Re: mounting encoder with pulley

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Alan Marconett <KM6VV@a...>
wrote:

> Hi Caudlet,
>
> You might be right! But as I seem to remember using two F/Fs

driven by

> exclusive OR gates to decode quadrature signals, it occurs to me

that

> several stages of counters could be cascaded, and the "slower"

stages

> would count the same, just slower. A state machine, if you will.

So a

> long counter could be set up in a PAL or PLA, and operated with a

state

> machine. The count should probably be divided by a binary power.

A

> divide by 4 seems about right for me.
>
> Alan KM6VV
>
>

Gee, PAL's and PLA's and all that stuff! I would just grab a CD4015B
Dual four bit shift register (about 50 cents) and pick a divide by 2,
4, 8, or 16 output. The encoder just puts out two 90 deg phase
shifted square waves and turning it into quadrature is the work of
internal circuits. If your line count was 1000, then each channel
puts out 1000 pulses. If you divided each by 4 then you end up with
250 each and back to 1000 in quadrature. Use the divide by 8 and you
are down to 500 in quadrature. As long as you kept the 90 phase shift
it should work out. One chip. You might have to use an LS type chip
if the RPM of the motor was very high.

Of course you could use a PIC and spend 4.00 bucks and hours writing
a program to do the same thing and it would be really neat. I am at
the stage in my design career where 'really neat' has been replaced
with 'do it fast and cheap' so I have more time to make chips.