swapping the controllers).
its a servo controlled motor (this is how the hard drive stays at 5400 or 7200 rpm exactly) so for this motor there are two coils with 4 connections. if you turn the motor by hand, it will create two electric signals on these connections with a phase difference. (i.e one peak of electricity will be before or after the other). This means that both the speed of rotation can be worked out (by comparing the time between pulses) and the direction (as whether a pulse from phase 1 or 2 is first will depend on this).
looking at this one I reckon the easiest way to conect to it would be to solder to the 4 pads on the motor itself rather than the ribbon cable which is only about 4.5mm wide..
The rest of the circuit is here (you need other components as well as the Arduino to amplify the signal from the motor, as otherwise it is not strong enough to signal to the arduino).
TBH it isn’t the simplest of projects (this is why I’d rather buy a ready built controller!) and to get it working you’d need to have done a fair bit of electronics work including microcontroller programming and have the right test kit – though its worth starting to learn anyway if you want to do stuff like this (if you are still at school or college they might have some of the equipment)
Arduino Forum – HDDJ:hard drive as scrollwheel/turtable-like input
