Re: [CAD_CAM_EDM_DRO] Re: not working!

In a message dated 8/4/00 12:24:01 AM Central Daylight Time,
jmelson@... writes:

<< If the drivers are opto-coupled, then you may need an external 5 V supply
to supply the positive current for the opto couplers (or you can tie into the
+5 V from a disk drive power connector). If you use an external 5 V supply,
the - terminal of the supply should go back to the ground on the parallel
port. >>

AND, some (older?) PC's will not put-out quite enough current to "light up"
Opto-Isolator LED inputs! A bit of a hassle, but I'd counsel to use such as
a ULN-2003 to enable "sinking" more than a few mA, such as is necessary to
"fire" an opto-isolator!