In a message dated 98-01-16 20:24:07 EST, you write:

<<
 This is for anyone contemplating using opto couplers or similar devices in
 projects.

     "USE ONLY AS A LAST RESORT!"

 Why?  They are SLOOOOOOOOOOW!

 So before you design them into a project, go to SIEMENS web site
 <http://www.siemens.com>, find the opto app notes section and get app notes
 1, 2, 4 and 5 as a minimum. They are in .PDF format and although small,
 ther is enough info there to put you on the right track.

 Good luck with your projects,
 Bill >>


They're not all so slow.  The NEC PS9601 has a propagation delay of 50ns.  You
can commonly find them in the 1-8 microsecond range.

Dave Duley