[GreenKeys] Model 15 Selectors

[Joe Duszyński]

The Western Union selector magnets are 1.4 Ohms on their TWX machines
I have the original coils from mine but the part number is a WU number not
a Teletype number.


On Mon, Jan 3, 2022 at 7:38 PM Jim Haynes <jhhaynes at earthlink.net> wrote:

>
> I have seen a military machine with pulling magnet selector and a decal
> on the copy holder saying the magnet coils could be wired in series or
> parallel for 20 or 60 ma operation.  Issue 6 of the Model 15 parts book
> shows only 177M magnet coil, 105 ohms so I don't know whatever happened
> with the magnets used in the Signal Corps machine.
>
> There is mention in the Teletypewriters for the Deaf book of Model 15s
> with low-voltage selector coils of 1.4 ohms resistance, operating on
> 600ma.
>
> The original purpose of the holding magnet selector, according to Walt
> Zenner who invented it, was to allow operation with a loop voltage of
> 48 volts.  The reason was to protect TWX switchboard operators who might
> accidentally contact the switchboard plugs where 130 volts could be
> lethal.
>
>         ---
>
>         "Ya can argue all ya wanna, but it's dif'rent than it was."
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