Re: [CAD_CAM_EDM_DRO] Re: Controlling VFDs from your PC?

audiomaker2000 wrote:

> Thanks guys.
>
> That makes me ask....
>
> How do you produce an analog signal of varying voltage from one of
> your computer's ports? I don't know much about this, but from what
> I've read, most pins produce either a "high" or "low" condition which
> I can see triggering a relay, but not a variable "pot".
> I suppose this is normally taken care of by the complex electronics
> of a CNC machine, but I am retrofitting with a system that appears to
> only produce step and direction signals.
> So how do you turn your computer into a "dimmer" instead of
> a "switch"?

You have to use a DAC - Digital to Analog Converter. For spindle
speed, an 8-bit DAC (256 different output voltages) might be enough.
You can buy these fairly cheaply from some of the computer hobby
outfits, and also from outfits specializing in computer interfacing gear.
Computer Boards has a catalog of all sorts of gear of this sort.

Jon