On 2/28/2017 12:17 PM, Ethan Dicks via cctalk wrote:
  It sounds like he is contemplating a battery-powered
tape drive
 emulator that plugs on the outside of the machine for users to use
 without opening their boxes.  It would then be portable to other
 machines.  Sounds like a great idea. 
This year's CocoFEST is open to all TRS-80
models, not just the Coco,
and I noticed that many of the models have a similar cassette port
connector (I think they have variations on the format), and so I thought
of a neat project that might be of interest to all of the participants
of the show.
As you note, picking off 5V from inside, while entirely possible, is far
 from optimal, and a uC is the intended recipient.
Besides, as Tony  
implies, I should know this stuff, but I have indeed managed to
move
along in my efforts for so many years without needing to use a
comparator :-)
--
Jim Brain
brain at 
jbrain.com
www.jbrain.com