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  1. #1
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    Multi function nob operating a servo

    I would like to know if it is possible to enable rear steering on the 1/16 e revo (operate a servo separate from others) using a multi function nob on the transmitter. I do intend to upgrade to the 4 channel version of the transmitter and I might get the docking base too if that means anything. I would really enjoy having it work. thanks for the help.

    P.S. This is all theoretical. I don't have any of the stuff yet.
    Last edited by quagman9000; 06-13-2012 at 10:24 PM.

  2. #2
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    The short answer - no.

    The long answer - if you get the 4 channel (or even the 3 channel), you can operate the rear-steer off of either channel 3 or 4(which is really a linked 4/5). Easiest to do it on the 4th channel, as it has a stock 3 position switch, which could be full left/center/full right.

    You can also mod the thumb switch from a two-position to a three-position switch, which could then also control rear steer in the same way (for details on the mod, just look at my "how to" in this forum.) However, what you won't get in either case is the ability to have proportional steering on the rear. That'd take a whole separate solution.
    Two Rusty VXLs, M2Ks 18/83 - Tag! You're it!

  3. #3
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    would I be able to remove a switch and add a dial or something to allow proportional steering and then add a switch or use a preexisting one to turn it off and have the servo center?

  4. #4
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    Great question - if you have an old AM radio that you don't use any more (I've got several...) You could take the steering wheel POT, and solder it into the channel 3 wires, and test it out easily enough. I'm not sure why, but I've been under the impression that there is some kind of limitation in the radio that makes channel three no more than 3 positions, and channel 4/5 are only 2 position (that combine to make a wonky 3 position switch).

    Maybe I'll try it out with my 3 channel radio before I install the new switch to replace the one I busted... I'm in the middle of some other Summit project stuff, though, so I'm not sure when I'd get to it.
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  5. #5
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    Quote Originally Posted by jolynsbass View Post
    The long answer - if you get the 4 channel (or even the 3 channel), you can operate the rear-steer off of either channel 3 or 4(which is really a linked 4/5). Easiest to do it on the 4th channel, as it has a stock 3 position switch, which could be full left/center/full right.
    Dude, are sure about channel 4. Channel 3, yes, as we both know well now!

    Channel 4 is only left or right, no center, same as channel 5. Is there a way of altering this you've been keeping quiet about?

  6. #6
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    Quote Originally Posted by jolynsbass View Post
    Maybe I'll try it out with my 3 channel radio
    if you do try, let me know if it works because I'm short on money to put toward this. could you tell me or give a link about what a POT is. Thanks.

  7. #7
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    Quote Originally Posted by Newth Cox View Post
    Dude, are sure about channel 4. Channel 3, yes, as we both know well now!

    Channel 4 is only left or right, no center, same as channel 5. Is there a way of altering this you've been keeping quiet about?
    I only meant that Channel 4 and 5 are linked together on a three position switch... Now that I think about it, though, because of the two different outputs on the receiver, you couldn't do a rear steer off of that. Only on Channel 3.

    I'll still test out the POT on channel 3 idea and see if it does anything good.
    (quagman, POT stands for potentiometer - it's the kind of "switch" that is attached to the steering wheel of the tx. You can look up pictures/explanations easily on google with the term "potentiometer")
    Two Rusty VXLs, M2Ks 18/83 - Tag! You're it!

  8. #8
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    thank you very much, now I fully understand what a potentiometer is.

  9. #9
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    You realise that if a TQi channel 3 will work off of a pot, I'm gonna have a fit. I'll be back to the design stage again for my crawler steering! I'm currently using using channel 3, 4 & 5 together to make it do what I want!

  10. #10
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    Quote Originally Posted by quagman9000 View Post
    thank you very much, now I fully understand what a potentiometer is.
    Just so you're clear, you can definitely do basic rear steer using a 3 channel or 4 channel Traxxas TX.

    Channel 3 can easily be modified to have a center off position. This will allow the rear steering servo to have a center position, as well as the fully left & fully right steering position.

    If the channel 3 pot mod works, that will allow more postions for the rear steering.

  11. #11
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    Thank you all. I am very pleased with what everyone has to say. keep it coming!

  12. #12
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    follow the links in the description. if you look closely at some of the pictures I think there is a potentiometer. I think he used an older radio but its the same idea right? I posted a comment asking about it.

    Here is the link http://www.youtube.com/watch?v=JSzhI...nofeather=True
    Last edited by quagman9000; 06-14-2012 at 10:28 PM.

  13. #13
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    I seem to remember someone trying it out on the newer radios & it didn't work. Course, I could be completely making that up.
    We wait to see what jolynsbass comes up with on his test.

  14. #14
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    Did the test this morning - Negative results. With a steering wheel pot pulled from one of my old AM radios, the servo on channel three did nothing. Connected to a regular three-way switch - works normally.

    Looks like you can't attach a POT to the channel 3, after all, at least on the modern (LINK, TQi) radios. Bummer. Sorry, quagman!

    (You could still use a modded three-position thumb switch for rear steer, as Newth mentioned.)
    Two Rusty VXLs, M2Ks 18/83 - Tag! You're it!

  15. #15
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    While its in bits......
    If you follow all 3 wires from the switch, where do they go to on the PCB? Straight into a chip?

  16. #16
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    does any one have any ideas to make it work like different channels, modifying the circuits maybe use a different type of potentiometer or something entirely different. I would just really like proportional rear steering without switching off of anything else. I was getting kind of excited because a lot of progress was made very quickly and it didn't seem like it would cost a lot either.

    pictures of the radio's insides would be appreciated (where the switch wires go and stuff like that)

    thanks

  17. #17
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    I looked at the pictures from the video again. I think it is a newer TQ radio with the link and he used the potentiometer from an older TQ without the link and put it in and wired it to something that he doesn't show (I will ask).

  18. #18
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    Just an after thought. He did do the 2 to 4 channel modification so maybe that allowed him something else

    here is the link to the modification http://traxxas.com/forums/showthread...-4-Channel-Mod
    Last edited by quagman9000; 06-15-2012 at 06:23 PM.

  19. #19
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    "I didn't replace the switch cause I didn't have it. my transmiter was 2ch and I turned it to 4ch by this mod:
    http://traxxas.com/forums/showthread...-4-Channel-Mod
    I believe that, that is the place where would normally be a switch.
    I used potentiometer from a new Link TQ, but you can use any linear potentiometer 100 kohms. I used the whole mechanism so that it returns to the center.
    here is the picture:
    http://imageshack.us/photo/my-images/440/tq412h.jpg/
    White wire from pot1 goes to the middle pin on the potentiometer.
    and the other two go to sides. their orientation will influence the direction of the servo.
    the potentiometer for the steering trim, you need to connect in parallel. so, yellow on yellow, green on green and white on white, but before you connect the white wire, you need to put one resistor of 4,6 kohms between white wire and steering trim potentiometers middle pin."

    those are his exact words. he said he would get on the forums tomorrow (I was kind of debating with my self about making this post but I think its better to have it than to not.)

  20. #20
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    Seems like there still may be a way to make Channel 3 fully proportional... Keep us appraised as to your results.
    Two Rusty VXLs, M2Ks 18/83 - Tag! You're it!

  21. #21
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    does anyone have any ideas on how to get another proportional channel on the TQI?

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