Re: emc help

Hello
I think you missed the whole point.
The limiting factor of an encoder usually isnt the electronics but
the light reader that reads the light that show thru the disk.
Think about how dim the light would be when the disk is spinning fast.
Less an less light reaches the reciever with the more lines density
and the faster the disk rotates.
I have seen with a scope the nice square get smaller and smaller as
the speed increased until it was lost in the noise and of course the
machine got an encoder fault.
Hiedenhain scale .001 mm resoulution 30 meter/min ,alignment as close
to perfect as possible.

As i said in a previous message and you can verify the specs.
BEI 100khz max
Dynapar 125khz max
Hiedenhain 300 khz max
Canon laser encoders 500kz-675khz max , up to 230 million count per
rev
Thusly this is why a laser encoder has much more bandwidth,they have
colliminated laser beam

An ls7166 might be able to read 10mhz in the lab but as i said in a
previous message not in an industrial enviroment.

Walk out to a cnc shop with a scope and you will see what i mean.

I would like anybody to find an encoder with a max freq in the mhz.

Regards,
Greg

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Jon Elson <elson@p...> wrote:
>
>
> Ray Henry wrote:
>
> >My last wonder is why would a company like STG build a card and
report
> >that it will read 10MHz if they knew that there were no pulse
coders out
> >there that could come even close to that speed?
> >
>
> Because it comes STRAIGHT off the data sheed for the LS7166 encoder
counter
> chip they use. It can do 10 MHz because it has NO FILTERING
whatsoever
> on the quadrature inputs. At 10 MHz, the encoder signals better be
REALLY
> free of any noise, or there will be an accumulation of missed
counts.
> That's
> why the LS7266 chip added a digital filter on the quadrature inputs.
>
> Jon