[GreenKeys] What the heck is a "Selector Key"?

[Jim Haynes]

If you have that stuff in San Diego then that is probably the stuff
that goes with that box in the Model 19 set in your basement - somewhere
I have it written down what that was called.  I believe it used one
of those rotary 60-type selectors.

The Western Union use in connection with messenger boys records the
signal as Morse on a tape, rather than operating a selector mechanism.
Also it's quite similar to the old manual fire alarm systems, which
also record on a tape.  They use a clever circuit for that stuff with
the wire in a loop through all the stations, and if the wire gets
grounded anywhere it will still work on the portion of wire between
the ground and the central station.

As mentioned, the scheme was quite popular with railroad telephones,
because they are the ultimate party lines - like 60 stations on one
wire, so you want to cut off the ones that you are not intending to
talk to.  Has also been used with Morse telegraph stations where
the operator has other duties and needs a signal better than hearing
the office call letters on the sounder to let him know his attention
is needed.

There is a thing called a Gill selector that is similar in principle
to the W.E. 60-type selector.  Patent on the Gill selector is
906,523 of 1908.  The W.E. selector patent is 1,343,256 of 1920,
but has an ancestor in 1,200,095 of 1916.

www.pat2pdf.org is an easy way to download a patent.


jhhaynes at earthlink dot net