How to connect the servo to the GR 16

Discussion in 'Cinestar 8' started by David Tivadze, Nov 17, 2014.

  1. David Tivadze

    David Tivadze Member

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    Hi,

    Just finished to assemble retractable landing gear for my cinestar 8. But no idea where to connect this white wire to receiver (or may be to FC board). I have FC board v.2.5.

    And how to set up channel on my MX20 to switch the servos on and off

    thank You in advance
    David
     

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  2. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    David:
    I'm pretty sure that the white wire is the servo control for the retract/extend. In which case you need to connect it to one of the spare channels on your radio receiver. Do you have any documentation for the landing gear?

    You don't mention what model of Radio Receiver you are using, but the general way to proceed is to plug that white wire into a presently unused channel on the receiver, then assign a switch on your MX20 to that channel. You can verify the correct operation of the switch using the Servo Monitor display.

    To assign the switch to a channel, you'll need to read the manual for the MX-20, page 52.

    Make sure that the black wire that connects to the landing gear is part of the "common" ground of the rest of the electronics otherwise the white wire by itself will not work.

    Andy.
     
  3. David Tivadze

    David Tivadze Member

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    Thank You Andy for Your instant reply, as always :)
    Unfortunately no documentation for this item, just some diagrams for assembling.

    So, the receiver is GR16.
    On my GR16 I have a connection to FC board on channel 8, as usually. Physically all other channels are free. Sorry if I say stupid things :(

    1. I doubt, do I need this UBEC for powering the servos, or I can power them directly from the receiver?
    2. On my MX20 I have 1 three position switch CTRL9 a.
    David
     
  4. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    The GR16 receiver combines all the other channels together in so-called PPM (partial pulse modulation) signal form on channel 8, but it also sends each individual channels' PWM (pulse width modulation) output to connectors 1 to 7. So, for example, you could use channel 7 for gear control by pushing the white connector onto connector 7 -- be sure to get the connector on so that the white wire is under the 7 on the GR-16 label.

    Then you need to assign CTRL9 a to channel 7 using the instruction on page 52 of the MX20 manual.

    Use the UBEC -- the receiver is not the best way to power servos -- you can obviously do it, but if the UBEC came with the kit, there is presumably a reason.

    From whom did you buy the landing gear? I'm surprised that there is no documentation (not even on-line?)

    Andy.
     
  5. David Tivadze

    David Tivadze Member

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  6. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    That web page at least confirms that the white wire is designed for use with a two-position switch and thus should respond to a PPM signal from the receiver. (The other option would have been that it responded to a TTL signal from the transistor output on the flight controller).

    Are you using MK avionics? If so you can use MK Tool to check whether your switch is sending out the correct signal on the correct channel.

    Andy.
     
  7. David Tivadze

    David Tivadze Member

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    Sure I am using MKTtool, and this CTRL9 in MKtool's Channels window shows me P5[Ch9]. It is 3 position switch, but I suppose that I can use it moving from 1 position to 3 position.

    David

    P.S. Unfortunately, only this switch is free on the MX20. So my switch sends signal to Channel 9. What is my next step, Andy :)
     
  8. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Sure. The receiver doesn't know it's a three position switch other than it will see a brief "hesitation" at the center position -- all it's looking for is the off/on values.

    Can you bench test the whole set up before you fly it? Let us know what you think of the arrangement.

    Are you going to attach the gear to a Cinestar?

    Andy.
     
  9. David Tivadze

    David Tivadze Member

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    Yes, Andy, I am going to attach this retractable landing gear to my Cinestar 8. I already test the servos with the servo consistency master (see attached pic). This tester was also in the kit, unexpectedly :)
    If there is any interest in the results I will write here about this gear, how it performed and may be post a video
    Thanks for Your help. Now I start to connect everything as You recommend in Your post

    David
     

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  10. David Tivadze

    David Tivadze Member

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    Hello to All,
    So everything works just fine at home. Waiting for normal weather to test the landing gear outside.

    David
     
  11. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Thanks for letting us know, David.
    Andy.
     
  12. David Tivadze

    David Tivadze Member

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    Here are some photos with the project "Cinestar8 with retractable landing gear"

    David
     

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