Hi

I am hoping to mount my go pro on a gimbal for hand held steadicam and on to a jib.

I am looking at this gimbal:

http://www.ebay.co.uk/itm/Great-Gimbal-Camera-Mount-Motor-Controller-CNC-DJI-Phantom-Brushless-for-Gopro-/131315083151?pt=UK_ToysGames_RadioControlled_JN&hash=item1e92fd278f

My questions are:
Do I need a lipo battery or will any good 12v source do?
I want to control the pitch with a servo tester like this:

Will this one do?

http://www.ebay.co.uk/itm/Etronix-3-Mode-Servo-Tester-ET0052-/281418520267?pt=UK_ToysGames_RadioControlled_JN&hash=item4185d9d6cb

I would like to manually control the camera around the vertical axis. How would I control another brushless motor?

Many thanks to anyone who can help.

Gimbal??? Wtf is that? Is it some kind of device to go on a pole to keep your camera pointing in a certain direction? Or am I way off the mark?

Yes the servo tester will work but you would have to disconnect the servo so it will no longer work under control.

Which way do you want the thing to sit and which axes do you want correcting?

An easier way might be to hack into the servos own feedback with a suitable range potentiometer at a potential divider (unless they work on optical feedback) and then you can manually adjust the angle of the servo by fooling it into thinking its in a different position

edit: just watched the video. As I suspected in my first reply which I deleted as I thought I had the wrong end of the stick there is an input channel on the device to let you use a servo tester so as far as i can tell that one should work.

ahh getting to grips with it now this bit:

1 x Pitch cable for reciver VR channel control the pitch by transmitter.

implies there is only one input channel and it controls the latter servo so no, if you wanted to control it around the other axis you are out of luck unless you hack it as above. If you can get to the sourcecode it might be possible to switch the axes round and then physically switch the leads to the servos to match and then the input channel is on the one you want.

okay a bit more…just looked at this item: http://www.ebay.co.uk/itm/New-RTF-DJI-Phantom-Brushless-Gimbal-Motor-Controller-for-FPV-BGC-3-1-Black/321481007788?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D27550%26meid%3D60d7110eaf1e421480fc9271d2daeb50%26pid%3D100005%26prg%3D11355%26rk%3D5%26rkt%3D6%26sd%3D131315083151&rt=nc

and the sensor is on the arm that the go-pro is on so hacking the servos won’t work. They also look from that image to be just stepper motors with no feedback as you get in a normal servo so definitely wont work (the only feedback is the sensor). I was originally thinking that the sensor was on the main board and it was moving the servos to correct for the main board angle.

Also seems to be definitely only one input. Options I can see are:

1. Orientate the whole thing so the channel you want to adjust is in the correct orientation (might been making a new camera mount up).

2. Hack the software and swap the servos

3. Interrupt the sensor signal somehow.

Hi Andyl

Thanks- I am happy that the gimbal hangs from the boom and stabilises as if on a ‘copter. From the youtube clip it appears that the pitch can be adjusted from a servo tester through the one input provided. I anticipated hanging the entire gimbal from another bracket so that it could be rotated manually using an additional servo but wondered if this could be done direct from a second tester or whether a control circuit was needed.

As you see, I have great ideas but little knowledge! Having spent many hours last year trying to make a mechanical steadicam that worked, I am happy to just buy the gimbal and one servo tester for a start! Can you help me about the battery?

Cheers

I was going to ask if adding another servo an option to rotate the whole thing.

Lets say X is forwards backwards, Y is side to side and Z is up down.

If you orientate the gimbal so the first servo does roll, aka tilt around the X axis, and the second (one the camera is on) is pitch, aka tilt around the Y axis, then you want to be able to add a servo to do yaw (rotate around the Z axis).

You should be able to mount a conventional servo to a servo tester to rotate the whole thing. A conventional servo has it’s own feedback circuit that works with the servo tester.

