RE: STG and Parallel Port

["Erie Patsellis" <signworks-at-mcleodusa.net>]

Les, depending on your inverter, it may already output a signal.
on my Precise controller it outputs 6hz/rev, run through a 55 with a
short time constant and voila! spindle run indication....

erie



-----Original Message-----
From: emc-at-nist.gov [emc-at-nist.gov]On Behalf Of Les Watts
Sent: Wednesday, November 20, 2002 8:42 PM
To: Multiple recipients of list
Subject: Re: STG and Parallel Port



Paul, thanks for the run. I will set to either bridgeporttask/bridgeportio
or minimilltask/minimillio- whichever pair works!

Jon, your idea sounds good to implement spindle sensing. There are
plenty of ways to get the signal to EMC even if it does not have this
function.

So a couple hundred turns of wire on a small alnico magnet near
the collet nut can be the sensor. No need for hum bucking. The 
signal will be some tens of mv, so a quad op amp can perform
absolute value or half wave rectification, filtering, amplification,
and voltage comparison to give a logic high above some spindle
rpm. I use quads for everything since they are the
same price as singles. :^) The magnetic pickup is a rate device,
so signal amplitude will go up with rpm. No need for a frequency 
to voltage conversion. Then a 555 as a one shot with the 
spindle on signal and a couple logic gates can control
amp enable, fault, or part of my external e-stop circuit.

Les

Leslie Watts
L M Watts Furniture
Tiger, Georgia USA
http://www.alltel.net/~leswatts/wattsfurniturewp.html
engineering page:
http://www.alltel.net/~leswatts/shop.html
Surplus cnc for sale:
http://www.alltel.net/~leswatts/forsale.html