*quiet* fast 3.5 scsi-2 disks
Andi
>
> I am looking for ~4GB SCSI drives (3.5" SCSI-2) that are fast (7200+ RPM)
> and *quiet*. I know of a few fast 4GB disks but I do not know how noisy
> they are (for use in a bedroom work area).
>
> Any opinions on the following (or perhaps you know of others?):
> Conner CFP4207S
> Conner CFP4217
> Fujitsu M2934S
> Micropolis MC3243
> Quantum XP34300 "Atlas"
> Quantum XP34361 "Atlas II"
> Quantum XP34301 "Grand Prix"
> Seagate ST15150N "Barracuda"
> Seagate ST34217N "Cozumel"
I wouldn't trust Quantum if my life depended on it!!! They are the
crappiest drives I've ever seen. I tried SEVEN different XP34301 Grand
Prix drives and couldn't find a good one. Two of them were marred by
bad sectors, three of them vibrated very strongly and loudly, one made
an inconsistent noise that kept changing pitch, and one was okay when
idle, but they were ALL very very loud when accessing (they sound like
popping popcorn!!!!). I had it in my bedroom and it would wake me up at
night when Windows95 would read whenever Bill Gates wanted it to.
I decided to never buy Quantum again and all three Pentiums in my home,
which are networked, have Seagate ST15150N Barracudas in them. They are
much quieter, faster than the quantums, and are all BRAND NEW. Most of
the quantums were shipped from the factory without a manual nor box, and
were slightly scratched on the top and sides, indicating previous use.
I'm sure that my vendor is not at fault for this because the Cudas came
with boxes, manuals, and were brand spankin' new and shiny! I suggest
the cudas.
The best deal I've found is at Insight. They want $1199 but my sales
rep, Scot Leith, sold them to me for below that. Negotiate a deal. His
email is scot_...@insight.com and his phone number is 1-800-805-2675.
I am absolutely not affiliated with insight if by this message you get
that impression. I am a fifteen year old student who has researched the
market and I believe that Insight is the best.
Wish you luck in finding a good drive!
Regards,
Andi Baritchi
an...@airmail.net
Thor Lancelot Simon
>Aydin Edguer wrote:
>>
>> I am looking for ~4GB SCSI drives (3.5" SCSI-2) that are fast (7200+ RPM)
>> and *quiet*. I know of a few fast 4GB disks but I do not know how noisy
>> they are (for use in a bedroom work area).
>>
>> Any opinions on the following (or perhaps you know of others?):
>> Conner CFP4207S
>> Conner CFP4217
>> Fujitsu M2934S
>> Micropolis MC3243
>> Quantum XP34300 "Atlas"
>> Quantum XP34361 "Atlas II"
>> Quantum XP34301 "Grand Prix"
>> Seagate ST15150N "Barracuda"
>> Seagate ST34217N "Cozumel"
>
>I wouldn't trust Quantum if my life depended on it!!! They are the
>crappiest drives I've ever seen. I tried SEVEN different XP34301 Grand
>Prix drives and couldn't find a good one. Two of them were marred by
I tried fifteen Grand Prix drives and didn't find a bad one. YM, obviously,
MV. It seems fairly clear to me that you were A) dealing with an unscrupulous
vendor, however, and B) have a rather unusual definition of a "good one".
>bad sectors, three of them vibrated very strongly and loudly, one made
How many bad sectors? Just a few aren't really out of the ordinary, you know.
Of course, since you say the drives you got looked like they'd been previously
used, they could have been returned because they had problems with too many
bad sectors; we got a few evaluation Conner drives by mistake once which in
fact had exactly this problem. It was fairly obvious, once we tried to use
them. :-)
Vibration and noise are annoying, but hardly indicate a "bad" drive, in the
usual sense of the word, particularly if the vibration and noise are common
to most drives of the type in question.
