FS700, Red Gimbal // Day 04 // Questions

Now that I’ve had this thing on the bench for a while, carefully planning the rest of the build, I’ve come up with a pile of questions.  Some of the questions I’ve gained answers to, others I’m still working on.  If you know the answer, please post in the comments.

This first set of questions I fired off to the folks at AerialPixel, where I purchased the Alexmos 70amp 6s gimbal controller:

1. The gimbal is going to be mounted on a Multi-Rotor, I see inputs on the Alexmos board for RX-PIT, RX-ROL and FC-PIT, FC-ROL, if I’m connecting this to a Spectrum RX, where do I connect Yaw input control? am I missing a component?

[Kavi] You can connect to RC Roll and assign the RC-Roll to Yaw axis. Actually there is no specific way of connecting to any particular input since you can assign however way you want in the GUI. You can use the realtime display to check which input you are connected to, the blue bar will be in the middle.


2. I’m looking through all of your documentation and I’m unclear as to which resources apply to this particular board, I have several links bookmarked but if you could direct me to the most specific resources I will dig in and start reading/watching.

[Kavi] http://aerialpixels.com/support/alexmos-6s-high-power-brushless-gimbal-controller-diagrams/

Note: Not a lot to go on here, but enough to get things wired up.
More help here: http://aerialpixels.com/support/


3. Is it ok to use 2x 3S Lipo in series? Does this board run on 4S?

[Kavi] yes you can run 2 x 3s in series = 6s [Kavi] yes you can run on 4s as well.

Note: I decided to run the gimbal using two 3S lipo batteries. I already have several 2200 mah and 3200 mah 3s lipos and they fit nicely in the dual battery housing on the gimbal. I’ll need to make a special cable for this purpose.


4. Do you have a case for this 70amp board? http://aerialpixels.com/shop/accessories/alexmos-3-axis-abs-diy-enclosure/ does this enclosure work or is this for a different board?

[Kavi]  yes with some modifications.

Note: I’ll order a project enclosure similar in size to the DIY enclosure listed on their site. It’s cheaper that way.
Aerial pixel also has a tiny enclosure for the IMU


5. The Gimbal controller kit came with 3x 3 pin header and 1x 4 pin header, what are these for

[Kavi] If you do not want to solder wired directly to the board

Note:  I’ve decided to do this, I’ll solder the 3 pin headers to the motor terminals and the 4 pin header to the imu. These pins should work with typical servo connectors so I’ll need to order a couple of those. I’ll also need to track down a 4 pin connector.


6. Do I need heat syncs?

[Kavi] no


7. Where do I get that fancy protective wire mesh?

[Kavi] we do not sell the mesh separately but you can google for that. Try to get mesh made in EU or US since Chinese ones split easy.


8. I have several assorted ferrite rings and ferrite snap rings. What goes where?

First off, what the heck is a ferrite ring used for? Read this: http://en.wikipedia.org/wiki/Ferrite_bead
The gist of it is that it acts as a filter to remove high frequency noise caused by electromagnetic fields (i.e. brushless motors) or RF.  And I surmise that ferrite rings come in many shapes and sizes, the application for each depends on the size and shape of the wire. Ferrite rings are meant for the wire to be wrapped several times and the snap-on ferrite rings snap on to larger wires.

Since we’re going to be running several wires through the middle of a gimbal motor, that potentially will add lots of noise.

Here are a few examples



9. Does the video signal require grounding? I have a limited number of conductors if I choose to use the slip ring and I think that I’ve seen folks running a video signal without a ground.

I don’t have an answer here yet, I will probably just try it out. Since the video downlink will be mounted on the X8 octocopter, I’ll need to transport the video signal from the back of the camera, through the tilt and pan axis of the gimbal (I can skip the roll axis) to a plug on the under side of the MR. I anticipate this will cause all sorts of noise in the video signal.


10. How does the remote trigger (Gentlewire Lanc Pro Cable) for the fs700 work? How is it wired up?

Just to clarify, I’m talking about the Gentles Limited gentWIRE-lancPRO Camcorder Control, model 142. (This site is confusing)

Google to the rescue, and I’ve got lots of links for you:

Here’s what I’ve learned (in theory, not in practice).  Channel 1 provides power and controls zoom. Channel 2 controls the shutter/start stop recording. You need to plug in both because without channel 1 no power to the cable. (center pin on the RX should always be 5v right?).


Thanks, if you have input please share in the comments.

About The Author

Camera/Gimbal Operator

Website developer by day and a camera/gimbal operator for Cloudgate, Inc. also by day.