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

["Patrick Riedlinger" <patr-at-precidesign.com>]

Jacob:

Forget my original thoughts on a circuit. I found something that should be
easy to implement:

Linear Technologies has a Dual 6-Bit PWM DAC. It's Model # is LTC1426

I found this on digi-key. It should do what you want with EMC and the Laser.

Pat Riedlinger


----- Original Message -----
From: "Patrick Riedlinger" <patr-at-precidesign.com>
To: "Multiple recipients of list" <emc-at-nist.gov>
Sent: Friday, May 17, 2002 1:46 PM
Subject: Re: How to get a signal to controll spindle speed?


>
> Jacob:
>
> I am going to stick my neck, out....because I am a Newbie too.
>
> Ray, please step in if I get this wrong.
>
> Ok--EMC has two pins that control Spindle Forward and reverse. They are
> mutually exclusive--that is, when one is on, the other is off. So, it
should
> be easy for you to turn the laser on/off.
>
> However, the spindle increase/decrease pins just output a pulse (of
duration
> unknown to me). Everytime you push the Spindle Increase or Decrease on the
> EMC control panel, it puts a pulse on these respective pins.
>
> BTW, the pins are defined in the emc.ini file, under Aux output, using the
> Bridgeport IO definition.
>
> So it's going to be really hard to PWM your laser with the Inc/Dec
signals,
> since they only put out a (single) pulse every time it is actuated.
>
> I suggest you use some kind of counter (SN54HC4060) with an oscillator you
> control with the EMC pins to produce a up/down digital signal you can
input
> into some DAC to produce a voltage for a VCO
>
> In order:
>
> EMC to Logic
> Logic to Counter
> Counter to DAC
> Dac to VCO
> VCO to Laser
>
> This is off the cuff, so there are many better ways to do this, I'm sure.
> Maybe some other suggestions from the friendly folks in the EMC newsgroup?
I
> am not an Electrical engineer, and my experience is from years ago. I bet
> there is some "canned" IC chip that will do many of the functions that you
> need, nowadays.
>
> Anyway, I will need to be making a similiar circuit to control the spindle
> on my (cheapie) milling machine. I will also need to PWM the spindle,
since
> I am planning to use a triggerable triac type of circuit. I would be
> interested in collaborating with you or other EMC users to figure this one
> out.
>
>
> Pat Riedlinger
>
>
>
>
>
> Ray, if I screw this
> ----- Original Message -----
> From: "Jacob Kranendonk" <j_kranendonk-at-yahoo.com>
> To: "Multiple recipients of list" <emc-at-nist.gov>
> Sent: Friday, May 17, 2002 8:36 AM
> Subject: How to get a signal to controll spindle speed?
>
>
> >
> > 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. But how
> > do I get a signal for this, out of the emc? Does this
> > take extra hardware (like a digital/analog converter
> > or something), or is there a way to get a digital
> > signal to. All I need as a final signal to the laser
> > is a PWM (Puls With Modulated) TTL signal at 5KHZ.
> > Does anyone have a sugestion how I can achieve this,
> > perhaps with the help of some simple IC? Many thanks
> > in advance, Jacob
> >
> >
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