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YAW mod. Has anyone a complete walkthru with pictures?

Discussion in 'Phantom 2 Mods' started by anderb, Sep 12, 2014.

  1. anderb

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    Hi. Great forum!
    Im am getting tired of the yaw-mode being so responsive. I have seen people doing a mod putting in an extra switch and some 10k ohm resistors. but i have not been able to see a fully step-by-step with pic-mod. is there anyone out the that has a complete walkthru video, or would be so kind to make one?
    Cheers Bjoernar
     
  2. IrishSights

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    Re: YAW mod. Complete walkthru with pictures

    Your subject is a little misleading as it implys the content of you post provides a walkthru with pictures rather than a question
     
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  3. N017RW

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    Re: YAW mod. Complete walkthru with pictures

    Ditto.
     
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  4. anderb

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    Just fixed it, but still no solution to the problem.
     
  5. eagleseye

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  6. ussvertigo

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    Yaw response was my biggest complaint on shooting video with my P2 with a 2D gimbal. Most recommended a better TX like Futaba where several gain settings could be made available to slow yaw response rate. However, when the mods being talked about here came available I jumped on it and modified both my P2 TX's. But mine are not working as others have reported and I wonder about the drawings supplied in the post describing the mod. I would like to find someone on the forum that has tried this mod to converse with do determine how the wire terminations should be on the dual gang linear pot. When I switch the pot on, only the middle position of the pot gives a nice slow yaw movement in either direction. Turning the pot one way or the other from center gives non usable results. So far now, I keep it in center position (took knob off and put spot of glue on shaft to keep from changing) and switch on for video, which actually serves my purpose, but I just want to find out if I have something wrong or is it the drawing. Hope to get some feedback on this.
     

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  7. Mako79

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    Or try this with a variable adjustable resistors.


    Its much better with the adjustable resistor as you can compensate for the bias in the stock controller. You need to zero the bias on the yaw mod otherwise the phantom's camera will look slightly to one side and the phantom will fly feel like its crooked.

    I added a 10k potentiometer on the dominant yaw and lowered it until the azimuth was balanced.
     
  8. nozza87

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    I have tried and tested a few of the yaw mod's getting around and i thought i would post my results to help anyone else thinking of doing this.
    Here are the three mods i tried (plus all the trial, error and testing in between) on my Phantom 2 V+ v3:

    First i balanced the resistance from the stock yaw stick using a 500Ohm Trimpot set @ 110Ohms:
    Setting: Black ~ Yellow = Diff
    Stock: 4.71 ~ 4.82 = 0.11 kOhms (110 ohms)
    Trimpot: 4.82 ~ 4.82 = 0.00 kOhms (0 ohms)
    If you do not balance these first then you will never get the next steps to balance properly.
    The min's and max's will be different but as long as the values match when the yaw stick is centered it will be ok.

    Bypass Toggle switch + Pot:
    This was what i wanted but i there is too much difference between gangs on pot causing yaw to sway one way or the other by about 20-100 points in the DJI calibration software.

    Bypass Toggle switch + Trimpot set @ 15kOhm
    This worked perfectly but i wanted more or less control of the yaw depending on what i was doing.

    Bypass Toggle switch + Trimpot set @10kOhm + Second Toggle Switch + Trimpot set @12kOhm
    This way ended up being the best and not too complicated. Everything balanced perfectly thanks to the Trimpots and the two levels gave me the control i wanted. I opted to make switch one bypass switch two when off so if i have both switches on (slowest yaw) i only have to toggle switch one to regain full control when necessary.
    Setting: Left Value ~ Right Value
    No Switch: -1000 ~ 1000 = 100%
    Switch 1: -289 ~ 289 = 29%
    Switch 1+2: -145 ~ 145 = 14.6%

    Big thanks to everyone who has already done similar mods for giving me ideas and information.

    I will try get a video up over the next few days showing the different modes in action.


    Have fun :)
     
    #8 nozza87, May 24, 2015
    Last edited: May 25, 2015
  9. nozza87

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    Video added :)
     
  10. Scarecrow

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    Nozza87 that's a really informative post. Do you have any information on how to set the trim pots? I am assuming that you do it in the assistant software, but thought I would ask in case I am way off in my assumption.

    It's been a while since I've done anything involving electronics, and I've never had any form of training, but looking at the schematic you provided for the single switch option it looks as if you are using the 500 Ohm trimpot to balance the stock configuration, and the 2 x 20k Ohm trim pots to balance the yaw control when in reduced sensitivity mode.
     
