[GreenKeys] Of current loops and voltages.. (M15 20mA / 60mA)

[drlegendre .]

Gents,

As ever, thanks so much for all of your input.. With all the willing
helpers, the info flows quickly.. ;-)

For now, suffice to say I've got the whole 20mA / 60mA and 120V / 24V thing
nailed - as pertains to both early (M14, M15, etc) and later (M33, etc).
We're all good, far as I can tell.

But there are still a couple of questions: Were machines like the M15
normally wired in a "local echo" config? I mean to say, was it SOP to copy
the output of the keyboard to the typing unit as its sent down the line -
or was the sending operator normally typing 'blind'?

This would obviously involve placing the KB and TU in series with the
circuit, and no such connection is shown in the doc(s) I'm using. I did see
a doc that showed what looks like a jumper between one KB and one TU pin
each.. is this is the local echo connection? It seems difficult to type
when there's no feedback on the "screen".

Other question - how is the Send / Rec / Break device used? Break seems
obvious - you press down on the 'small' switch paddle, which open-circuits
the KB line. If the KB were in series with a selector coil, it would cause
the coil to let go and the machine to start printing continuous NULLs. It's
the same situation as with old-school telegraph - you open aka space
("BREAK") the line to interrupt the other party to get their attention.
This is clear..

But how is the 'large' switch paddle used? How does it control Send & Rec?
I can't seem to make it do anything..



On Tue, Sep 15, 2015 at 1:38 PM, Chris Elmquist <chrise at pobox.com> wrote:

> On Tuesday (09/15/2015 at 04:16PM +0000), paul0926 at comcast.net wrote:
> >    For me this list is fine. It works like every email list in every
> >    company I work for and with. It is expected that a person does a reply
> >    to all unless they specifically intent to cut people out of the
> >    conversation.
>
> Boy, yes.  Agreed.  Reply only to the original poster.  Reply-All to
> the group.
>
> Chris NØJCF
>
> >      ------ Original Message ------
> >      From: Jim Walls
> >      To: Greenkeys
> >      Sent: September 15, 2015 at 10:05 AM
> >      Subject: Re: [GreenKeys] Of current loops and voltages.. (M15 20mA /
> >      60mA)
> >
> >    Bill drlegendre at ... wrote (in part):
> >
> >    > A couple other members wrote me (off list, not sure why)
> >
> >
> >
> >    The why is because this list is setup so that replies go to the
> >    original poster and not back to the list.  In my opinion, this is a
> >    really poor way to set up a mailing list for exactly the reason you
> >    saw.  Lots of people reply giving the same information (hopefully)
> >    rather than the first person who responds is seen by all and everyone
> >    realizes that there is no need to reply - again.
> >
> >
> >
> >    Jim - K6CCC
>
> --
> Chris Elmquist
>
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