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Thread: Wiring up a new FPV plane with FY21, AP117. BEC's, Toroids, and general wiring Q's

  1. #1
    Forum Member
    Join Date
    Apr 2011

    Wiring up a new FPV plane with FY21, AP117. BEC's, Toroids, and general wiring Q's

    As in the title I am setting up a new plane and have a few questions

    This is going into a Bixler and I'm planning on running ~800mW 1.2 ghz (out on the tail/nose) with 2.4 ghz Frysky (likely on a wingtip - yes I know it isn't ideal but I do have a good filter for the 1.2ghz and will be testing it extensively prior to flying). The gps recever would go out on the other wing. I'm planning on having 6 digital servos for ailerons, elevator, rudder, pan and tilt that will run on their own 5v BEC. (3A - 5A burst) and the FY21 and receiver will run on a separate 5V 5V 3A BEC. Finally I'm considering putting the AP117, camera, and video tx on their own 12 v regulator (this is a step up/down type) into a DPCAV LC filter.


    1) Is it overkill to have the 2 separate BEC's? I had considered going up to 1 larger BEC but I already had these two (that have tested well for noise). I am thinking that 3A may not be enough with the digital servos even though they are spec'd at 200/240 ma draw and I'd rather not have any unwanted voltage dips to the receiver or FY21.

    2) Should I bother with the 12 V regulator? It is an extra 20 grams or so that I may not need. The camera and OSD can both work down to a much lower voltage but I'm not sure of the cutoff for the vid TX other than the power reduces as the voltage drops.

    3) I'm planning on putting a toroid(s) on the video tx wires and elsewhere. I'm still a little unsure if I should wrap all the wires together around the torroid (power,ground, mic, vid) or use a combination of separate torroids for power vs vid/mic or even one for vid, one for mic, and one for power.

    4) This appears to be all common ground so I'm thinking I will only need signal wires from the receiver to the FY21 (aside from one plug with power from the BEC), signal wire to the esc, signal wires to the servos. Sound like a good idea?

    5) Camera and vid TX. I can run the power from the BEC into the OSD and then out to the Camera and vid tx or I can run a separate power line pair to each item from the BEC and only share the vid line between these. Any thoughts on which is best? Cam draws ~ 130-150 mA, vid TX draws ~280 ish. OSD seems to draw very little (< 50? mA).

    6) Is it worthwile to put a torroid on the signal wire from the ESC to the receiver? With one wire I can use a fairly small one with a lot of wraps if it could help

    7) Likewise should I do this on the signal wires entering the receiver and FY21?

    Picture of intended installation.
    Click image for larger version. 

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  2. #2
    Forum Member
    Join Date
    Dec 2011
    Whidbey, Washington
    Aren't the servos supposed to be plugged into the fy-21, wouldn't see the need for a regulator going to them. The fy-31 is similar, but i have mine receiving power from the speed control which also supplies power to the 5v camera. The AP-117 and Vtx get their power from a separate lipo to separate the noise from showing up on the ground station. I've seen other people use an lc filter to supply power from the main lipo to go to the vtx as well. Didn't have any issues in my Headplays and the ground recordings even from 3 miles out.


    Airtruksrus Cockpit Ground Station Systems.
    Open for business:cool:
    Always under revision to make it better.

  3. #3
    Forum Member
    Join Date
    Apr 2011
    Oops.. yes error in the diagram. The diagram should be corrected now to have the pan/tilt connect to the receiver and the ailerons (2), elevator, and rudder connect to the FY21. I want the servos to be on their own power supply as testing has shown they can draw quite large power spikes and I don't want that to go through the FY21 just in case . It is another potential point of failure though :/

    Thanks for the feedback on the separate battery. If I went that route I could isolate the vid tx/camera/osd a bit but it would likely complicate the ground wiring and I'd still have the potential servo issue to deal with.

    The toroids would be more to keep the Vid TX from interfering with the RC gear rather than the opposite in this case. I've had good luck with LC filters taking out motor noise in the past as well

    New diagram :

    Click image for larger version. 

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