Hi Jon, Would you put the excitation source on the board also? D
BTW - It is my understanding that resolvers will stand insanely high rpm. I've heard figures of 60K rpm. On Feb 9, 2008, at 11:08 AM, Jon Elson wrote: > Stuart Stevenson wrote: >> Gentlemen, >> Jon, I don't know the level of demand for a resolver board. Would >> this be a ppmc card or a separate module? I would like to have the >> option in the ppmc set. If the price isn't too high I would buy five >> to start. > I think it makes more sense to just make a resolver to > quadrature board, maybe with a DC tach emulator, too. It could > still be used with the PPMC, of course. >> There are still quite a few machines in service that have >> resolvers. >> All the early Fadals have resolvers. I am not sure when they went >> to pulse encoders. Both of ours have resolvers. Our newest one was >> purchased in 1998. >> The older Cincinatti 5 axis machines have resolvers. >> I am sure as time passes the resolver demand will continue to >> dwindle unless there is some overriding advantage to using resolvers >> and the use is facilitated. In what application would a resolver be >> the preferred choice? Why? >> I have heard price is the reason people have switched to pulse >> encoders. Unless alzheimer's has prevailed I remember the price of >> pulse encoders is around US $150.00/$200.00. and the price of >> resolvers for our Fadals is US $150.00/$200.00. Doesn't seem to be >> much difference. > Some of this is historical nonsense. The original optical > encoders used light BULBS, and when the bulb went out, you could > have a servo runaway. This gave encoders a bad name. Also, > some of the early LED encoders suffered from degrading of the > LED, and would eventually become unreliable. They also need > good seals to protect the optics from contamination. > > Resolvers can run fine when filled with water or oil, and there > are no active devices in them to wear out. >> Maybe the reason everyone uses digital is there is no good/cheap >> way to get the analog signal into the current controls? > Yes, although the latest AD chip really brings the price down. >> This is definitely beyond my expertise but my perception of the >> comparison between digital and analog is something like this. >> With digital, the signals do not deteriorate until they just >> don't >> work anymore. There is no adjustment necessary (or even possible). >> With analog, as the individual components deteriorate the signals >> need to be adjusted. Sometimes, this gets to be quite frequent and/or >> involved. > Yes, that is about right, although the AD chip, once set up for > the right voltage and frequency, should not need any adjustment. >> Therefore, the initial cost be equal, the maintenance and repair >> of digital is cheaper and easier than analog. > In the old days, with boards covered with dozens of trimpots, > that was absolutely true. >> What about pressure/temperature transducers? Would a resolver >> board also be able to connect to these and allow the use of their >> feedback? Maybe with another pin selection? > Possibly. They often use either strain gauge or LVDT, which is > somewhat related to a resolver. But, I think AD makes chips > more specific for that application. A resolver-digital > converter is expecting a sine/cos relationship, where those > sensors produce a linear relationship between signals and position. > > Jon > > ---------------------------------------------------------------------- > --- > This SF.net email is sponsored by: Microsoft > Defy all challenges. Microsoft(R) Visual Studio 2008. > http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
