On Friday 24 January 2020 12:14:01 Les Newell wrote: > Hi Gene, > > > 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. > > I have to disagree. Unless you need high speed, such as for encoders, > optos are very worthwhile. Their slow speed helps mask out any short > duration noise on the line. The isolation is also good for reducing > noise. > > > And yes, I'd be interested in something that I could run thru > > pcb2gcode and make myself, and I suspect I am not alone. > > The layout is pretty tight for mechanical etching. If I remember > correctly some track gaps are only 0.006". Making the board very > configurable had the down side of also making it pretty tight in > places. It's a 100mm x 100mm board and some Chinese PCB manufacturers > are offering crazy low prices to build this size board. I used to make > my own boards but these days it is so cheap to get them made it is not > worth the effort. I've found the Chinese made boards to be very good > quality. I just checked on pcbshopper.com and you can get 5 delivered > to your door for a total of $8.33 in 23 days or if you are in more of > a hurry how about $13.38 in 16 days? > Humm pcbshopper.com, got a project "code" I can order and a doc & BOM I can DL? Currently using a 5i25 with a 7i76D on p3 on two of my mills but any sneeze of the power crashes the sserial link requiring a full power down, count to ten reboot. All supplies must die totally to recover.
And I'd like to see if the 7i90HD thru the parport could run it more dependably. So I have the cost of three 7i42TA's as impetus to look at building your board instead. > > 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. > > I've used quite a few of the Mesa FPGA boards and I've only ever > killed one - that was by feeding 24V back down one of the outputs. > Maybe you should consider using optos ;-) I wound up fixing my admittedly hasty original layout/hookup, which was giving me switching noise from the stepper drivers at around 40 volts p-p and 3ns rise times. With everything on a single point ground bolt, the noise fell into a black hole and is now under 100mv. But I have also fitted 3 7i42TA's because that also gave me std screw terminals to wire it up with. No more jumpers jumping off an unmarked pin in the 50 pinners just cause I opened the garage door. Best. Fix. Ever. And I'm still running on a 7i90 with 2 blown stepgens. But with 8 to choose from, the hal file reassignments were trivial, and has been working for 2 years now. Switched from an rpi3 which was dragging its tongue on the floor to an rpi4 last fall, sweet. No latency overruns, none! And I still have about 30 spare outputs/inputs if I ever get a tool turret carriage. > Les > Thanks Les. 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
