Re: Interface for CNCPro, etc.

A couple of quick comments:

1. Please use a terminal strip connector (screw terminal block) that will plug into a mating terminal strip on the board so that
you do not have to disconnect individual wires if you need to remove the board or computer.

2. If you are going to have meaning full opto-isolation, you need two independent supplies for the opto board, one using the
computer power side, one using the load power side. I have seen several examples were the load side was powered from the
PC.... I assume that you already know that.

3. I usually connect direct and make sure the computer and the load is powered from one common point and are well grounded
together. Further, I try to keep wires reasonably short and I do not roll up excess wires into a coil. I fold it together and
tape it to avoid the pickup coil effect.
Bertho Boman
==========================
From: "Harrison, Doug" <dharrison@...>

> -----> snip
> I have a proposal, for which I need your opinions and feedback - maybe even
> a little technical expertise.
>
> Suppose I design a card that will fit in one ISA or PCI slot that has
> optoisolation, 5V isolated supply for outputs and a screw terminal strip
> that sticks out the back for direct connection to amps, switches and aux
> I/O. No interface cards to make, no pullup resisters to find a home for, no
> breakout boards to buy, no 25 pin DIN connectors or cut-to-length serial
> cables to fiddle with. Just connect the amps, switches and I/O to the back
> of the PC and go.
>
> I am working on a prototype of this board and plan to build at least a few
> of them for my own applications. A little profit from the sale of such
> cards would be nice, though that is not my goal, nor will it influence my
> decision to do the design. At the very least, the plans could be released
> to public domain.
>
> Questions:
> 1. Do you see enough demand for this kind of board to justify having 50-100
> PCB's etched?
>
> 2. What functions or features would you add or subtract?
>
> 3. Would you prefer a separate (not in the computer) board fed by a 25 pin
> cable? This would require an additional cable from the PC power supply to
> feed the 5V isolator.
>
> 4. I have selected a few candidates for the optocouplers and a shottky
> driver to feed them. However, component selection is not my area of
> expertise (I'm not sure what is). Can somebody recommend components that
> will give a good clean pulse at 100khz? Perhaps a good representative
> circuit?
>
> I eagerly await your humble opinions.
> Doug Harrison