Re: [CAD_CAM_EDM_DRO] Re: Quadrature Divider ?

I wonder about these encoders. I cannot find a specification for their
maximum speed. There is a description of how they work on the web site.
They use a capacitive pickup against a wavy pattern on the encoder wheel.
There appears to be about 8 waves per rotation. That means that
they are multiplying the 8 waves by various factors to get all their selectable
resolutions. This technique probably limits their maximum speed. I am
suspicious that they don't specify it anywhere that I can find. It could be
fairly low!

Pete.

----- Original Message -----
From: Mariss Freimanis
To: CAD_CAM_EDM_DRO@yahoogroups.com
Sent: Tuesday, January 06, 2009 2:43 AM
Subject: [CAD_CAM_EDM_DRO] Re: Quadrature Divider ?


Alan,

Your best bet is to go to digikey.com and order yourself up some
AMT-102 encoders. They are $29 in single quantity and the cover every
possible resolution you have in mind from 48 lines per revolution to
2,048, all DIP-switch settable. They are terrific encoders and we have
tried them. Best thing since sliced bread.

Mariss

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "alanrothenbush" <alan@...> wrote:
>
> I got a good deal .. sorta .. on half a dozen servo motors, intended
> for use with some Gecko 320s (already purchased).
>
> The "sorta" part comes from the fact that I must have misread the
> part number; they do not have 250 count encoders, as expected, but
> 2,000 count encoders, meaning that even with my fastest computer,
> they run way too slow.
>
> Now I could just purchase some Gecko G902s but I'm afraid that's not
> really an option for budgetary reasons; this is just for hobby use.
>
> Some of the options I'm considering are
>
> . a poor man's pulse multiplier, kinda like a G902, only without the
> PLL fanciness; maybe a PIC that outputs 8 pulses for each incoming
> step pulse. Easy, but I wonder how important it is that the pulses
> be nicely spaced ...
>
> . a quadrature divider .. maybe a PIC doing a bunch of counting.
>
> (Here's a question .. would a flip-flop wired as a divide-by-two work
> as a simple divider ? And if so, couldn't a guy cascade three of
> them for a divde-by-eight ?)
>
> . one of the USB pulse engine options like the ncPOD or
> SmoothStepper
>
>
> Any thoughts, opinions or circuits gratefully accepted.
>
>
> Alan
>





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