Re: How to get a signal to controll spindle speed?

[John Sheahan <jrsheahan-at-optushome.com.au>]

Hi Ray
most obvious solution would be a serial adc like maxim's
max1232. needs 3 wires out the parallel port.

hovever this is proving that its possible to extend 
ancient tech like the parallel port to ridiculous extents.

Is there any obvious reason why USB could not be used 
instead? much more flexible.

A more reasonable solution would be to stuff a small 
opto interruptor or hall effect onto the shaft, connect that 
to a single chip PIC,  and get serial speed messages from that. 
Serial could then go into  standard serial ports, or usb serial, 
or a multiport serial card 
for the wealthy ones. usb devices on cypress stuff is pretty 
easy to add.  
I can post code and circuits, even a couple of proto boards and
programmers  for the PIC if people are interested.
 
What kind of feedback comes from the laser as to power?
And I thought the thread started with a PWM request. where did analog 
come in? must have missed something key. 

John


On Sat, May 18, 2002 at 09:31:55AM -0400, Ray Henry wrote:
> 
> 
> List
> 
> I've got to say that I find this thread fascinating.  Nice creative solutions 
> to getting some kind of analog signal out of a parport.  How would we close 
> the loop by getting spindle or laser intensity back into the emc without 
> using a full servo board solution?
> 
> Ray
> 
> On Saturday 18 May 2002 06:25, you wrote:
> > On Friday 17 May 2002 15:36, you wrote:
> > > Hi list,
> > > Can anyone tell me how typically a mill with
> > > controllable spindle speed out the emc is being set
> > > up? I want somehow a possibility to controll
> > > laserpower by the emc software. I think I could use
> > > the "spindle speed" command for this purpose.
> >
> > you could use a simple  555 timer with an electronic variable resistor
> > these usually have up/down logic inputs which 'move' the wiper tap
> > and are very cheap & cheerful ,