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help wanted wiring RC servo's onto P2

Discussion in 'Phantom 2 Discussion' started by p fandango, Nov 2, 2014.

  1. p fandango

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    the retractable legs i'm building for my P2 use motors terminated with standard servo plugs, but i can't afford the expense of a new transmitter/receiver yet to get an 8th channel. So the plan is to have the legs work from a switch on the body of the P2, but how do i wire the servo's to wire off a normal on/off switch, & where do i get the 6volt needed

    thanks in advance Duane
     
  2. noiseboy72

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    Not that easy I'm afraid. The servo requires a signal to tell it where to move to. A simple switch will not work.

    What you would need to do is fit either something like a servo test board - which provides the correct signal and can be triggered via a switch, or fit a couple of micro-switches as limit switches and use a double pole switch to reverse power to the motor. Here's http://electronic-things.co.uk/product/ ... oCmjrw_wcB a simple servo tester.

    To get the 5V, I suggest you fit a small regulator and run from the battery supply. http://www.instructables.com/id/5v-Regulator/ it is very simple and small to build.
     
  3. N017RW

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    Your post contains the both the words motor and then servo.

    So is it a motor or servo?

    Unlike motors, servos cannot be 'driven' with just a DC voltage alone and polarity does not determine rotation direction.

    Common servos require a PWM or 'pulse width modulated' signal. The varying pulse width corresponds with/to the position the servo is moved or roatated to.

    If you do in fact have servos and without a PWM output avaialable you would need a servo driver (or tester circuit) to accomplish operation.

    You can Google servo control or similar to learn more.

    If you have [just] motors then as mentioned you still need some limiting control devices and that becomes more electro-mechanical than electronic.
     
  4. p fandango

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    ah thanks, i've already got that servo tester but was hoping for a simpler/lighter way of switching. The motors used for the retracting aren't proportionate & only start moving when you turn the knob fully to each end, so was hoping they might work with a 5v signal to lower, then 0v to raise
     
  5. noiseboy72

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    Hmm...
    Sorry, I should have been clearer (blame the beer!) It is very easy to turn a servo into a motor, it's just a case of removing the electronics.

    It sounds like the retracting motor may have some form of control, but is not a full servo. Do you have any pictures?

    Just be careful that the motor does not stall at the end of the travel - unless it is designed that way, as power consumption will be higher. It might be as simple as applying 5V to one leg for the motor to run one way and 5V to the other to get it to return - with built in limit switches, but I am doubtful.
     
  6. p fandango

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    Very sorry, some how I didn't see your post. But sorry for the lack of technical knowledge but they are actual motors, they already have a limiting system built into them & came prewired to a normal servo plug.
     
  7. noiseboy72

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    Pictures or instructions?
     
  8. p fandango

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    ah yes sorry i forgot, no instructions but you can see the retracter mechanism here. Theirs just a normal electric motor under the carbon fibre leg/rod

    [​IMG]
     
  9. CityZen

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    I think there's more to this. There's a 3-wire connection from it. A regular DC motor has only 2 wires. Are you sure it's not a servo? This looks a lot like one on Ebay that does use a servo.

    Here's an idea: assuming you're using the 7th channel of the stock transmitter for gimbal pitch, you could take the same channel, run it through an inverter (if needed), and have it control the gear as well. So when looking up, the gear is down, and when looking down, the gear is up. This may or may not meet your needs.
     
  10. p fandango

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    the 2nd set turned up today. Here's a picture with the legs in the other position, defo looks like a dc motor to me (but your right, it was from ebay). Might try linking to the gimbal & see if it works, i'm hoping to be able to set the GoPro to a wider mode (possibly even superwide) without getting the legs in shot

    [​IMG]
     
  11. N017RW

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    I found a similar device on Hobby King with a bit more descriptive information...

    https://www.hobbyking.com/hobbyking/sto ... _1pc_.html

    Based on the above it appears to be a servo 'like' device. This was further confirmed by your testing with the servo tester or whatever you used. Looks like you will need an available PWM output.

    This is not what you wanted I gather from your OP but that's what it looks like from where I'm sitting. :?

    Just one man's opinion. ;)
     
  12. p fandango

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    does look almost identical, looks like i've got no choice but to mount the servo-tester in the P2 as well if i want to switch it manually

    thanks all for the help