Posted by Wayne Parham [ 64.216.177.45 ] on December 30, 2003 at 23:17:27:
In Reply to: Parthenon posted by Adrian Mack on December 30, 2003 at 19:25:59:
Do a search on the internet for "linear motors" and check out some of the industrial devices out there.
Back in the 70's, disk drives looked like washing machines. The disk pack loaded in from the top and had ten platters. So the head assembly had twenty heads and weighed a couple pounds. Moving that massive head asembly back and forth to seek a track at 200 inches per second required a seriously powerful motor. You'd typically see linear motors with magnets that weighed 100 pounds and more, and the force was enough to break your arm if it were to extend when you weren't in a safe position. Serious horsepower, and good from DC up to a few hundred Hertz.
You can find these kinds of disk drives at electronics salvagers and buy the motors pretty cheap, if you're interested. Make a helluva sub for single digit frequencies; Great for impressing your buddies!