Forgot to include a link. You can buy the bare sensor but also you can buy them on PCBs with connectors attached and ready to go. amazon.com/Measuring-Optocoupler-Interrupter <https://www.amazon.com/Measuring-Optocoupler-Interrupter-Detection-Arduino%EF%BC%885pcs%EF%BC%89/dp/B08977QFK5/ref=sr_1_17?keywords=c+optical+sensor&qid=1648405019&sr=8-17>
Best to use a thin aluminum plate to make the interrupter disk. Make the slots 50% duty cycle, You need three sensors for quadrature with index. The above sensor should directly interface to Measa or a parallel port or some microcontroler. On Sun, Mar 27, 2022 at 10:02 AM Chris Albertson <albertson.ch...@gmail.com> wrote: > THis goes to 10K RPM? that is 167 revolutions per second. 400 slots > means 70 KHz signal. > > Can you design an inductive sensor that does 70KHz but is also sensitive > enough for near zero RPM? Optical sensors can work up to 1MHz with no > problem as they don't have any inductanve. You can buy a "C" space > sensor for a few dollars > > In either case, optical of inductive, you want a 50% "slot" where there is > as much metal left as cut away Then the "edges" of the square wave are the > same in either direction. The 50% duty cycle in effect doubles the > sensor resolution. > > Why? Think about the signal when the direction changes. You have two > sensors in quadrature and lets say one is being blocked and one is not, I > think you want the turnaround to take as long for each sensor. > > > On Sun, Mar 27, 2022 at 2:22 AM Andy Pugh <bodge...@gmail.com> wrote: > >> >> >> > On 27 Mar 2022, at 08:09, andrew beck <andrewbeck0...@gmail.com> wrote: >> > >> > And is bigger dia better for higher resolution? >> >> Probably not, as it will perhaps have more scope to oscillate at 10,000 >> rpm. >> >> Don’t neglect the purely mechanical design of this fast-spinning part. >> >> Have you considered optical sensors rather than inductive? >> >> What will be counting the pulses? >> >> LinuxCNC can lathe-thread with one sensor. >> But rigid-tapping is different as it needs to accurately detect the >> reversal point. So you need three channels for index and full quadrature. >> >> Work out what error you can accept in the reversal point detection (as a >> fraction of thread pitch) and you can get a feel for how many slots you >> need. >> >> >> >> >> _______________________________________________ >> Emc-users mailing list >> Emc-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/emc-users >> > > > -- > > Chris Albertson > Redondo Beach, California > -- Chris Albertson Redondo Beach, California _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