  11. Tallyrver

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    I did the yaw mod a couple months ago .i used the adjustable resistors .
    One of the best mods I've done. I hooked up the rc to the assistant to check it first,then took it for a flight. I adjusted it so I had about 30% yaw at full .
    [​IMG]
     
  12. nozza87

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    Thanks Scarecrow,
    I first used a multimeter between the grey and the black, and the grey and the yellow yaw pot wires to check the resistance when the stick is centered. The black was 110 Ohms less so i used a multimeter to set the 500 Ohm trimpot to exactly 110 Ohms i then checked and calibrated this with the assistant software to make sure i got it correct.

    I then added the two stages of 20k Ohm trimpots with the first two matched using a multimeter to be exactly 12k Ohm each (i got to this number by tweaking and testing to the speed i wanted, anywhere between 10k and 20k is pretty good).
    I then set the second two to exactly 15k Ohm each so i would have three resistance levels, 0 Ohm, 12k Ohm, and 27k Ohm.
    Because i used trimpots it is easy for me to adjust these levels to what i need however i am pretty happy with where it is now after many tests.
    I then checked they were balanced at all three stages using the assistant software making sure to only calibrate when there is no resistance.
    I had to tweak the pots to be a little bit off matching to make them read the same values left and right in the assistant software at both stages but having them start matching made this very quick and easy.

    I highly recommended this mod as it makes filming smoothly much easier.
    I intend to do the same to the camera gimbal wheel when i get some free time

    Have fun :)
     
  13. Scarecrow

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    nozza87 thanks for the reply, should make setting up a whole lot easier. One final question, why is it necessary to include the 500 ohm trim pot set 110 ohm difference between the black and yellow wires, if this difference is already present pre-mod?

    I admit I haven't looked inside my Tx yet, and the answer may be obvious when I do, but it seems that even when the mod is switched out, you have introduced an additional 110 ohms in to the feed on the black wire.
     
  14. nozza87

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    The balancing of the stock pot is required and I'll do my best to explain why:

    The yaw can only be calibrated at stock values to allow for full range control (-1000 to 1000)
    If you add resistance to values that have a different midpoint you will end up with two values that become more and more apart the more resistance you add because of the resolution of the pot and the way the software calibrates it.

    As far as i understand the assistant software 'calibrates' the yaw by looking at it's left resolution (range) and dividing it by 1000 giving it it's incremental value.
    It then does the same for the right resolution (range).

    It does not matter that the left resolution may be 1.63 kOhms and the right is 1.49 kOhms because they both are calibrated to increment towards 1000 by the same percentage of their respective resolutions.
    E.g: Left incremental value = 0.00163 (1.63 / 1000), Right incremental value = 0.00149 (1.49 / 1000)
    If you push the stick left 50% you will get 0.815 kOhms which divided by 0.00163 = 500 (50% of 1000)
    If you push the stick right 50% you will get 0.745 kOhms which divided by 0.00149 = 500 (50% of 1000)
    Even thought the actual resistance values are different you still get 500 when at 50% due to the calibrated incremental value.

    (for the next bit i am excluding how resistors actually work and just using basic math to show the problem so the value may not be correct but they are proportionate to the actual values)
    Now if we left the pot at these stock mismatched values and added 100 Ohm resistance equally to both sides, we get:
    stick left 50% = 0.815 kOhms - 100 Ohms = 0.715 which divided by 0.00163 = 438.65 (44% of 1000)
    stick right 50% = 0.745 kOhms - 100 Ohms = 0.645 which divided by 0.00149 = 432.86 (43% of 1000)
    In this example there is only a 1% difference but that is a difference and in reality it is much higher meaning left yaw will be faster than right yaw which for most is undesirable.

    Now you might be thinking you could just adjust the two 20k trimpots individually to allow for the difference balancing out the left and right but this will not work due to the difference being a multiple of the resolution which changes at every increment towards 1000 exponentially.
    So while there is a 1% difference at 50% there may be a 1.8% difference at 20% which is nearly double the difference meaning you would need a different resistance depending on the position of the yaw pot.

    But if you balance the initial values of the yaw pot you do lose resolution on one side but it matches the resolution of the other side making their incremental values identical so when you add resistance it is also equal on both sides no matter what the position of the yaw pot.


    Clear as mud? I hope this explains it or at least helps,

    Please note: I understand there may be errors in my math but this does not matter, what matters is the basic principles of how and why this works and doesn't work which i have done my best at explaining.
     
  15. Scarecrow

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    Actually that makes a lot of sense. I was assuming that in stock mode the values for both sides would have been equal, but obviously not. Thanks, that has cleared up a yawning gap in my knowledge, and corrected what I thought was a logical assumption to make, but obviously not.
     
  16. Fyod

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    It it because the potentiometers that correspond to the stick movement are very cheap, very sloppy and it would be expensive to calibrate each pot (there are 4 total) in each controller from a manufacturing perspective. So while there is some chance of having perfectly centered pots, not all of them will be centered. In my controller, two of the four were OK. Unfortunately, the yaw was -134 off center (visually a couple degrees).

    [​IMG]

    [​IMG]