Battery wise Lithium will pack the most punch for the weight. Is 12V a common voltage for multi-rotor RC copters? Servos/steppers normally operate on 5V so it might be possible to operate at lower but if not you could always use a simple DC step up module like this: http://www.ebay.co.uk/itm/XL6009-Adjustable-Step-UP-DC-DC-Power-Supply-with-Heat-Sink-5V-35V-LM2577-/321549901179?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item4addde1d7b

That way you could use one or two conventional 18500 lithium rechargeable cells in a holder (3.2V each to give 6.4V than up it to 12V with the LM2577) or you could possibly use 4 high capacity AAs but they won’t last very long. I can’t imagine the unit uses much power but constantly working over a long period may use more than you think. Of course you could also use 4 lithium cells but check the input range of the module as it may need to be regulated.

I have a 5W torch that uses single 18500 batteries and has a charger that charges two of them so you should be able to pick up a charger and battery box up quite easily as they are very common.

Remember the servo tester will also need power but that might be built in. I had one when I was a kid that ran off a 9V PP3 battery. We used to use it to test electronic speed controllers as it basically mimics the output of an RC car receiver.

Oh and if you get a servo tester that has 2 outputs (might be switchable) you could also control the pitch on the module as well as the yaw with the same module.

Thanks again.

I was just realising that for the slow panning that I want from the third axis, a more conventional servos would be fine. The initial set up here seems to fit the bill:

The 3s lipo battery recommended is of course 11.1v and big bangs for the weight if flying. As mine will be on the ground I was hoping to use one of the many batteries I have from old lighting systems!

I think I am happy to splash some cash on Ebay now. Will post results in due course:)

bike lights are normally just 18500 cells inside (in case you didnt know)

I suspect 12V is a recommended voltage and it will work from a range. Not much specs on those adverts but there must be a web page somewhere about them with lots more details. If in dount some kind of regulator (step up or down) can take away any doubt. Obviously they will add to the losses in the system.

Hi

The gimbal ad definitely refers to 3s lipo battery which is 11.1v. I think the ordinary servos like this

http://www.ebay.co.uk/itm/2x-MG995-Hi-Speed-Torque-M-Metal-Gear-RC-Servo-Horns-S647-/151212359913?pt=UK_ToysGames_RadioControlled_JN&hash=item2334f580e9

operate at up to 8v. I have loads of batteries from 4.7 to 14.4v lying about so something should be ok.

Cheers

ahh now I see it. I am not familiar with all the current battery terminology (used to race RC cars when the Sanyo SCRC nicad was king!).

3S means 3 cells in series hence the odd 11.1V

Should also correct my earlier post as it should have been 18650 cells and 3.7V.

Looks like it will take a range then and is deigned to take the common RC vehicle 3S battery so you could just stick to that.

It is amazing how cheap servos are these days. I remember we used to spend anything from £80 to £160 on high end race servos but you can now get something with similar specs for about £10!

Indeed – when I looked at these gimbals just a few months ago they were over £100! It is just like the bike light market. I have a couple of HID lights that cost me over £250 each a few years ago. I now use an LED system that costs £18 complete:)

I am now thinking that rc may be the way to go as I assume that a simple 2 channel controller receiver system could operate both axis functions. (Unless of course, I’m wrong)

Update

Gimbal and lipo battery bought. Took a trip to my local model shop where the helpful guy will sort me out with rc and servo in due course. Look out for blockbuster action shots!

I was wondering if you had considered using an RC unit instead of the servo tester.

You could even hack apart a transmitter to make it into more of a box. the sticks are just connected to potentiometers inside so you can just mount them to a box and put knobs on or replace them with ones of the same type and range (some are linear, some log) if they are not suitable for panel mounting.

Years ago I connected some old servos to turn some pots connected to the joystick port of my laptop so I could play racing games using my RC car transmitter. There is probably a gadget you can hook straight up to an RC reciever now that has USB but that was pretty much free.

More food for thought…

I’ll send a post when I get something going:)