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#1
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Combatting Oscillation with randomness for cooling fans and harddisks.
Hello,
I just cleaned my PC today and I just noticed the fans started humming in sync. They were all running at the same speed. Perhaps the humming is cause by some dust which is on the fan blades, I am not sure, ultimately this build up probably leads to them oscillating in sync. Like soldiers walking across a bridge and causing the bridge to collapse (resonance). But I did manage to get rid of the humming by using the following trick: Since I have the antec 1200 case I can adjust the speed of each intake fan individually with each fan's speed knub. So I put the fans at slightly different speed and low and behold it got rid of the humming ! Perhaps some of the humming is also amplified by cables pressing against the case doors. Some cables are now loose since the sticky tape let go. Right now 100% of the humming is gone ! Quite marvelous. So this has given me an idea which could be applied in practice, it might be a bit risky since it takes away control/precision from the user but it's worth considering if not done already: Harddisks produced by for example hitachi/ibm could spin around a slightly random rounds per minute. So instead of having an entire rack full of harddisks spinning at exactly 5000 RPM some might be spinning at 4999 or 4998 or 5001 ot 5010, I am not sure what the speeds need to be to prevent osillation but probably very little variation is already enough to stop the oscillation. This might protect harddisk from resonance... tiny little oscilliations from harddisk racks could make the head from the disk hit the platter. How real this danger is I dont know... Perhaps bumps against the table or pickup of case is main cause of bad sectors. At least the randomness could be introduced to cooling fans. The randomness could be static/fixed... so each fan runs at slightly different speeds... Or even better it could be dynamic... if it's dynamic then buyers don't have to be afraid that they accidently bought fans or harddisk running at exact same randomness. So dynamic randomness seems to be the better idea. This entire idea is quite interesting... it's one of the first ideas I have seen so far where "exact" is bad, and "slightly off" is good Bye, Skybuck. |
#2
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Combatting Oscillation with randomness for cooling fans and harddisks.
In article . net,
"Skybuck Flying" wrote: Hello, I just cleaned my PC today and I just noticed the fans started humming in sync. They were all running at the same speed. Perhaps the humming is cause by some dust which is on the fan blades, I am not sure, ultimately this build up probably leads to them oscillating in sync. Like soldiers walking across a bridge and causing the bridge to collapse (resonance). But I did manage to get rid of the humming by using the following trick: Since I have the antec 1200 case I can adjust the speed of each intake fan individually with each fan's speed knub. So I put the fans at slightly different speed and low and behold it got rid of the humming ! Perhaps some of the humming is also amplified by cables pressing against the case doors. Some cables are now loose since the sticky tape let go. Right now 100% of the humming is gone ! Quite marvelous. So this has given me an idea which could be applied in practice, it might be a bit risky since it takes away control/precision from the user but it's worth considering if not done already: Harddisks produced by for example hitachi/ibm could spin around a slightly random rounds per minute. So instead of having an entire rack full of harddisks spinning at exactly 5000 RPM some might be spinning at 4999 or 4998 or 5001 ot 5010, I am not sure what the speeds need to be to prevent osillation but probably very little variation is already enough to stop the oscillation. This might protect harddisk from resonance... tiny little oscilliations from harddisk racks could make the head from the disk hit the platter. How real this danger is I dont know... Perhaps bumps against the table or pickup of case is main cause of bad sectors. At least the randomness could be introduced to cooling fans. The randomness could be static/fixed... so each fan runs at slightly different speeds... Or even better it could be dynamic... if it's dynamic then buyers don't have to be afraid that they accidently bought fans or harddisk running at exact same randomness. So dynamic randomness seems to be the better idea. This entire idea is quite interesting... it's one of the first ideas I have seen so far where "exact" is bad, and "slightly off" is good Bye, Skybuck. Hard disks must always be in a solid and dampening enclosure. The cheap ones that vibrate will cause rapid failure regardless of the speed of other drives. Some new variable speed fans have slightly uneven blade spacing that's supposed to reduce resonation. There's also the perfect synchronization fix: NTSC television had the vertical sweep phase locked to AC power so that magnetic fields from power wires would not cause throbbing effects in the CRT. If you had a CRT TV during the DTV transition, you probably saw the wiggle and throbbing on some stations that got rid of the phase lock. -- I will not see posts from Google because I must filter them as spam |
#3
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Combatting Oscillation with randomness for cooling fans andharddisks.
