[GreenKeys] Arduino Code/Speed Converter

[Jim Haynes]

On Fri, 24 Jan 2020, Gil Smith wrote:

> I did some tests on a 15 (direct to magnets) and was able to get good copy
> down to about a 15 volt loop supply, though that is probably pretty marginal

Was that 15 with a holding magnet selector or a pulling magnet selector?

I've never seen this in print, but Walt Zenner told us that the reason
for the holding magnet selector was so that TWX switchboards could work
with 48V instead of 120V on the cord circuits, thus protecting the
operators who occasionally would come in contact with the bare metal on
the plugs.