Personal computing discussed
Moderators: renee, mac_h8r1, Nemesis
ludi wrote:So, a DVD-12X drive could attempt to spin the disk in excess of 18,000 RPM at the inner tracks, which for comparison, is roughly 1.8 times the speed of a large jet turbine, and about the same as a Dremel tool operating at half-speed.
just brew it! wrote:ludi wrote:So, a DVD-12X drive could attempt to spin the disk in excess of 18,000 RPM at the inner tracks, which for comparison, is roughly 1.8 times the speed of a large jet turbine, and about the same as a Dremel tool operating at half-speed.
...and more than double the speed of a typical consumer hard drive!
You're also talking about a 20 cent piece of plastic, which isn't manufacturered to anywhere near the tolerances of a hard drive platter. It's actually kind of amazing they don't cause excessive vibration or fail (fly apart due to the mechanical stresses of being spun at 18,000 RPM) more often than they do.
ludi wrote:So, a DVD-12X drive could attempt to spin the disk in excess of 18,000 RPM at the inner tracks, which for comparison, is roughly 1.8 times the speed of a large jet turbine, and about the same as a Dremel tool operating at half-speed.
sluggo wrote:Anyway, one answer appears to be around 4.5W during spin-up. This would not include power needed by the laser for burning, but maybe someone else knows this number.
I.S.T. wrote:Well, HD platters are designed to spin at 7200/whatever RPM constantly for years on end. CD/DVD/HDDVD/Blu-Rays? Not so much. Even if they get spun faster, much faster, they also don't spin nearly as long.
just brew it! wrote:IIRC many drives have a clever arrangement of steel ball bearings and magnets inside the hub clamp, which redistribute themselves to counteract the vibration caused by unbalanced discs. So the drives are able to compensate (to an extent) for mechanical imperfections.
onlysublime wrote:wow. I learn so much from you guys...
well, if the limit of a power cable is 5 W, I guess that's the answer there.
onlysublime wrote:as for the speed, are modern drives CAV or CLV? and doesn't the outside of the disc spin faster and read data faster as a result?
I.S.T. wrote:just brew it! wrote:ludi wrote:So, a DVD-12X drive could attempt to spin the disk in excess of 18,000 RPM at the inner tracks, which for comparison, is roughly 1.8 times the speed of a large jet turbine, and about the same as a Dremel tool operating at half-speed.
...and more than double the speed of a typical consumer hard drive!
You're also talking about a 20 cent piece of plastic, which isn't manufacturered to anywhere near the tolerances of a hard drive platter. It's actually kind of amazing they don't cause excessive vibration or fail (fly apart due to the mechanical stresses of being spun at 18,000 RPM) more often than they do.
Well, HD platters are designed to spin at 7200/whatever RPM constantly for years on end. CD/DVD/HDDVD/Blu-Rays? Not so much. Even if they get spun faster, much faster, they also don't spin nearly as long.