[GreenKeys] Big Bird Loop Interface

[gil smith]

Hey Big Bird group:

Jack, George, and I have been mulling over a little circuit board to add to
the dovetrons for directly driving a current loop from the dovetron 232
output, and sensing loop data for sending to the dovetron tx section.  Jack
already has a tempest dovetron he has been looking at.  Unless you are
planning to drive a 232 printer, or already have a 232-to-loop converter,
we presume you will want some way to drive your TTY machines.  

So how about a little poll?  I'd like some feedback as to what features you
folks might like in such a board:

- do you care at all?  Or, do you already have a 232-to-loop adapter to use?

- do you want to drive a high-voltage loop (120-150V for M14/15/19/28...),
or a low-voltage loop (30-45V for M32...)?

- how many tty loop jacks should be available?

- would you mind drilling holes in your dovetron to add a board inside?

- would you rather mount it externally in a box and connect to the dovetron
BNC connectors?

- would you rather mount it externally in a box but connect to a DB-9
connector that you add to the dovetron?

- do you plan to use half-duplex (single-loop rx/tx), or full-duplex (two
loops for rx and tx)? 

- would you want to add an optional chip or two for doing automatic speed
conversions and/or baudot/ascii conversions?  Then you would no longer need
to worry about machine gears -- demod to any speed machine.  I have already
done most of this code.  This can also automaically insert CR CR LF LTRS at
72 chars (or N chars), or add an LF after a CR that has none...  Tell me
what you want.


This interface will be similar to the TTY232 board I did before -- a fully
opto-isolated 232 to loop interface.  But, based on your feature feedback,
would likely be simpler, smaller and would have a soldermask and silk
screen this time.  I think I will offer bare-board only, or full parts kit,
to make it easier for folks to get started.

thanks,

gil



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