On Jun 30, 2009, at 3:26 PM, Haberler Michael wrote: > > Am 30.06.2009 um 17:09 schrieb Andy Pugh: > >> 2009/6/30 Haberler Michael <mai...@mah.priv.at>: >> >>> The code rings are printed on plain paper with an inkjet printer, >>> and >>> laminated into a plastic pouch >> >> Interesting. When I tried a similar approach using clear tape I found >> that the reflectivity of the tape in the frequency range of the >> detectors was so high that the underlying colour was irrelevant. > > I didnt try different colours but tried b/w on paper versus black > stripes on a transparent slide, so the reflection would come from the > aluminum pulley. The latter gave somewhat higher voltage swings on the > coupler's collector, but the glue used to attach the ring would > deteriorate things again (and dissolve the ink if glued onto the > pulley without laminating), so I settled for the paper variant. Laser > printers do give worse results than inkjet. The pouches came with the > laminator. > > I mounted the sensors quite close so they'd "focus" on the paper and > not the reflective surface (and due to lack of space :-). Angular > displacement turned out to be fairly uncritical. > >> >> Is there any sign of interference from your VFD on the sensor pulses? >> I am finding that a bit of a problem. > > no, actually not. In fact the cable is unshielded but I'm going to > change that in the final setup. > > > -Michael > > btw - there are two flavours of CNY70 in the wild, and some have > collector and emitter reversed - make sure to identify the > manufacturer and get the proper data sheet. > Since you have an aluminum pulley you could anodize it then etch the lines on it much in the same manner you would etch a circuit board. IIRC HCl i.e hydrochloric acid works well if your resist will take it. I used to label aluminum panels by a deep etch of the letters then fill with colored epoxies. :-) HTH
Dave > > > ---------------------------------------------------------------------- > -------- > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
