HELP with setting up a servoless payload release system

Discussion in 'First Build' started by Philbruh, Nov 12, 2017.

  1. Philbruh

    Philbruh Member

    Hi all,

    Today I put together my first quadcopter, and since all was working well I thought i'd try installing a servoless payload release mechanism:

    Currently everything lights up but the payload release mechanism won't work when I trigger it on my radio. It definitely is receiving a signal as it "clicks" and flashes when I flick the assigned switch on the radio but no movement occurs....

    Could this be a case of not enough power to the payload release, a setting on my radio, or have I not set this up correctly at all? The manual says "Modify the channels travel adjust value to 100% to trigger the device using the switch" but i'm not sure what that means. Can't find any threads or videos on this either!

    Attached an image of the setup:
    - CC3D connected to an X8R receiver via SBUS.
    - The X8R is connected to the Payload Releaser via channel 8.
    - I have setup my Taranis X9D and the X8R for the full 16 channels (8 on SBUS and 8 on the PWM pins) so the drone is controlled through SBUS and the payload release via PWM

    Attached Files:

  2. Gyro Doctor

    Gyro Doctor Electronics Tech for over 45 years

    Check out the reaction to the release signal being sent using Cleanflight or Betaflight or whatever you're using so you can "see" that
    it's not a radio/receiver problem. If the receiver IS actually responding to the signal and sending the voltage output, then it might be
    a "not enough power condition" or maybe a wiring issue.

    Use a common LED to confirm the signal is actually making it to the release mechanism. Detach the wires from the mechanism and attach them
    to the led and if that led lights up when you're trying to activate the mechanism then you know it's a "not enough power" situation.

    If that turns out to be the case then simply add an "opto-isolator" between the mechanism and the signal to it. The signal will turn on an led in the isolator
    which will then close a switch that will pass as much power as you need from the main battery to activate the mechanism. ;)
  3. Philbruh

    Philbruh Member

    Okay so I took your advice and tested it to first see if it is a radio- receiver problem. I connected the Release Mechanism --> X8R (channel 8 + same on radio) --> spare PDB (5v output) --> 3S battery, and it worked! No faults with the device or anything

    So I tried the same setup on my current build Release Mechanism --> X8R --> PDB (same model as the spare using 5v output) --> 3S battery, but this did NOT work at all! In fact the LED on the release turned solid red (not blue like it should be), but I dont know what that means (no documentation from EFlite)... It also receives no input signals or changes mode when pressing the button on the device.

    Do you think it could be my PDB? Or the fact that my PDB has all the ESC's and Flight Controller connected? Does voltage and current drop with more parts connected? Quite new to electricity so not quite sure.
  4. Gyro Doctor

    Gyro Doctor Electronics Tech for over 45 years

    I found a copy of the manual for the mechanism:

    Apparently the light being red simply means there's been a slight delay selected via the mode button,
    but that doesn't speak to the lack of proper operation of the device

    It's unlikely that voltage and/or current dropping is the problem since this device doesn't require much of either.
    To check your PDB try attaching something else that draws about the same (or more) current and see if THAT works,
    if it does then the suspect would be the mechanism it's self rather than the supply to it. ;)
  5. Philbruh

    Philbruh Member

    Thanks, yes there is a mode on the Release that is indicated by a static red LED, but the device wouldn't responded when attempting to change modes.

    I worked it out in the end. I suspected the PDB to be faulty, so I swapped it out with the spare, hooked up all the ESC nodes and the receiver powered through the 5v BEC output on the PDB and it worked. Sent signals through and the motor displayed correct movements.

    So my current setup is the following (for anyone else who is having this issue):
    - Release Mechanism --> Receiver (via PWM, channel 8)
    - Reciever --> PDB (via 5volt BEC output connected to the 2 SBUS + and - points)
    - Receiver --> Flight controller (single yellow SBUS wire connected to the remaining signal pin in the SBUS port on the receiver)
    Gyro Doctor likes this.
  6. dragger201

    dragger201 If it ain't broke, don't fix it??? You kidding?

    Phil...............uh, are you going fishing?????
  7. Gyro Doctor

    Gyro Doctor Electronics Tech for over 45 years

    :rolleyes: ... Must be .... and some place where it's "catch and release" ! :p
    dragger201 likes this.

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