A timer with teeth

Sky at Night Magazine - - OCTOBER / FIRST LIGHT -

For ac­cu­rate track­ing on an equa­to­rial mount, the larger the di­am­e­ter of the fi­nal gear in the drive chain, the bet­ter. How­ever, this would be at odds with the goal of porta­bil­ity. Us­ing a quad­rant arm has the ad­van­tage of us­ing an ap­par­ently large drive gear in a small phys­i­cal size as only a small part of the perime­ter of the ‘com­plete’ gear is re­quired. In the case of the MiniTrack, the arm rep­re­sents a sec­tion of a gear that would have a di­am­e­ter of 290mm.

Al­though quad­rant arms have been used in other de­signs be­fore, what makes this prod­uct so un­usual is the clock­work mo­tor that drives the arm. The mo­tor used in this de­sign is es­sen­tially a one-hour timer in­stalled at one end of the body. It even pings at the end of the run to alert you to the fact that the hour is up. The clock­work mo­tor en­gages with a se­ries of in­ter­me­di­ary gears that ul­ti­mately move the quad­rant arm via a set of teeth on its curved outer edge.

Quad­rant teeth Clock­work mo­tor Quad­rant arm

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