>an inconsistent noise that kept changing pitch, and one was okay when
>idle, but they were ALL very very loud when accessing (they sound like
>popping popcorn!!!!). I had it in my bedroom and it would wake me up at
They certainly are loud, I'll give them that. And they do make a fascinating
variety of noises. Definitely not the best choice if silence is key.
>night when Windows95 would read whenever Bill Gates wanted it to.
>
>I decided to never buy Quantum again and all three Pentiums in my home,
>which are networked, have Seagate ST15150N Barracudas in them. They are
>much quieter, faster than the quantums, and are all BRAND NEW. Most of
Did you actually measure that they're faster than the Quantum drives? On
writes? I find that they read a hair more slowly than the Grand Prix units
but write at only about half the speed. They certainly don't perform any
better -- and of course for what a ST15150 costs from most vendors, one can
buy disks which are somewhat faster than the Grand Prix.
>the quantums were shipped from the factory without a manual nor box, and
You ordered directly from the factory? How did you pull that off, for an
order of only five units?
Any vendor who shipped me hard drives with no box, no data sheet, and
scratches on top indicative of prior use would not be a vendor I'd ever do
business with again. Are you really claiming that Quantum is reselling used
units as new? I don't believe you.
Most hard drives don't come with a manual, really. Some mail-order houses
pull the maufacturers' data sheets, for some reason, which is really
irritating. Again, hardly Quantum's fault.
>were slightly scratched on the top and sides, indicating previous use.
>I'm sure that my vendor is not at fault for this because the Cudas came
>with boxes, manuals, and were brand spankin' new and shiny! I suggest
>the cudas.
I don't. They're quieter than the Grand Prix drives, but much louder than the
Atlases, which cost about the same. According to my fairly extensive tests,
both Quantum units were significantly faster than the Seagates. In fact, the
Seagates had the worst long-write performance of any of the 7200RPM drives I
tested.
>The best deal I've found is at Insight. They want $1199 but my sales
>rep, Scot Leith, sold them to me for below that. Negotiate a deal. His
>email is scot_...@insight.com and his phone number is 1-800-805-2675.
I find that Insight/HDI are almost always the most expensive place to buy
hard drives. Even if they knocked $100 off that $1199 price for you, which
I doubt that they did, they're still $150 above what at least one other vendor
is selling 4GB Barracudas for, and they're still, except for the Atlas, the
most expensive of all of the drives mentioned in the original message.
Barracudas also have absolutely stunning airflow requirements for proper
cooling. Do you have your Barracudas wedged between two fans? If not, don't
expect them to last long.
>I am absolutely not affiliated with insight if by this message you get
>that impression. I am a fifteen year old student who has researched the
>market and I believe that Insight is the best.
For what Insight wants for an ST15150, you could have your pick of any 4GB
disk made by any other manufacturer, period. There are much better options out
there than a two-year-old design which was a good performer when it was first
introduced, but had significant drawbacks.
--
Thor Lancelot Simon t...@rek.tjls.com
love is an angel disguised as lust
Aydin Edguer
Paul Rubin
Aydin Edguer <edg...@ces.cwru.edu> wrote:
>
>I am looking for ~4GB SCSI drives (3.5" SCSI-2) that are fast (7200+ RPM)
>and *quiet*. I know of a few fast 4GB disks but I do not know how noisy
>they are (for use in a bedroom work area).
> Seagate ST15150N "Barracuda"
This one is noisy for sure. I don't know about the others.
However, all 7200 rpm 4 GB discs appear to require forced air
cooling (i.e. you need a fan blowing air over the drive, NOT just
the normal fan in your PC's power supply). That is an additional
source of noise.
I got rid of my 7200 rpm ST15150N Barracuda and got a 5400 rpm
ST15230 Hawk (with slightly slower transfer speed) for this reason.
