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Hall sensor conversion on TX (1 down - 3 to go)

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  • #1

    Hall sensor conversion on TX (1 down - 3 to go)

    To cut a long story short, I have an old old esky transmitter which I've been using on the sim. The reason being, I don't really want to hammer the Dx6i on the sim and kill the pots before I eventually get one of my heli's flying.

    Unsurprisingly the esky pots are very cheap and create lots of glitching when moving the sticks, making it fairly impossible to do anything with finesse, it's fine for stick banging but if you're like me and trying to learn basic set manoeuvres, it's pretty hard.

    Cleaning the pots works for a couple of days but it means stripping them to legoland each time.

    The first thing I did was to change the pots but they didn't last long either lol. So the next step was to do some research and figure out a way of putting the problem to bed once and for all.

    The solution ? Hall sensors !

    These work by varying the the output voltage (mimicking pots) when in close proximity to a magnet, so no physical connection at all and no pots to wear out.

    So far I've converted one pot to a hall sensor (major headache to work it all out) and tested on the sim. It works perfectly with much better resolution than with standard pots.

    Still 3 left to do but I'll update this thread when it's all done.

    If anyone wants to know any technical details on what parts to use or how to do this conversion, I'll be happy to help out any way I can.

    Cheers

    Martin
    Martin

    Tags: None
  • #2
    Sounds a bit complex. Have you tried the vaseline method? I do like the sound of a non contact solution. I did try to do a Hall Effect practical at University in the late 60s, but it was so tricky we couldn't get it working right. Hall Effect implementation has come on a bit since then. A retrofit for a DX8 could be a good move. I do have a few cheap transmitters that work ok. Pots never used to be a problem, possibly a capacitor on the input was needed. My Fleet transmitters never had a problem. Threw them out a while back. Not sure how you get a linear magnetic field though.

    Does sound very interesting though. Something I'd like to know.
    Flasher 450 Sport. Assan GA250 with 520 tail servo, MKS DS450 cyclic.
    Multiplex Cockpit Tx, DX7, DX6i
    Blade 130-X, MSR, MSRX
    Phoenix Sim

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    • #3
      I tried the Vaseline but it only last a few days, I think the pots were probably beyond saving in all honesty. You mentioning it as being tricky brought a smile to my face lol, it took me ages to figure out exactly how to manipulate the movement so that it threw the voltage either way equally. That was the hardest part, trying to get it lined up as it's too sensitive to hold in your hands.

      If you rotate the sensor through 360 degrees it actually comes out as a sine wave but since only 60 or so degrees is require for the movement, it's actually almost a perfect linear output. Any more than 60 though and I think there would be problems.

      Teh hall sensor I'm using is the A1321EUA-T which has a passive output voltage of 2.5v (with a 5v input) and will go all the way from 0.1 to 4.99 volts according the to magnetic flux introduced. I've set mine to swing from 0.2 to 4.8v to make sure I don't reach the endpoints before I reach the end of stick travel.

      About half way through the second pot now
      Martin

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      • #4
        On a tx that dosent multiplex the signals a hall device is a cracking idea but where the signals are multiplexed it's a little harder to do so a good solution is a conductive plastic pot and they aren't too expensive and last loads longer than carbons

        I do like the "non contact" version should never wear out is it liner across the whole travel and is the centre point repeatable? Do you know yet if there will be any interaction by having two magnets on the same sstick?

        Steve
        Steve...

        Outrage RC Field Rep


        Now enhanced with some more EGS's....

        Comment

        • #5
          On a tx that dosent multiplex the signals a hall device is a cracking idea but where the signals are multiplexed it's a little harder to do so a good solution is a conductive plastic pot and they aren't too expensive and last loads longer than carbons

          I do like the "non contact" version should never wear out is it liner across the whole travel and is the centre point repeatable? Do you know yet if there will be any interaction by having two magnets on the same sstick?

          Steve
          Steve...

          Outrage RC Field Rep


          Now enhanced with some more EGS's....

          Comment

          • #6
            Hi Steve, over the 60 degrees or so travel for the TX joystick it remains linear and returns to centre perfectly every time.

            I don't think there will be any interactions between each sensor as the magnets are very small and the hall sensor is located so it virtually touching the magnet. From testing by hovering other magnets nearby I've not had any noticeable issues.

            The whole thing is only marginally longer than a standard pot. I could make it smaller, much smaller in fact if I were to use better magnets.

            Here is a pic of the second pot I've just finished prior to fitting. Please ignore the untidiness as I'm still at prototype stage but will machine the parts from Aluminium on the lathe at a later date.

            Martin

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            • #7
              Ok Update time.

              All pots successfully converted to hall sensors and after prolonged rigorous testing I have to say I'm very pleased indeed with the results.

              No juddering or glitching and now able to do perfectly smooth transitions without the tail or cyclic kicking out.

              However, to say this was a difficult task is an understatement.

              Would recommend others do this conversion ? - not unless like me you really do have a bad tx with substandard pots.

              Would I do this conversion again ? - If I knew then what I know now probably not lol

              However, I do have probably the most accurate esky tx on the planet Thinking about tearing the esky label off and putting it on ebay

              Overall, very happy with the final outcome and no more pot troubles. Only thing is since there is no physical connection, the sticks are very light, surprising how much drag pots cause tbh but I'm getting used to the new feel.

              Cheers

              Martin
              Martin

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