• Matt Blaze@federate.socialOP
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    8 days ago

    NYC’s IRT subway, opened in 1904, is powered by a 600 volt DC third rail running alongside the tracks. Power is fed to the system via a number of substations throughout the city, where high voltage AC is converted to the lower voltage DC used by trains.

    Until recently, this was done with electromechanical rotary converters (essentially a combination AC motor and DC generator). They are now supplanted by solid state rectifiers, but a few of the original rotary converters remain operational.

  • Karl Auerbach@sfba.social
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    8 days ago

    @mattblaze@federate.social I hadn’t had my morning coffee and my first thought when I saw this photo (of the rotary converter) was “oh, that is a top view of a Curta calculator.” (I used to be pretty good on a Curta.)

      • Chris Samuel@mastodon.acm.org
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        8 days ago

        @mattblaze@federate.social @karlauerbach@sfba.social continuing the theme of misunderstanding what you’re seeing, I saw that and was thought it was a clockwork camera lens for a second (not that I think there is such a thing, but my brain isn’t that quick today).