I worked on a big CNC lathe equipped with the GE Inductosyn scales and I found a company who sells an adapter/interface for those...
I thought we might have to retrofit the lathe, but for now the existing controls work... about as well as 1984 vintage controls can work... ;-) http://vegacnc.com/html/vega2875501.htm I believe that I obtained some pricing on those and they seemed reasonable. The GE scales on the machine I worked on were very accurate. Dave (Dave911 on the IRC) On 4/11/2010 3:31 PM, sam sokolik wrote: > there are actually 4 coils. Each head has 2 shielded cables coming from > the head - each cable has 4 conductors + shield. At the controller - > the 2 coils on each cable are hooked together to form a center tapped > setup. (agian - if I have it right - they excite the 2 outside > connections of the 2 center tapped hookups - then the center taps get > summed together and shaped. this from trying to read the desciption on > the schematic I scanned - plus you can see the coil hookups) :) > > thanks > sam > > Jon Elson wrote: > >> Andy Pugh wrote: >> >> >>> Thinking about this some more, I think it is a quadrature LVDT. >>> As we discussed on IRC it is a lot like an LVDT with multiple >>> armatures. The thing is, if you only have that then you can't infer >>> direction. By having two offset read-heads in quadrature you can tell >>> direction. >>> >>> >>> >> Well, a classic LVDT is a non-repeating position measuring device. >> >> The Farrand Inductosyn can be run like this, but the difference is that >> the pattern of exciting windings repeats periodically. >> The Inductosyn has no pole teeth, and the long scale has a continuous >> zig zag of traces on a ceramic or PCB substrate. >> Obviously, the scale has low resistance and inductance, therefore it >> requires a lot of drive current. The pick-up sensor is usually a short >> length of identical zig zags, with the sin and cos sensor 90 degrees out >> of phase relative to the long scale. >> >> The GE and other sensors were made to offer a similar device but get >> around the Farrand patents, which were quite well written and precluded >> any closely similar scheme. Having slots and no coils on the long scale >> was different enough to not infringe on Farrand. These could be made >> with 3 coils, and the variation of magnetic coupling between the teeth >> and the coils changes the amount of excitation that gets to the sense >> coils. I don't know how you do this with only 2 coils, and it probably >> restricts the excitation and sense circuits quite a bit. >> >> Jon >> >> ------------------------------------------------------------------------------ >> Download Intel® Parallel Studio Eval >> Try the new software tools for yourself. Speed compiling, find bugs >> proactively, and fine-tune applications for parallel performance. >> See why Intel Parallel Studio got high marks during beta. >> http://p.sf.net/sfu/intel-sw-dev >> _______________________________________________ >> Emc-users mailing list >> Emc-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/emc-users >> ------------------------------------------------------------------------ >> >> >> No virus found in this incoming message. >> Checked by AVG - www.avg.com >> Version: 8.5.437 / Virus Database: 271.1.1/2804 - Release Date: 04/11/10 >> 06:32:00 >> >> >> > ------------------------------------------------------------------------------ > Download Intel® Parallel Studio Eval > Try the new software tools for yourself. Speed compiling, find bugs > proactively, and fine-tune applications for parallel performance. > See why Intel Parallel Studio got high marks during beta. > http://p.sf.net/sfu/intel-sw-dev > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > > ------------------------------------------------------------------------------ Download Intel® Parallel Studio Eval Try the new software tools for yourself. Speed compiling, find bugs proactively, and fine-tune applications for parallel performance. See why Intel Parallel Studio got high marks during beta. http://p.sf.net/sfu/intel-sw-dev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
