General Electric 3T18SOL2 Astronomic Time Switch  
Written by AnubisTTP on 2012-09-08  


Back in the hallowed days of our transistor-anemic past, turning light bulbs on and off at preset times was a seriously complicated task - so much so that when the City of New York was hard-up for a way to control its streetlights automatically, they made the dubious decision to mount metal-clad Telechron clocks to every street corner. These devices, manufactured by General Electric, were encased in a heavy vandal-resistant cast case and have a complex internal mechanism that implements a 365 day calendar and automatic daylight compensation. The metal pins that operate the time switch are mounted to a pair of rotating levers that move independently of the main dial. These levers are positioned by a 364 tooth calendar gear that completes one rotation relative to the main dial every year, allowing the switch to automatically match the operating time of the streetlamp to the length of the day.


General Electric 3T18SOL2, cover open. Note the Telechron synchronous motor in the upper corner.

The 3T18SOL2 implements an automatic calendar for length of day correction. The time of day can be set with the small wheel in the lower right of the photo.

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