What drives the main motor of a hard disk drive? Is it a constant DC voltage, or is there some more complex control?
And for the arm that moves the heads, actuated via a voice coil, what sort of input does the voice coil receive?
Thanks,
Daniele
I beleive electricitry is involve4d
They are brushless DC motors, what else do you think Dyson copied?
Analogue servo controlled by digital controller, may be PCM but I haven't been involved or interested in the internals of HDD since they had stepper motors.
dennis@home wrote in news:591849ad$0$42880 $b1db1813$ snipped-for-privacy@news.astraweb.com:
We used to understand the technolgy around us - or could study it and replicate it. Now the knowledge and ability is with so few.
I could understand a steam engine well enough to design a fundemental one. I could not design say a memory chip!
Yes, NASA figured that an alien civilisation might be able to play a gramophone record, but could they play a CD?
Given we've not managed to travel to another inhabited planet, I'd say it would be fair to assume any aliens who managed to get here would likely be rather more advanced than us?
...but could have taken an alternative route in technology.
Not even a core store?
I could design a processor (have done so in the past) but it would take rather a long time to get the fab plant designed to make it into an IC rather than TTL.
Knowing how stuff works doesn't mean you could actually make one, sometimes there just isn't the time.
Well depends on age and type. Most disc motors are servomotors in hard drives. the cheapo flopies worked a bit like tape decks, indeed many were belt driven. The head motors tend to be stepper motors of some kind.
Brian
Yes they needed stepper motors due to the sizes involved, but nowadays all sorts of techniques are in use.
Brian
Not here, moron. NASA sent it out there.
As the CD wasn't around in 1977 that problem didn't arise.
These links might help:
The raw materials would be difficult!
ISTR a figure of 40,000 years journey time to the nearest star (assuming Voyager 2 was actually headed out towards Proxima Centauri after its Neptune flyby). Given the technological capabilities required to safely traverse interstellar space, any species capable of retrieving such a probe intact would be able to decipher how to read the contents on the disk from first principles (even human civilisation after a post apocalyptical resurrection some thousand or so years on when only the basic flight information of the Voyager 2 mission may have survived with no details regarding the disk itself).
Getting back to the OP's questions, I would be asking the OP why he (or she) is interested in such information before offering anything more detailed than "No and yes" to question one and "Analogue control current" to the second.
Maybe they just have inquiring minds.
Even if aliens could decipher it, why would they? They might not have a clu e about 78s/33s/45s. If a pottery disc were dug up here with rough looking radial lines on it, we'd be more likely to think it was roughly made than t o think each line might contain data of an image.
Then there's curiosity. They might be more like dogs in that respect, and j ust not interested enough to do anything with it.
Then there's resources. There are loads of things we could benefit from doi ng. Decoding an unknown disc with lines on is a long way down the priority list.
Then there's the question of whether it would give them enough intel to con sider finding & invading earth, a planet they most likely never knew existe d.
Alien senses also might be different enough to ours that they don't make se nse of the images & sounds. 1000rpm might be beyond any speed they've used, etc etc.
NT
I'm interested in reusing old disk drive parts for - well, things I don't yet have a plan for. But the plans would depend upon what's possible.
Daniele
Or aliens might already be here, but are so alien we simply don't recognise them for what they are.
And are so alien that our potential interactions with them are limited to 'I think I have a touch of the flu'
If so, why assume a 'gramaphone record' would be obvious to them?
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