Re: Homebrew STG card

["Matt Shaver" <mshaver-at-erols.com>]

> From: Paul Corner <Paul.Corner-at-tesco.net>
> You asked about including analog inputs -
> How many inputs, resolution, and bufferd or not ?

I don't really know. That must sound strange, but I brought it up since the
STG card has it. The only uses I can think of for this feature would be:

1. Some servo amps output a voltage proportional to motor current, and this
could be useful for a system that tracked tool wear (or some other
application I haven't yet imagined)

2. Some variable frequency drives have an analog output for motor speed. This
might seem to be redundant except that they also do soft starts where the
RPM's ramp up over time.

I don't think either of these ideas requires extreme resolution, perhaps only
eight bits. Within the eight bits it needs to be accurate enough so that
comparative measurements are meaningful. Scaling is another issue yet... I
could very easily live without this feature if it's a lot of trouble. Perhaps
some accommodation could be made for your comparator idea?

> Managed to spend a couple of hours at work, playing around with the general
> layout. It looks as if I can squeeze everything in without going to
multilayer
> or using super fine traces.

Good!

> What sort of data exchange formats can you handle ?
> I suspect a HGPL plot may be the only easy output I can generate - and
GERBER
> exports.

I'll get along fine with either. Corel Draw can import HPGL and I could
probably get a freeware Gerber viewer from somewhere. What does the schematic
look like so far?

Matt