Re: [CAD_CAM_EDM_DRO] Re: Litton shaft encoder - info?

grantfair2001 wrote:

>I tried 5 volts to supply the encoder. I found 250 PPR from both of
>the two output wires.
>
>There ia only one track on the optically reproduced disc. (there is
>also a track with one index mark but this does not appear to be read).
>There are 4 leds, (infra-red so not visible). Presumably each pair
>includes a light source, and a led to read the disk track. There is a
>house numbered 14 pin chip on the encoder PCB.
>
>Is it possible to get quadrature output from one encoder track only?
>
>

Absolutely, and every encoder I've ever looked at uses only one track on the
wheel or scale. The two sensors have gratings of the same pitch as the
wheel,
but they are installed with an offset of 90 degrees, relative to the
pitch of the
wheel. This gives the 90 degree phase relationship between the two outputs
that are the definition of the quadrature scheme.

The reason for this is if there were two tracks on the wheel, making sure
they were perfectly concentric would be a problem. And, if they were not
concentric, the phase relationship would vary as you turn the encoder, which
is one of the possible error sources in encoders.

Jon