Rotary sensor and display

[R. Pare]

Got another ski/medical related product I'm pondering,and need a source for good ( and small), decent-to-high quality rotary sensors, electronics, and 2- digit display. The pot does not need to be super accurate - I'm not measuring something like shock movement - just capable of either 1/2 or 1 degree rotational increments -10/0/+10 degrees, preferably without having to gear it up. There are a few hundred manufactures out there, but it is hard to get a handle on who to avoid! Too many of the industrial suppliers are rather expensive, but if that is the only way to go, so be it.

Anyone with experience and suggestions?

[BLS]

Throttle position sensors. Pick one that fits your mounting requirements. Typically have full scale output voltage over 180d or less rotation. 12 bit resolution on your input yields 180 / 2048 = <0.1 degree resolution.

[R. Pare]

Probably should have been more clear on what I wrote - long day yesterday!

The sensors are not much of a problem - any RVDT will do, and the ones we used to use for bellcrank positioning would certainly do the job. The area where I have almost zero knowledge is in the electronics and displays.

What I need for a display is something with 2 digits, maybe 1/2" to 3/4" high. The display electronics only need to be able to read out -10 to 0 to +10 ( sign not necessary), and be able to be zeroed at center position with a simple push of a button - "Off", "On", and "Zero" is all I need for controls. The ability to download readings is not necessary.

[SteveG]

Richard,

How big or small do you expect the electronics/display package to be? 24 cu. in. or 2 cu. in.?

Edit - And how much are you looking to spend?

Steve

[R. Pare]

Want it in the usual racer way - as small and as inexpensive as possible!

Dirt-cheap is not necessary ( dirt-cheap as in Chinese-made RC equipment), but I'd like to keep total costs to under a couple hundred - 2 full assemblies (sensor, electronics,and readout) are necessary for every final assembly. Long-term quality ( many years of use - a few hundred thousand cycles) is more important - this will be a medical device sold to doctors.

Someone just sent me this Flex Sensor link - very interesting and would simplify things mechanically tremendously:

https://cdn-shop.adafruit.com/datash...aFlex2inch.pdf

[BLS]

I misunderstood what you were asking. I rarely use small displays since we have big LCD monitors for all data now (and have for many years). In the "old days" we would often have small displays for local information. Pretty simple, easy to get from a potentiometer to a couple digits if you can match the display input (mv, ma) with your desired range. I have no idea what kind of packaging you are looking for, but I'll toss out an example. Dirt cheap.

http://www.jameco.com/z/PMLCDL-Velle...-_2131135.html

Lots of choices...

[R. Pare]

Yes - a panel meter like that would work just fine. Forgot to look for "panel meter" when google searching for displays! Duh! Something a little bit brighter would be best ( color digits?)

Found these tilt meters that look great. No idea on price yet:

http://www.jameco.com/z/PMLCDL-Velle...-_2131135.html

My understanding is that all this could be read and driven by an Arduino.

[R. Pare]

Jesus. This new medication must really be slowing down my mind!

Hadn't thought at looking at what was already out there for digital inclinometers. Tons of 'em, and dirt cheap. Most likely I can revamp the design to use just about any that are available, and still be able to swap out to a slightly different design if the original goes out of production.

[BLS]

I have only once used an inclination measurement sensor and that was many years ago when it wasn't cheap. After that I used a weight hanging from a potentiometer shaft to get the measurement because of the expense on a machine with about 30 such measurements... It was a slow changing system and did not need quick response, so the weight worked just fine.

[R. Pare]

Some of the newer digital levels are really inexpensive - like under $40 - and claim accuracies of .2 degrees. One I found that has excellent reviews could be used as-is for this device, with the only modification needed being to add an AC power source to get rid of the batteries - cannot have a doctor having to change batteries while a patient is waiting!

The next problem I have is in sorting a laser line-projecting system that doesn't cost a bundle.

[BLS]

"and claim accuracies of .2 degrees."

I have one I bought at Home depot for around $40. I've had it for about 4 years and it always works well. I have found it is within 0.1d accurate and very repeatable. I used to check behind it but never do anymore. It just works.

[R. Pare]

Looks like projected laser lines will be fairly simple - a laser diode and a lens that projects the line. Apparently how it is done on miter saws and such.

https://www.thorlabs.com/newgrouppag...tgroup_id=9394

[Steve Demeter]

"and claim accuracies of .2 degrees."

I have one I bought at Home depot for around $40. I've had it for about 4 years and it always works well. I have found it is within 0.1d accurate and very repeatable. I used to check behind it but never do anymore. It just works.

I am wanting to check mine.

How do you verify the accuracy???

I think mine has been dropped one too many times.

[BLS]

"How do you verify the accuracy???"

Place on a fairly level surface, take reading, turn it around and take another. They should agree within the accuracy. Same as one checks a bubble level. Mine always checks within 0.1 degree.

I just went out and got mine and it is a "Husky" brand. Dirt cheap at $39.99 and it works.

http://www.homedepot.com/p/Husky-10-...9403/205999357

That was the only one available at low price when I bought mine, but looks like there are several others now, including some a bit longer than my 10" one. I just use a straight aluminum tube (2.5" square) for longer measures.

You can check further by getting the reading on a level surface, place a 90d on that surface and check against that.

[Steve Demeter]

No wonder the answer was too obvious.

Thanks