On Thursday 06 December 2007, John Kasunich wrote: >Gene Heskett wrote: >> I'm still puzzled by the 10 kilohertz response listed for this device. >> WTH? Its a GMR device, and GMR is now being used as the read head in >> modern hard drives, with data rates recovered from it at what is >> effectively a 3 gigahertz rate, so why is this device so darned slow? If >> I wanted to use it, I'd sure be calling their applications engineers to >> get the skinny on why their device is several thousand times slower. I >> have done that many times in the past, and at National Semi in particular, >> have found their people very knowledgeable. AMD was at one time similarly >> helpfull with a memory problem, and I would expect any semi house to be so >> if they wanted to win the design-ins. > >The actual GMR sensor element may be quite fast, but it also produces a >millivolt level signal. The amplifier and/or comparator that turns the >small signal into a logic level is what determines the overall >bandwidth. For a hard drive, they need speed so they use fast >circuitry. For a prox switch, speed is not needed, so they use a slower >circuit. > >In fact, I bet they slow it down on purpose - a fast sensor is more >likely to respond to noise spikes. > >Regards, > >John Kasunich > Maybe John, but 10k/sec isn't fast enough to track the spindle from the steel drive gear in my 7x12 at full speed.
-- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) A career is great, but you can't run your fingers through its hair. ------------------------------------------------------------------------- SF.Net email is sponsored by: Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://sourceforge.net/services/buy/index.php _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
