Re: mouse encoder

At 01:12 22/08/2001 +0000, you wrote:

>Simply excellent, Tony.
>Bravo.
>This is indeed *exactly* what I was thinking.
>Did your parts come out of a mouse?

No - this is a mouse-free design

>Also, a word on the slots.
>In thinking this over, it occurred to me that one could just as easily
>(if not more easily) simply drill holes in the disc.
>Upon looking at it, it would appear that they put slots in
>only to make it easier to account for not-so-perfect alignment.

That is part of the reason - the other part (which is important for a
quadrature encoder like in the mouse) is that a slot gives a better defined
mark-space ratio to the generated signal.

>If one were to calculate the width of the slot, pick a suitably close
>drill diameter, and drill the holes with a like distance between the holes,
>wouldn't this do the same thing, and be much easier and quicker to make?
>(in other words .031 holes, .062 apart)

This would work fine for a simple sensor like the one in my RPM meter, but
I wouldn't go that way if I was building a sensor that woud generate a
quadrature output.

>I'm thinking that with a 200 step per rev motor, you simply plot the bolt
>hole circle
>for the correct size disc and hole, and start drilling away.
>This seems much simpler and quicker.

If you have the technology to divide the circle (dividing head, rotary
table, CNC mill...), cutting slots vs drilling holes is not that much more
difficult.

Regards,
Tony