On Friday 24 January 2020 07:34:27 Les Newell wrote: > > Not all, the 7i90 being a rather glaring exception, it's cheap for > > it capabilities but needs another $135 in 7i42TA's to protect it. I > > suspect that any of the Mesa cards that output via 50 pin scsi > > connectors have similar restrictions. > > Yes, the FPGA boards do need buffering but any logic level I/O device > needs buffering to control relays etc. You also need to protect > inputs. If you want to roll your own I have a design for a Mesa > compatible I/O buffer board that has opto isolated inputs and 100mA > Darlington outputs that can be configured to drive high side or low > side. I/Os are configurable at build time in groups of 8. Each group > can be input or output, high side or low side. All thru hole > components for ease of hand soldering. I originally designed it as a > practice project when transitioning to using Kicad and have used it on > a couple of machines now. I've been meaning to release it as open > source hardware but never found the round tuits. If anyone is > interested I'll knock up some docs and stick it on the wiki page or > something. > > Les
Opto stuff, with their speed limits, are much more trouble than they're worth, I've cut many of them out of bobs. A limiting resistor and a schotkey diode to each rail s/b be input protection limit enough. And yes, I'd be interested in something that I could run thru pcb2gcode and make myself, and I suspect I am not alone. I've even done the drill holes at only 40 thou into the board from each side and made them meet in the middle of the board. And I've got lots of board. The 7i90HD is a good start on a do anything board, but it sure needs protection, its very easily damaged by stray noise. > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
