Re: the early teletype

On 2024-11-15 00:11, Charlie Gibbs wrote:

On 2024-11-14, Sn!pe <snipeco.2@gmail.com> wrote:
 

Lawrence D'Oliveiro <ldo@nz.invalid> wrote:
>

On Thu, 14 Nov 2024 22:19:48 +0000, Sn!pe wrote:
>

Lawrence D'Oliveiro <ldo@nz.invalid> wrote:
>

On Thu, 14 Nov 2024 18:45:48 GMT, Charlie Gibbs wrote:
>

Original Teletype machines ran at 45.45 baud.

>
I remember labels on Creed machines saying "50Bd".

>
I had a Creed 7B 60 years ago, I used it for RTTY.  It had two
governers, one for 45.45 Bd, the other for 50Bd.  They had white
strobe marks on the circumference to set the speed accurately.

>
Hmmm ... presumably the strobe marks were for use with a fluorescent
light ... driven from AC mains frequency? Did they have different marks
for 50Hz versus 60Hz mains?
>
No, that wouldn't work, you would need entirely different gearing for the
strobe wheel ...

>
IIRC 50Bd was the US standard, most common in the rest of the world
was 45.45Bd  There was no gearing involved, the governor was attached
directly to the motor spindle and the strobe timing marks were on the
governors themselves.  I think (I'm not sure) that there were a
different number of strobe marks on either governor.
>
I speak from personal experience but it was 60 years ago when I was
a teenager and memory is a tricky thing.

 To further muddy the waters, 45.45 baud was just an average.
Start and data pulses were 22 milliseconds long, while the
stop pulse was 31 milliseconds.  (I guess the mechanism wasn't
quite fast enough to process the received bits...)
 Damn, the things one remembers...

They were in use at my time, somewhere, but I never saw one. Faxes were what they used.
Did teletypes use phone lines, with an audio coupler? Or dedicated lines?
--
Cheers, Carlos.