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Conceptual Design: DIY Steam Gauge Altimeter

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Aerowerx

Well-Known Member
Joined
Dec 1, 2011
Messages
6,092
Location
Marion, Ohio
There has been some recent discussion on DIY gauges, all of which use some type of solid state sensors and some kind of microprocessor chip.

Most of the discussions have focused on the gauges themselves. Either a "glass panel" like display, a numerical readout, or a combination as in CluttonFred's latest ideas.

Although I haven't decided what I am going to do for gauges, I have been pondering over how to make a multi-pointer altimeter driven by an air-core motor. A multipointer gauge would require concentric shafts and some kind of gearing system.

The problem with gears is the precision construction needed to get the gears to run smoothly without binding. I have come up with an alternative, however. Instead of a single air-core motor, use 3 driving concentric shafts:
img012 (495x640).jpg
This drawing shows the basic idea. Three air-core motors driving the three concentric shafts. Each motor has a different size ID magnet as shown. If you never go above 10000 feet (or know the difference between 2000 and 12000) you can get away with only 2 of the motors.

The magnets are available from SuperMagnetMan.net, and all the other required parts are available from various other internet sources.

I show two ways to wind the coils. The first is on a piece of plastic or fiberglass/epoxy board. The second uses a small machine screw or bolt. Although technically not "air core", the bolt idea may work better since the magnetic field would be concentrated at the end of the bolt. The diagram shows the bolt head against the magnet, which would mean a 4-40 screw for the tiny magnets are about that size. It might be better to use the end of the bolt instead of the head, in which case a #10-24 machine screw would be used.

Three SA5775AN driver chips would be required, but they can be daisy-chained so only one output from the controller is required. The SA5775AN uses a 10 bit digital input and there would certainly be some programming needed for this.



I hope this makes sense, as I am very tired tonight and can't think clearly.
 
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