Re: Need help with parallel port input design

Lloyd:

I actually use the same board on my other port. I bought an output
only 8 relay board for a second printer port (for MACH2) and would
like to add input functions to it. I figured someone must have the
circuit drawn up for opto's already.

Regards,
Jeff



--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Lloyd Leung" <lloyd@l...>
wrote:

> Jeff,
>
> I think an opto-isolator is overkill. I would suggest using a 7404

or 4069

> hex inverter, to accomplish the same thing. Both are very cheap.

Download

> the PDF (google, "7404 pdf" or "4069 pdf") and see what pins are

what.

> You'll figure it out.
>
> Use a 7805 voltage regulator to get the power from the 12V source

down to 5V

> as well. And to clean up the power, place a 10uF cap across the

output and

> ground after the 7805.
>
> A resistor network of 10k ohm will help pull up the current to 5V

as well.

>
> Depending on how quickly you want this board, I would recommend Dean
> Coullard's break out board. It's well made and clean, and simple.
> http://members.shaw.ca/axxus/db1v20.htm . I asked him last week,

he was out

> of stock, but will be getting some in soon.
>
>
> I bought one, and am very happy with it. It made things a lot

easier to

> wire up.
>
>
> Cheers.
> Lloyd,
> Toronto
>
>
>
> -----Original Message-----
> From: washcomp [mailto:jeff@w...]
> Sent: September 15, 2003 4:50 PM
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: Need help with parallel port input design
>
> I'd like to provide opto-isolation to the 5(?) input pins on a
> parallel port used to monitor limit switches. I understand that

I'll

> also have to provide some resistors? What's the easiest way to do
> this? I looked at the Digikey catalog and they offer about 4

million

> opto-isolators of all types, but I'm kinda clueless about which to
> use or an actual circuit to make use of the right one. Any help
> would be appreciated. I've bought an 8 port parallel relay board

and

> figure I can retrofit this to the input pins (they are currently

not

> connected on the relay board, but it has a 12v DC supply built on).
>
> Thanks and regards,
> Jeff