At 2:37 PM -0700 10/23/2008, PeterH wrote: >On Oct 23, 2008, at 2:24 PM, Dan wrote: > > Each set of heads is on an arm, whoze positioning is *critical* -- >> the head has to line up exactly over the track, or it fails to read >> or write the data correctly. It's done with a step motor and >> springs. > >It's done by a voice-coil "motor", not a stepper motor, and no springs.
Ok. Guess I was thinking of one of the large HDAs that we took apart after a crash, back in my college days. It definitely had springs - two of 'em on each arm. We made wind chimes out of the platters and separator rings. :) >Positioning of a head above a track is accomplished by feedback >control, in which the track data itself is used to position the head. > >This characteristic is necessary because a voice-coil "motor" has an >infinite number of steps (that is, it has NO steps at all). hum. Not sure why I thought it was a stepper motor. Thx, - Dan. -- - Psychoceramic Emeritus; South Jersey, USA, Earth --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed Low End Mac's G3-5 List, a group for those using G3, G4, and G5 desktop Macs - with a particular focus on Power Macs. The list FAQ is at http://lowendmac.com/lists/g-list.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to [email protected] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/g3-5-list?hl=en Low End Mac RSS feed at feed://lowendmac.com/feed.xml -~----------~----~----~----~------~----~------~--~---
