[GreenKeys] Hmmm, why did they do it that way?

[Harold Hallikainen]

On Fri, November 15, 2024 9:27 pm, Jim Haynes wrote:
> What you would like to buy from Teletype is a machine all set up and
> ready to install.  So it could come from the factory configured with
> some connection of the selector coils and with or without a line relay
> block in the LESU and all your installation could be done from the
> back of cabinet terminal strips.  Of course as time went on the number
> of possibilities increased so it was harder to make one standard universal
> set for all applications.

The number of options in these machines is astounding. The model 15s I had
in high school had a fat wiring harness with wires going everywhere and a
polar relay in back. Since I run the machines half duplex (keyboard in
series with selector magnet), there's just a signal pair (60 mA) and AC
power going into the printer. I think the polar relay or whatever line
interface equipment could to in a separate line interface box that might
be a polar relay, a modem, or who knows what. But, the interface to the
machine is 2 wires with 60 mA. 60 mA instead of 20 since every machine
will work at 60 mA. But... I didn't design it.

Harold
https://w6iwi.org



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