Kevin McMurtrie wrote: In article . net?, "Skybuck Flying" ? wrote: ? Hello, ? ? I just cleaned my PC today and I just noticed the fans started humming in ? sync. They were all running at the same speed. Perhaps the humming is cause ? by some dust which is on the fan blades, I am not sure, ultimately this ? build up probably leads to them oscillating in sync. Like soldiers walking ? across a bridge and causing the bridge to collapse (resonance). ? ? But I did manage to get rid of the humming by using the following trick: ? ? Since I have the antec 1200 case I can adjust the speed of each intake fan ? individually with each fan's speed knub. So I put the fans at slightly ? different speed and low and behold it got rid of the humming ! Perhaps some ? of the humming is also amplified by cables pressing against the case doors. ? Some cables are now loose since the sticky tape let go. ? ? Right now 100% of the humming is gone ! Quite marvelous. ? ? So this has given me an idea which could be applied in practice, it might be ? a bit risky since it takes away control/precision from the user but it's ? worth considering if not done already: ? ? Harddisks produced by for example hitachi/ibm could spin around a slightly ? random rounds per minute. ? ? So instead of having an entire rack full of harddisks spinning at exactly ? 5000 RPM some might be spinning at 4999 or 4998 or 5001 ot 5010, I am not ? sure what the speeds need to be to prevent osillation but probably very ? little variation is already enough to stop the oscillation. ? ? This might protect harddisk from resonance... tiny little oscilliations from ? harddisk racks could make the head from the disk hit the platter. How real ? this danger is I dont know... ? ? Perhaps bumps against the table or pickup of case is main cause of bad ? sectors. ? ? At least the randomness could be introduced to cooling fans. ? ? The randomness could be static/fixed... so each fan runs at slightly ? different speeds... ? ? Or even better it could be dynamic... if it's dynamic then buyers don't have ? to be afraid that they accidently bought fans or harddisk running at exact ? same randomness. ? ? So dynamic randomness seems to be the better idea. ? ? This entire idea is quite interesting... it's one of the first ideas I have ? seen so far where "exact" is bad, and "slightly off" is good ? ? Bye, ? Skybuck. Hard disks must always be in a solid and dampening enclosure. The cheap ones that vibrate will cause rapid failure regardless of the speed of other drives. Some new variable speed fans have slightly uneven blade spacing that's supposed to reduce resonation. There's also the perfect synchronization fix: NTSC television had the vertical sweep phase locked to AC power so that magnetic fields from power wires would not cause throbbing effects in the CRT. WRONG!!! 60 Hz only if the station was monochrome only, which pretty much disappeared in the late '50s. Color used 59.94 Hz for its vertical sweep. Hum bars were from defective filter caps, unless the power lines were within inches of the CRT and carrying high current. Even then, the 'hum would be in the form of bands f poor linearity, not a solid hum bar. -- Anyone wanting to run for any political office in the US should have to have a DD214, and a honorable discharge. |
#4
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Combatting Oscillation with randomness for cooling fans and harddisks.
On Sunday, 21 July 2013 14:31:03 UTC+8, Kevin McMurtrie wrote:
Some new variable speed fans have slightly uneven blade spacing that's supposed to reduce resonation. Fans on large hydraulic machines have had blades with unequal angles for decades. I am astonished that this has only recently appeared in computer fans. It is more of a psychological effect - the noise is less annoying although the sound power is the same. |
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