Scotty, I need power...!

Discussion in 'Radian' started by Joe Azzarelli, Sep 14, 2012.

  1. Joe Azzarelli

    Joe Azzarelli Active Member

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    So UPS delivered my christmas present today and I have been pouring over the Radian manual and videos. While this question may be academic for a seasoned RC guy, I am not a seasoned RC guy: How do I get power to the Radian and servos? What voltage is needed? Do I keep the MK FC board installed and pull power from it? I would think this would be shown on the wiring diagrams and/or pinout diagram. But alas...
    Thank you and I apologize for my thickness.

    Joe
     
  2. Matt White

    Matt White New Member

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    I'm powering mine using a voltage regulator connected to the first channel on the pan unit, since it's not in use when you use a Spektrum satellite receiver. Otherwise your power would probably come from your radio receiver, which is how I had it powered when I tried PWM.
     
  3. Brad Meier

    Brad Meier Active Member
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    I havent been able to find any real specs on voltage. Is it 5v input? Or is there a range?
     
  4. Matt White

    Matt White New Member

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  5. Brad Meier

    Brad Meier Active Member
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    Thanks Matt,

    My main concern is that I was running 11.1v to the FC2.1 when I had that mounted. Now that im stripping all that off Id like to still use all the batteries I have. I noticed the Radians can handle 12v. Does the software allow you to adjust voltage to the servos or should I get something like a CC BEC to regulate the 11.1v to 5v?
     
  6. Joe Azzarelli

    Joe Azzarelli Active Member

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    I ended up keeping the MK FC board and pulling power from it. With the battery it helps to balance against the yaw servo, and having the buzzer attached to warn of low battery for the gimbal is a nice plus.

    Joe
     
  7. Matt White

    Matt White New Member

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    I don't believe the Radian acts as any kind of voltage regulator, so if you put in 12V it's going to pass that along to the servos, which you probably don't want. I'm using as SBEC between a 2S Lipo and the Radian to step it down from 8.4V to 6V, which seems to work fine.
     
  8. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Based on what I was told by Jeff and others, the way to go is to use a 3S Lipo feeding into a BEC capable of delivering 5A (actually, I may have been told 10A in case a servo stalls) at 5v. Feed that to the receiver, then the servos get their power from the receiver. Use a second Recom/Arch 5V at 1 amp DC/DC converter to provide clean +5 to a Strato Snapper or MK IR Control. Both the BEC and the Recom have a common ground. Make sure that the receiver to Strato Snapper or MK IR Trigger servo connectors do not feed noisy power SS/MK IR.

    I discovered (the hard way -- what other way is there? See thread at http://forum.freeflysystems.com/ind...rigger-goes-catatonic-in-flight.109/#post-927), that the servos put a lot of noise back on the +5v supply line -- I presume this is back EMF and the servos don't appear have snubber diodes to prevent it. I was measuring (using a scope) as much as +4 to -2v spikes on the +5v supply line -- so much so that I burned out a Strato Snapper and the MK IR trigger didn't work reliably. The moment I added the Recom 5v for the Strato Snapper and MK IR trigger, both were rock solid -- I use only one of them not both simultaneously.

    The FC has two 78S5 Recom DC/DC converters. One it uses for +5 for the FC board itself and the other to drive the servo. Each is only capable of 5V at 1 Amp which, based on what I learned, is not enough for the three FFF servos. As I recall each servo can pull 1.5A in normal operation, more if the motion is obstructed and the servo stalls.

    I believe it's also a good strategy to use the Radian "mode control" on all servos so you can de-energize all the servos in case you need to. Like if you happened to land in a tree. Ask me how I know. :( (Summary: I failed to notice a Radian beta tilt sensor's double sided tape had almost come off when I mounted the 5DM3. Sensor then does come off in flight and flaps in the breeze. Camera counterflaps in response. Got the C8 back from out over the river/ravine but did not have control authority (or piloting skills or both) to prevent tree landing. Considering hard crushed concrete ground of dam demolition site, a tree landing turned out to be the luckiest thing to have happened. Lost some props, but no carbon fiber broke. Underwear replaced. ;) )

    Hope this helps
    Andy "head for the woods."
     
  9. Josh Lambeth

    Josh Lambeth Well-Known Member

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    That sounds scary!!! Do you have that video?

    I was also using the old FC to power my system. I then switched to a 10A castle BEC and things seem to be a much quicker response then it was on the FC.

    Josh
     
  10. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    The client has the video. Probably just as well, as I'm not sure I need to relive it! :) I'll ask if I can get a copy and post it.

    I would imagine the extra current available from the BEC would make the servos much more responsive.

    Andy.
     
  11. Jim Swanson

    Jim Swanson Member

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    Hey All,
    I'm running a Freefly HDMI converter with a Castle BEC and a 3s lipo. Down conversion is 5v.
    Can I "Y" off this BEC to run the 2 Radians and Savox servos?
    I'm thinking this might save the weight of more batteries ....if possible.

    Thanks,
    Jim
     
  12. Wing Gee

    Wing Gee New Member

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    I'm currently running 3s into a "Sport BEC" from dimension Engineering. It's only capable of 3A, but so far, it's operating fine at 6v. I'll need to put a heavier load on the gimbal and measure the current, to make sure i'm not overloading the BEC. I have a hobbywing 8A BEC, but its fairly bulky. I'll switch to it if I have to.
     
  13. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    The short answer is yes, Jim.
    The longer answer (as we say in the software business) is, yes, that should work. ;)

    If you see any video artifacts caused by electronic noise from the servos on the +5 supply, then you will need to add an independent Recom/Arch +5v DC/DC connected directly to the 3S Lipo and sharing a common "ground" (negative terminal).

    Ady.
     
  14. MIke Magee

    MIke Magee Active Member

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    I'll be programming the radians this afternoon. It's clear that the first pass should be made not attached to the servos. However (since this is a "power" thread) can/should the radians be daisy-chained to take the power from the pan to the roll to the tilt and each programmed in turn while daisy-chained?
     
  15. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    I added the Radian sensors one at a time to the "daisy chain." Pan first, roll, then tilt. Why? It just seemed more rational to do it that way so that if there was a rogue sensor, I'd be able to find it straight away. I guess I was following a basic diagnostic rule: only change one thing at a time. ;)

    Andy.
     
  16. Tabb Firchau

    Tabb Firchau Administrator
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    Yes that is correct Mike, the male to male extensions included in the kit will bring SIGNAL / POWER / GROUND from one module to the next.
     
  17. Alexander Jenal

    Alexander Jenal New Member

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    So, just to get it right... When I use the S.Bus wiring (page 10 of instruction manual), the only way to get power into the system is the red and the black cable of the S.Bus. Right?!
     
  18. John Cunningham

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    Alexander,
    The Radian will accept power on the lower 2 pins of any port - just like a normal receiver. Normally you would plug the power into your receiver then the SBUS output would take this power to the radian modules.
     
  19. kjetil tønnesen

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    hello
    i have the 3x gimble ,but i dont have radian on pan,just tilt and roll
    so how does i connect the pan servo so i can pan with my second mx 20 graupner radio

    thanks
     
  20. Tabb Firchau

    Tabb Firchau Administrator
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    You can just connect the pan servo to any of your RX ports that you want to control pan with.

    Tabb
     

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