Originally Posted By: Ltfransky
The 1302s are linear output.

Absolutely - the sensor's output voltage is linearly proportional to the magnetic flux (within it's operating zone anyway). However:

Originally Posted By: Gene Buckle
Julian265, the setup I'm using doesn't use off the shelf joystick parts. It's all scratch built. I'm using a BI Plasma MM2 as the interface and the input curves can easily be adjusted. Keep in mind that standard pots have a 270 degree travel and most of that is wasted in joysticks that are using them.

The primary benefit here is a noise-less (electrically) system that doesn't cost an arm and a leg. A good quality pot can run well over $10 each.

I don't understand the linear vs sinusoidal thing though. If you've got a stop at 0 and a stop at 180, you're going to get a linear response line. Yes, if you go beyond the 0 and 180 points, it's going to go odd on you, but that should never happen with the kind of mechanical systems we're talking about. I suspect you may know something I don't however, so educate me! smile


If you rotate the magnets through 180 degrees around the sensor, the sensor's magnetic flux will vary according to a sine wave:

Of course you're only using the region between 90 and 270 degrees on the above graph, however you can see the slope of the line drops off as it approaches 90 and 270 degrees - in other words, you will have reduced sensitivity at the extents of stick travel. But you don't have to take my word for it: Get a protractor or other angle measurement device, start at minimum voltage and move the input shaft by 10 degrees or so, each time writing down the angle and voltage that you're getting. Then type the values into excel or other graphing program, and look at the curve you get. In the graph in my PDF, you can just see the sinusoidal influence, but my measurements were only taken over about 45 degrees of travel, or 22.5 degrees either side of neutral.

I'm not familiar with the BI Plasma MM2, and if it allows something like a lookup-table adjustment (or a curve to "linearise" a sine wave), then you'll be set. Maybe some windows/mac software already does this also? But for myself and others using the BU0836 or similar units, it's probably easiest just to get a linear response from the stick, and then apply your game-specific adjustments if needed. If for some reason (like for a throttle or knob) you need more than 45 degrees of travel, and linear response to angle, then the only way to achieve it is by using a look-up-table or carefully tuned sensitivity curve to eliminate the sine curve.