28
votes
Is it correct that in a hard disk both surfaces of each disk are capable of storing data?
I worked on every major disk drive manufacturer of HDD’s including our own at Burroughs for 11 yrs starting in ‘83
All 14” and 8” Head-Disk-Assemblies (HDA) used the top surface for servo feedback and ...
- 148k
24
votes
Accepted
How do hotswapping computer parts work?
It requires several features, some of which put the cost up.
These include additional transient suppression on signals, which may put additional capacitance on bus signals thus requiring additional ...
- 23.8k
14
votes
How do hotswapping computer parts work?
Reliable production level hot swap typically requires both software and hardware support.
You may need software to ensure the device is free'd so that hotswap can occur. The software needs to be able ...
- 22k
7
votes
Accepted
SATA to USB conversion: is it complex?
Yes, without going to details, it's complex, and it's because USB and SATA are completely different protocols, intended for completely different applications. They use different electrical signaling, ...
- 172k
6
votes
How do hotswapping computer parts work?
Modern hot swappable cards usually have a hotswap controller to limit the inrush current when a new card is plugged in. The issue is simply that when a card is plugged in, any bulk capacitance must be ...
- 22.6k
6
votes
What is the name of this type of pinned barrel connector?
It's a 4-pin mini-DIN connector. Here is a mating connector which you can double check for dimensions.
5
votes
Hard disk erase data
You don't "erase" as much as "write over" the data on a hard disk.
Your write head "writes" spots on the platter such that some spots are magnetized as though the spot were a magnet with the "south" ...
- 73.6k
5
votes
Is it correct that in a hard disk both surfaces of each disk are capable of storing data?
Single platter drives exist. Different manufacturers have had single platter drives in multiple standards for a long time. These by necessity require the top or bottom side to be used for storage. I ...
- 73.4k
5
votes
Why do hard disks use only one head at a time?
Turns out the question was answered in the same article, just had to read it better. Tracks nowadays are so small that they aren't aligned accurately enough across platters for heads to read multiple ...
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4
votes
Accepted
Is it correct that in a hard disk both surfaces of each disk are capable of storing data?
The read/write heads in a hard drive are not cheap. If the outermost sides of the platters were not being used for data storage, then the manufacturers wouldn't waste the money adding read/write heads ...
- 1,148
4
votes
Accepted
What servos are in hard drive write head? How are they so accurate yet so fast?
They are fast because they have a powerful rare earth magnet to propel voice-coil at one end of the moving head arm assembly around a magnetic fluid sealed bearing tower.
The feedback embedded by a ...
- 148k
4
votes
Running 3.5" Hard Drive off USB 3 (900mA / 5V)
They don't exist because they are not practical. If you need 10 watts and need to connect three USB cables just to run a single drive, and even require complex energy storage solution to get it ...
- 172k
4
votes
Can a device distinguish between USB HDD and flash drive?
As can be seen in this Microchip app note (Page 6, Table 4: "bInterfaceSubClass POSSIBLE VALUES"), the interface descriptor contains a field that differs between flash devices ("Reduced ...
- 5,103
3
votes
Powering many external 3.5" HDDs (USB) by an ATX PSU
Using ATX supplies as +12V supplies is a well established technique among model airplane enthusiasts -- basically it's the cheapest way to get +12V for charging batteries.
So -- search on that. They'...
- 47.1k
3
votes
Accepted
Is it reliable to use old computer hard disk as an external hard drive to store data?
Your drive is not reliable - & - It MAY last for a long time.
The answer to your question as the term reliable is usually understood is No!.
The drive MAY last months or even years. But there is ...
- 152k
3
votes
Accepted
Running 3.5" Hard Drive off USB 3 (900mA / 5V)
If I'm not mistaken, a USB 3.1 port can even deliver 2A (nb : it might require power negotiation first).
But basicaly, it's just a question of power : each USB port gives you 4.5W (if 900mA) or 10W (...
- 8,118
3
votes
Accepted
Why do SSDs have a limited lifespan?
A full answer would be more than I have the time or energy to do this late at night, but this should set you in the right direction with the help of duckduckgo or google (good search terms are bolded):...
- 38.5k
2
votes
Accepted
Identify component from hard drive PCB
A classic burned component on a hard drive PCB which looks like a diode, is a TVS diode.
Once common cause of such damage on 3.5" HDDs is where someone has managed to reverse its 4-pin "...
- 18.3k
2
votes
Running 3.5" Hard Drive off USB 3 (900mA / 5V)
you made the math wrong: from an USB3.0 you can get up to 5V at 900mA (4.5W), and with a converter, you can get an output of 12V at 375mA. At this point you have NO power available for the 5V rail ...
- 1,305
2
votes
What servos are in hard drive write head? How are they so accurate yet so fast?
Piezoelectric elements are used (in two stages) for the fine positioning after the voice coil has got the head in the general position of the track.
Here's a patent describing that: Piezoelectric ...
- 2,726
2
votes
How can I spin an old HDD motor?
I simply used a $3 freq generator (aliexpress.com) and a N-FET, connected one phase to 12V, the other to drain, and source to ground. Very simple. There is two issues, no self starting (I set to 60Hz ...
- 21
2
votes
Where can I find XT-IDE (8bit IDE, XTA) specifications?
Maybe it is slightly backdated...
There is no official, de-jure standard for XT IDE, but a de-facto (like ISA itself) was.
So called "XT Mode" of operation are supported by (at least) the following ...
- 1,663
2
votes
Accepted
Using HDD as an input device for Arduino
You can sense rotation using the coils from the HDD motor, but it would be much simpler to remove it and stick a rotary encoder to the drive's shaft.
Now, for the head... as said above it uses ...
- 81.7k
2
votes
Using HDD as an input device for Arduino
No. Disk drives don't work that way. The location data (track and sector numbers) are recorded on the disk itself, and the heads are positioned by a servomechanism that uses that data as feedback. The ...
- 178k
2
votes
difference between a 5 v 1a and 5v 0.65a hd
The small laptop drive consumes 5 watts of power (5V*1A).
The larger desktop drive consumes 9.25 watts of power (5V*0.65A + 12V*0.5A).
The desktop drive probably has a larger motor to spin the ...
- 8,374
2
votes
Driving a 4-wire Hard Drive Motor
You could rotate them in any mode you suggested 3 phase Delta or WYE but each is sub-optimal
If you want to run it quietly with optimum torque speed control using synchronous V/F PWM sine wave ...
- 148k
2
votes
Accepted
Hard drive won't power on, is this the reason why?
Yes, it is an inductor. Probably it is why the drive is non-functional. It is reasonable to expect that the drive will function again after you replace it, though there are no guarantees. I assume 4R7 ...
- 29.5k
2
votes
Why are hard drives not limited to sizes of a power of 2?
The answer to this is hinted at in a similar question on Superuser.
In short:
Memory DIMMs connect directly to the CPU.
There are usually multiple memory modules (but there can be only one).
...
- 4,600
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