Gene Heskett wrote: > I possibly didn't word that as precisely as I could. But at zero speed, there > truly is no signal to condition. Only if its moving can it generate a > signal.
Not true. Hall and MR sensors are DC sensitive devices. From 1984 to 1991 I worked at a company that makes MR based encoders. I designed the signal processing for one such encoder, which used an MR sensor and bias magnet to sense gear teeth. According to info on their website ( http://www.avtron.com/tachs.htm ) it looks like they've gone away from the gear approach and now use a disk with the magnetic pattern directly imprinted on it. > Not for watching a 50 tooth gear on a headstock spindle turning 3k rpms. > That > would be a 150 kilohertz signal, so this particular device then would at the > end of its range at 200 rpm in that scenario and it still wouldn't have but a > 7.2 degree resolution. That to me is not a very useful upper speed limit, > nor truly usable resolution for high precision threading. Shaft speed is in RPM, not Hz. A 50 tooth gear at 3000 RPM = 150,000 counts per minute, which is only 2,500 Hz. Regards, John Kasunich ------------------------------------------------------------------------- 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