The Hawk drive is also fairly noisy, unlike what I've been told
about its 2.1 GB low-profile counterpart. If I had it to do over
I might have gotten the 2.1GB drive. Alternatively, low-profile
4 GB drives might be available pretty soon.
Paul Rubin
Thor Lancelot Simon <t...@rek.tjls.com> wrote:
>Conner.
>
>I've heard a rumor that they're being bought by Seagate. Is this complete
>nonsense, or rooted in fact? Anyone know?
It's not a rumor. Conner was bought by Seagate a few months ago,
and it was widely reported in the news.
Pascal Walch
>
>I am looking for ~4GB SCSI drives (3.5" SCSI-2) that are fast (7200+ RPM)
>and *quiet*. I know of a few fast 4GB disks but I do not know how noisy
>they are (for use in a bedroom work area).
>
> Quantum XP34301 "Grand Prix"
This one is VERY loud for sure. While restoring lots of small files,
the drive will make you crazy. Don't forget to consider IBM Ultrastor
XP and 2XP drives from IBM. They are a bit more expensive but very
fast and very quiet.
********************************************************
* LIFE IS WHAT HAPPENS WHILE YOU'RE MAKING OTHER PLANS *
********************************************************
Thor Lancelot Simon
Doug Siebert <dsie...@icaen.uiowa.edu> wrote:
>t...@panix.com (Thor Lancelot Simon) writes:
>
>>I'm pretty sure that the Barracudas have write caching disabled because they
>>don't have "safe" caches that can use the mechanical energy of the spindle to
>>flush if the power goes out. Most more modern designs which ship with write
>>caching turned on do, in fact, have this, AFAIK.
>
>
>Does anyone know of any disks that really *do* have a way of flushing out
>their entire cache? AFA*I*K, *no* drives on the market can do this. Think
>about it -- if you have even a 256K cache, it could take up to a second to
>write everything out if you had a 512 byte block to write in 512 different
>tracks. On drives like the Barracuda that have 1M or 2M caches, it could
>potentially take several seconds. I wonder how big of a capacitor worst case
>would require? Certainly could never ever be done with mechanical energy.
Per the earlier discussion of the topic here, most of the drives which ship with
write caching turned on do all kinds of tricks to ensure that they invalidate
the cache when they do things like long seeks which would make them unable to
flush in the event of a power hit.
>Some drives ship with write cache enabled because people will get them and
>their silly little DOS benchmarks will show them to be very very fast, they'll
>tell their friends who have much lower results on their uncached drives and
>get them to want to buy brand X drives next time.
I don't know if you're referring to me or not, but I don't do "silly little
DOS benchmarks", and I've been a fairly vocal critic of large, unflushable
write caches here in the past.
Darryl Okahata
> I wouldn't trust Quantum if my life depended on it!!! They are the
> crappiest drives I've ever seen. I tried SEVEN different XP34301 Grand
> Prix drives and couldn't find a good one. Two of them were marred by
You're using the wrong 4GB Quantum drive. You should have gotten
the Atlas. I've got the XP34300 Atlas, and it's a wonderful drive.
> I decided to never buy Quantum again and all three Pentiums in my home,
> which are networked, have Seagate ST15150N Barracudas in them. They are
> much quieter, faster than the quantums, and are all BRAND NEW. Most of
> the quantums were shipped from the factory without a manual nor box, and
> were slightly scratched on the top and sides, indicating previous use.
> I'm sure that my vendor is not at fault for this because the Cudas came
> with boxes, manuals, and were brand spankin' new and shiny! I suggest
> the cudas.
I suggest getting a new vendor. If some vendor shipped me some
apparently-used drives when I paid for brand-new ones, I'd immediately
drop-kick the vendor and go somewhere else. Think about it. Really
... think ... about ... it.
Also, I hope that you're keeping your Barracudas cool. Barracudas
need special cooling; they weren't originally designed for use in PCs,
but that is where they are (obviously) being sold. I've got a 12550
Barracuda, and it runs warmer than my Atlas (and, yes, my Barracuda does
have special cooling -- it runs cool enough to be touched by *any* part
of the body ;-).
