Electronics > Projects, Designs, and Technical Stuff
Surprise photocell circuit.
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jonpaul:
In 1950s-1960s General Electric in US and Saulter in Switzerland made astronomical time switches, a synchronous clock motor driving a 1 rev per day and one per year cam gear réduction.

The cam was cut to the equation of sunshine hours at the desired latitudes.

These were in every New York city light post and the Saulter unis on top of the luminaries, where later  the photo controls mentioned above replaced the astronomical time switch.

After a power outage all the  time switches had to be manually reset!

Just Reminiscing, from an old New Yorker

Jon

james_s:
Perhaps an interesting comparison, next to the several Watts likely consumed by the timer motor the draw from the heater in the older photocontrolls was likely an improvement.

Those old astronomical timers sound interesting, I have a few electronic astronomical timers and they're great compared to the standard kind that you have to reset all the time.
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