On Monday 12 September 2016 14:44:33 Chris Albertson wrote: > I think the RC filter idea would work OK. Gear teach are after all a > low frequency signal, so a filter made with a cap size for a corner > freq of (say) 100KHz will keep RF out of the line. > I was thinking more in terms of a rail to rail bypass.
> That said the "correct" way to do this is with a pair of > driver/receiver chips. If you use RS422 (that is a differential > signal) you can likely go over a 1/4 mile of trusted pair wire. > > As for wire why not use Cat 6 or better for a machine shop cat-6 > shielded. It is terminated in RJ45 and it's dirt cheap. And has > enough pairs (4) for your use. > > Also I was reading LinuxCNC docs, it said a spindle encoder needs to > be quadrature. You need two sensors for that phase A and B plus a > third for the index. Cat 6 has four pairs so you can use the 4th > for power to the sensors. Thats been the plan from the getgo, and its required for rigid tapping. Only way to fly IMO. > As I said, the simple RC filter like you suggested can work but the > "classic" method for use in a shop filled with high power machines is > to use a differential single as it is immune to common mode noise, > then use twisted pair in a sealed that is grounded on ONE end only, I can switch to shielded cable once I get outside the spindle housing, so if its needed, I will. > On Mon, Sep 12, 2016 at 10:43 AM, Gene Heskett <ghesk...@shentel.net> wrote: > > Greetings all; > > > > I see by the spec sheet that the allegro 667 gear sensor can sink up > > to 25 mills. > > > > But with 3 such sensors on the end of a long cable back to the > > breakout board, probably 7 foot by the time I get it routed, I am > > concerned with the potential for crosstalk noise in spite of putting > > a bypass capacitor on the encoder itself. > > > > This noise would be reduced by a lesser amount of current. So, for > > those of you using this device, what value is the resistor are you > > using for a pullup at the breakout board? > > > > And if using a piece of idc ribbon cable, it seems to make sense to > > put a grounded wire between each of the A|Z|B conductors, making > > that a 7 conductor cable rather than a 5. I have around 90 feet of > > 26 wire ribbon I can split off what I need from. > > > > Good idea? Or off the wall & probably will be plagued by noise if I > > shoot for a 10 milliamp pullup with a 470 ohm pullup, or even 5 > > mills with a 1k pullup. > > > > Time to assemble that motor driver box I believe. Thanks Chris. ' > > > > Cheers, Gene Heskett > > -- > > "There are four boxes to be used in defense of liberty: > > soap, ballot, jury, and ammo. Please use in that order." > > -Ed Howdershelt (Author) > > Genes Web page <http://geneslinuxbox.net:6309/gene> > > > > -------------------------------------------------------------------- > >---------- What NetFlow Analyzer can do for you? Monitors network > > bandwidth and traffic patterns at an interface-level. Reveals which > > users, apps, and protocols are consuming the most bandwidth. > > Provides multi-vendor support for NetFlow, J-Flow, sFlow and other > > flows. Make informed decisions using capacity planning reports. > > http://sdm.link/zohodev2dev > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ What NetFlow Analyzer can do for you? Monitors network bandwidth and traffic patterns at an interface-level. Reveals which users, apps, and protocols are consuming the most bandwidth. Provides multi-vendor support for NetFlow, J-Flow, sFlow and other flows. Make informed decisions using capacity planning reports. http://sdm.link/zohodev2dev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
