[GreenKeys] Teletype (telephone) Local Loops

[ad7i]

Hi Roy --

I can't thank you enough for recommending the AT&T Green Book.  Amazing
that I was a Bell Head for all of my professional career and never knew
about that book.  I would have loved to have had a copy of that book when I
was 10 years old.  I was a wires and batteries kid, and was very interested
in telephones and clickity-clack telegraph systems at a young age.  I don't
have the physical book in hand yet, but I've enjoyed skimming the PDF that
Jerry Murphy referenced.

When I started at Bell Labs I was working on computer design (really system
design, making a mini computer from an 8086 and a slew of Z80s).
Everything was forward looking, not much interest in the past or history.
But I would occasionally spend time in the records office in the Holmdel
basement looking up and ordering BSPs from long ago detailing info about
telegraph systems and such.  Of course I foolishly didn't keep any of the
copies I pulled after reading them.   I'm sure I could have ordered a copy
of the Green Book then if I had know about it.   The Green Book provides so
much great info.

Thank you so much!

73, Paul, ad7i




On Mon, May 25, 2020 at 12:15 PM Roy Morgan <k1lky68 at gmail.com> wrote:

> Paul,
>
> Especially considering your experience with *real* telephone and teletype
> circuits, may I recommend:
>
> “The Green Book”
> Tu Wit:
> Principles of Electricity
>    applied to
> Telephone and Telegraph Work
>
> The copy I have here is entitled on the tile page:
>
> A Training Course Text
> Prepared for Employees of the
> Long Lines Department
> AMERICAN TELEPHONE AND TELEGRAPH COMPANY
> November 1938
> (Reprinted with corrections, January, 1941)
>
> No teletype library should be without one.
> There we’re a number of editions, the later ones omitted some material
> from the earlier ones I think.
>
> I find one on Amazon ("1941 edition" - could be the 1941 reprint) but
> UNFORTUNATELY, the price is $68.00 !!!  The good news is that there is one
> other one offered for less that $10.  Better scoff it up quick!!
>
> I would not be surprised to find it in  PDF form in one of the very deep
> collections of technical books online.  Can anyone post a link to that
> somewhere?
>
> I, too will be grateful for the experience of others about this topic.  I
> have little experience with local loops, but I do have a couple  of polar
> relays and a Model 28 loop supply (here), and some M-15 equipment (in
> distant storage) that will eventually get assembled into a working setup.
>
> Roy
>
>
> > On May 25, 2020, at 11:39 AM, ad7i <ad7i at ad7i.net> wrote:
> >
> > Sorry for the long-winded backgrounding before posing my question…
> >
> > I was fortunate to start my career with "the phone company" when I was
> 16 in a small central office at an independent telephone company in
> Washington State. ...
> >
> > ... my question ... has to do with DC teletype loops (up to 3 or 4 miles
> in length) over dry* pairs leased from the telephone company.   In the case
> of long DC loops for TTY service I assume that the current limiting was
> done via a large wattage resistor located in the same building as the
> voltage source (and not at the customers location).  Is that correct or
> usually correct?
> ...
> > I'd be grateful for whatever knowledge members have to share on the
> topic of DC signaling over telco lease dry pairs.
>
> Roy Morgan
> K1LKY since 1958
> k1lky68 at gmail.com
>
>
>
>
>
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