> The best deal I've found is at Insight. They want $1199 but my sales
You've got to be kidding. While Insight appears to be a
reliable/decent place, their prices do not appear to be good,
considering their "reliability". [ Given that they have what I
currently perceive to be decent customer support, their prices seem
higher than those places with similar customer support. ]
-- Darryl Okahata
Internet: dar...@sr.hp.com
DISCLAIMER: this message is the author's personal opinion and does not
constitute the support, opinion, or policy of Hewlett-Packard, or of the
little green men that have been following him all day.
Darryl Okahata
> I don't. They're quieter than the Grand Prix drives, but much louder than the
> Atlases, which cost about the same. According to my fairly extensive tests,
> both Quantum units were significantly faster than the Seagates. In fact, the
> Seagates had the worst long-write performance of any of the 7200RPM drives I
> tested.
My 12550 Barracuda came with write-caching disabled, whereas my
34300 Quantum Atlas came with write-caching enabled. I wonder if that
could explain the speed difference? I haven't been brave enough to
enable write-caching on my Barracuda, and so I don't know how much of a
difference it would make.
[ To anyone else reading this: please do not ask me how to
enable/disable write-caching on a disk drive. There aren't any good
tools for doing so, unless you've got a PC Unix like FreeBSD, and it's
just too easy for novices to wipe out their hard disks. ]
Darryl Okahata
> I'm pretty sure that the Barracudas have write caching disabled because they
> don't have "safe" caches that can use the mechanical energy of the spindle to
> flush if the power goes out. Most more modern designs which ship with write
> caching turned on do, in fact, have this, AFAIK.
>
> One more way the Barracudas suffer from being an older design than the rest of
> what's now on the market.
While this is certainly a valid concern, I don't think most people
need to worry about power failures. Power failures/problems are pretty
rare (for most people), and, for those areas where it is or can be a
problem, I think you're best off getting a decent UPS.
mi...@ultranet.com
But it is a 2GIG and it bench marked faster than the Seagate
Barracuda. I Had my choice between 3 used 2 gig drives.
Seagate 12550N
Seagate 12550W
IBM.
The 12550N was flakey, didn't seem to remap back blocks unless
done through a verify.
The 12550W was only 5% faster and the loudest drive I ever heard.
The IBM which I really didn't want turned out to be 2.5% faster than
12550N, ran cooler, and is whisper quiet. The loudest thing now
is my power supply fan. I test with WinBench 95.
This drive has renewed my feeling towards IBM equipment in general.
Paul Rubin
Doug Siebert <dsie...@icaen.uiowa.edu> wrote:
>t...@panix.com (Thor Lancelot Simon) writes:
>
>>don't have "safe" caches that can use the mechanical energy of the spindle to
>>flush if the power goes out. Most more modern designs which ship with write
>>caching turned on do, in fact, have this, AFAIK.
>
>
>their entire cache? AFA*I*K, *no* drives on the market can do this. Think
>about it -- if you have even a 256K cache, it could take up to a second to
>write everything out if you had a 512 byte block to write in 512 different
>tracks. On drives like the Barracuda that have 1M or 2M caches, it could
>potentially take several seconds. I wonder how big of a capacitor worst case
>would require? Certainly could never ever be done with mechanical energy.
1. As someone mentioned, drive firmware invalidates the cache if it
has to do a long seek which would prevent the cache from being flushed
on power failure.
2. Back in the old days, some disk drives actually contained rechargeable
batteries, in order to retract the heads if the power failed. I don't
know of any modern disks like that, though.
3. Re capacitor size: say the peak power is 20 watts and it's needed
for 2 seconds, so that's 40 joules of energy. Capacitors hold E = 1/2 C V^2
so if V = 12 volts and E = 40 joules, C = 2E/V^2 = 80/144 = 0.55 farads.
