Author Topic: Sine cosine potentiometer  (Read 1516 times)

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Offline woodchips

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Sine cosine potentiometer
« on: January 21, 2017, 12:13:16 pm »
Another rather nice piece of eelctromechanical engineering from the 1950's.

This is a sine cosine pot. A square mat of resistance wire with two sliding contacts at 90 degrees running over it.

Came from a coupling unit used somewhere in an aircraft navigation computer, electromechanical, an air data computer. Had several servo motors, synchros and resolvers in it. Used to convert positions from or to cartesian co-ordinates judjing by the dials. Possibly from the VC10?


Offline SeanB

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Re: Sine cosine potentiometer
« Reply #1 on: January 21, 2017, 02:43:37 pm »
Used in a lot of older aircraft, not only in the autopilot. Did part of the conversion from angle and amplitude, from a beacon or other source, to a form that could be displayed on a moving map film unit.

Had other uses as well, but those were rather proprietary in the aircraft, and often were used in the fuel system to provide correction factors.There often it was done with a biased resistance mat, with a resistance slope across it, used to give a non linear output using the standard pot style, the resistance measured across 2 points would vary depending on the position of the slider on the mat, and you could trim this to get the correct law in production.

Offline Benta

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Re: Sine cosine potentiometer
« Reply #2 on: January 21, 2017, 07:36:55 pm »
I love this kind of components, where mechanical and electrical precision come together.
Like the multi-gang tuning caps in old radios.


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