[GreenKeys] Manual for Teletype EIA-232 Current Interface

[Justin Scott]

So, I've been following this with some interest since I had to build my own interface so I could hook a modern computer to my Model 33 ASR to dump
some tape images to the TP, I never knew that Teletype created their own interface (or, possibly re-branded someone else's stuff).

This setup looks to be nicely done, possibly opto isolated on both ends, with proper level shifting to address the +12/-12v nature of RS232.

The dip switches, two are marked on the PCB and the others are not - simply put those two are to address whether or not the interface should provide
Data Set Ready and Data Carrier Detect to the device on the RS232 end of things.  The four screw terminals are obviously the loops for the teletype,
but which ones and which polarities would be difficult to discern without documentation or having the circuit in hand to follow the traces back to
their components.

If you plug it in, you should see loop power on both "sides", and should be able to tell polarity with a multimeter, that would be a start, but
knowing which one goes to the teletype's TX/RX pairs would be slightly more difficult.  You could hook it up on the RS232 side, and then send a string
of repeating characters into the converter, you should notice electrical differences on one pair of the screw terminals while this is happening, and
that would be your receive pair for the teletype.

cheers,
j

Sarah Autumn(neverether) wrote:
> Hey all, here are the requested photos. If you are viewing this email on
> greenkeys, and can't see the embedded images, please follow the link here
> to view the album.  http://imgur.com/a/Nq8Ds
> 
> Thank you :)
> 
> [image: Inline image 4][image: Inline image 2][image: Inline image 3][image:
> Inline image 6][image: Inline image 5][image: Inline image 1]
> 
> On Sun, Jul 26, 2015 at 11:43 AM, Robert Laag <rlaag at pacbell.net> wrote:
> 
> > PLEASE SEND A PICTURE TO ME AS WELL...
> >
> >
> >
> >   On Sunday, July 26, 2015 8:35 AM, Sarah Autumn <neverether at gmail.com>
> > wrote:
> >
> >
> > Yep! I'll take some pictures today.
> >
> > On Sun, Jul 26, 2015 at 6:31 AM Mike Douglas <deramp5113 at yahoo.com> wrote:
> >
> > I'd be very interested in seeing pictures, including the inside. Is it
> > actually Teletype branded?
> >
> > Mike
> >
> > > On Jul 25, 2015, at 9:46 PM, Sarah Autumn <neverether at gmail.com> wrote:
> > >
> > > Hey all,
> > >
> > > Does anyone happen to have a manual for the EIA-232 current interface
> > made by Teletype? I've found manuals for other brands, but they don't seem
> > applicable to this one.
> > >
> > > This interface doesn't seem to have a model number on it. It's a black,
> > rectangular metal box, about 8" long x 5" wide by 3" deep (estimate). It's
> > got 4 terminals on one end, and a DB-25 connector on the other.
> > >
> > > Thanks!
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