I think such capacitors exist, but they are pretty big, probably too
big to use on the circuit board of a 3.5" drive.
Mika Kortelainen
>The IBM which I really didn't want turned out to be 2.5% faster than
>12550N, ran cooler, and is whisper quiet. The loudest thing now
>is my power supply fan. I test with WinBench 95.
Does anyone know about IBM's DORS-32160? It's a 5400RPM drive
but according to IBM's WWW page it's quite fast (although I don't
know how reliable source that is ;-)
I just started to wonder which IBM it was that was discussed here
some time ago... that drive which makes some 'automatic checks' every
now and then. I don't want that kind of drive so I'd like to know
if it was DORS or not (my news server doesn't carry that old articles
so I cannot check it).
By the way, is Barracuda 2LP hot or not? Does it also need special
cooling like older ones? It might be fast drive, too.
Mika Kortelainen
Alexander Goykhman USG
>
>I am looking for ~4GB SCSI drives (3.5" SCSI-2) that are fast (7200+ RPM)
>and *quiet*. I know of a few fast 4GB disks but I do not know how noisy
>they are (for use in a bedroom work area).
I have a 2Gb Fujitsu, and it is very quiet.
mi...@ultranet.com
>dsie...@icaen.uiowa.edu (Doug Siebert) writes:
>>Does anyone know of any disks that really *do* have a way of flushing out
>>their entire cache? AFA*I*K, *no* drives on the market can do this. Think
>>about it -- if you have even a 256K cache, it could take up to a second to
>>write everything out if you had a 512 byte block to write in 512 different
>>tracks. On drives like the Barracuda that have 1M or 2M caches, it could
>>potentially take several seconds. I wonder how big of a capacitor worst case
>>would require? Certainly could never ever be done with mechanical energy.
>
>The Barracuda LP's have only 512K of cache. No drives, not even the
>Atlases, which were originally advertised to have 2MB of cache, have 1MB
>or 2MB of cache, AFAIK (let me which ones do if they exist; I'd be
>interested in getting some).
I found the Non LP Barracuda to not run nearly as hot
as I was warned. I was warned of burning my hand if I
touched it. This may be true in a small low profile case
but in a full tower with a empty bay above and below
it ran warm to the touch. No special fans.
Darryl Okahata
> The Barracuda LP's have only 512K of cache. No drives, not even the
> Atlases, which were originally advertised to have 2MB of cache, have 1MB
> or 2MB of cache, AFAIK (let me which ones do if they exist; I'd be
> interested in getting some).
Wrong. The 4GB Quantum Atlas has 2MB cache (well, actually, it has
2MB RAM, of which part is used for a firmware scratch pad, and the rest
is used for cache). The 2GB Atlas has a 1MB cache. Check out the Atlas
specs on Quantum's web page for more info:
http://www.quantum.com/products/atlas/
Surfer (William) Lee
>Does anyone know of any disks that really *do* have a way of flushing out
>their entire cache? AFA*I*K, *no* drives on the market can do this. Think
>about it -- if you have even a 256K cache, it could take up to a second to
>write everything out if you had a 512 byte block to write in 512 different
>tracks. On drives like the Barracuda that have 1M or 2M caches, it could
>potentially take several seconds. I wonder how big of a capacitor worst case
>would require? Certainly could never ever be done with mechanical energy.
Chris Pirih, proverbs at wolfenet dot com
| > Seagate ST15150N "Barracuda"
|
| This one is noisy for sure. I don't know about the others.
|
| ST15230 Hawk (with slightly slower transfer speed) for this reason.
|
| The Hawk drive is also fairly noisy, unlike what I've been told
| about its 2.1 GB low-profile counterpart. If I had it to do over
| I might have gotten the 2.1GB drive. Alternatively, low-profile
| 4 GB drives might be available pretty soon.
I replaced my Barracuda with two Hawk2LP (1GB) drives, and they are
much, much quieter. The 1GB Hawks are the quietest drives I've ever
found -- you can barely hear them when they're doing full-stroke
seeks.
---
chris
Daniele Orlandi
> ...
> 3. Re capacitor size: say the peak power is 20 watts and it's needed
> for 2 seconds, so that's 40 joules of energy. Capacitors hold E = 1/2 C V^2
> so if V = 12 volts and E = 40 joules, C = 2E/V^2 = 80/144 = 0.55 farads.
> I think such capacitors exist, but they are pretty big, probably too
> big to use on the circuit board of a 3.5" drive.
Well, I have a 1 Farad capacitor that is big as a coin. It seems to be a capacitor
since the charge and discharge current is like any other capacitor I ever used. The
maximum voltage is 5 Volts. It is used to retain CMOS memory for 3-6 months.
I have also a bigger 3.3 Farads model.
I belive that they actually are capacitors. I don't know if they are suitable for
high current applications, but since they surprised me, my friends and my electronic
teacher too, I wanted to make you know that they really exists.
Bye !
Daniele
Sandy Mustard
>
> I have two IBM hard drives, exactly the
> IBMRAID 0664M1H (2 GB)
> IBM 0663L12 (1 GB)
>
> They seem to be very fast, they aren't quiet at all and I belive thay are old
> models. Where is the IBM hard disks page where I can find information on them ?
Try http://www.almaden.ibm.com:80/storage/oem/hardddr.htm
Chao
Sandy Mustard
SDRC
George Pontis
>
> My 12550 Barracuda came with write-caching disabled, whereas my
> 34300 Quantum Atlas came with write-caching enabled. I wonder if that
> could explain the speed difference? I haven't been brave enough to
> enable write-caching on my Barracuda, and so I don't know how much of a
> difference it would make.
>
> [ To anyone else reading this: please do not ask me how to
> enable/disable write-caching on a disk drive. There aren't any good
> tools for doing so, unless you've got a PC Unix like FreeBSD, and it's
> just too easy for novices to wipe out their hard disks. ]
>
For those that have an Adaptec controller and EZ-SCSI, the "SCSI Explorer"
utility has a cache tab that shows the status of the cache, and allows one
enable & disable write caching. Worked nicely on an ST-32550 Barracuda II ...
George Pontis
>
> By the way, is Barracuda 2LP hot or not? Does it also need special
> cooling like older ones? It might be fast drive, too.
>
When idling the drive runs very cool, barely above the
temperature of the case to which it is mounted. With out any fan
at all. I never tried to concoct a torture seek test to see how
hot it would get in a very demanding application. (Doesn't "LP"
stand for Low Power ?)
-T.SHIU
>In article <4hqgfl$9...@madeline.ins.cwru.edu>,
>>
>>I am looking for ~4GB SCSI drives (3.5" SCSI-2) that are fast (7200+ RPM)
>>and *quiet*. I know of a few fast 4GB disks but I do not know how noisy
>>they are (for use in a bedroom work area).
>
>
>This one is noisy for sure. I don't know about the others.
>
>cooling (i.e. you need a fan blowing air over the drive, NOT just
>the normal fan in your PC's power supply). That is an additional
>source of noise.
>
>ST15230 Hawk (with slightly slower transfer speed) for this reason.
>
>The Hawk drive is also fairly noisy, unlike what I've been told
>about its 2.1 GB low-profile counterpart. If I had it to do over
>I might have gotten the 2.1GB drive. Alternatively, low-profile
>4 GB drives might be available pretty soon.
All seagate drives that I have used so far tended to be noisy and more
over time. Interesting enough, my Hwak ST31200N is very quiet until
recently. Along with that, the drive started to have a lot of data error.
+-----------------------------------+
| Tyrone Shiu |
| Email: tyr...@hogpb.ho.att.com |
| |
| The above opinions are mine and |
| do not reflect the official |
| opinion of AT&T. |
+-----------------------------------+
Mika Kortelainen
>When idling the drive runs very cool, barely above the
>temperature of the case to which it is mounted. With out any fan
>at all. I never tried to concoct a torture seek test to see how
>hot it would get in a very demanding application. (Doesn't "LP"
>stand for Low Power ?)
Hmm, I have always thought it means "Low Profile"... but I'm not
sure.
Mika Kortelainen
Gary M. Watson
It definitely does stand for "Low Profile". They don't get too hot
idle -- the 1/3rd stroke or butterfly seeks really burn the
electrons, however. Damn nice drive, IMO, but you have to design
the enclosure properly.
--
Gary M. Watson, EE etc. tr...@netcom.com
Sigma-Trimm Technologies, A Division of Robroy Industries
Las Vegas, NV 89119 Phone: (800) 423-2024 x2115
New T-1 SGI Server!! ga...@trimm.com and http://www.trimm.com (Under Constr.)
Joachim Michely
Yes these are capacitors but they are only for low current applications. They
are called "GoldCaps" because they are made with a "gold" foil. There primary
use is as mention for CMOS backup ( without a battery ) because of there very
low selfdischarge.
Capacitors for high current application are "electrolytic capacitors" and they
are indeed very big.
>
> Bye !
>
> Daniele
>
Joachim Michely, Steinkaule 50, 53757 St-Augustin, Germany
Voice/Fax : ++49-(0)2241-337938 ( and answering machine )
Internet : mic...@nemeter.dinoco.DE
CompuServe : 100024,2476
Andrew Gabriel
p...@netcom.com (Paul Rubin) writes:
>
>2. Back in the old days, some disk drives actually contained rechargeable
>batteries, in order to retract the heads if the power failed. I don't
>know of any modern disks like that, though.
I have a Western Digital Piranha (now rather old) which stops the
platters dead on removal of power, with quite a bang! The old CDC
8" and 14" drives had a large capacitor to retract the heads on power
fail, but these disks never allowed the heads to land on the platters
anyway. I believe both of these complete the writing of any sector in
progress at the time, to avoid a CRC error. I would expect newer disks
could write a lot more.
>
>3. Re capacitor size: say the peak power is 20 watts and it's needed
>for 2 seconds, so that's 40 joules of energy. Capacitors hold E = 1/2 C V^2
>so if V = 12 volts and E = 40 joules, C = 2E/V^2 = 80/144 = 0.55 farads.
>I think such capacitors exist, but they are pretty big, probably too
>big to use on the circuit board of a 3.5" drive.
It would probably be better to use such a capacitor to battery-back
the cache until power was restored. The low power CMOS RAMS can go
months in standby mode on specially designed capacitors now.
--
Andrew Gabriel Home: And...@cucumber.demon.co.uk
Consultant Software Engineer Work: Andrew....@net-tel.co.uk
David A Willmore
>Yes these are capacitors but they are only for low current applications. They
>are called "GoldCaps" because they are made with a "gold" foil. There primary
>use is as mention for CMOS backup ( without a battery ) because of there very
>low selfdischarge.
>Capacitors for high current application are "electrolytic capacitors" and they
>are indeed very big.
NEC makes these--along with a few others. They are made of activated carbon--
as it has such a huge surface area, their capacity is quite large. The
drawback is that they have a fairly high internal resistance, hence they
don't do too well for high current or AC applications. They come in several
sizes and in 12V, 5V, and 3.3V ratings.
Cheers,
David
Daniele Orlandi
I belive that the high internal resistance you see when they are discharged is
intentional and used for short-circuit protection. When you charge such capacitors,
you have the same current for a 1-2 Ohms internal resistance. How do you justify
this ? I belive that a protection diode is used.
However, also removing the internal diode, these capacitors aren't suitable for
high current applications.
--
Daniele
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Daniele Orlandi
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Italy FAX: ++39(2)29510943
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