Just when I thought I’d finished this particular series, I decided to do an additional modification to the MJX and so it would have been completely remiss of me not to detail what I did and how things worked out. As I mentioned in Part 4, I’d been modifying the camera mount to try and get more stable shots and, even though my flying was improving, there was no way that I was going to produce smooth and steady video with these rigid mounts. I really did need a motorised gimbal and so that’s what I ended up getting, a two axis gimbal (to control pitch and roll) that kind of ticked all the important boxes and didn’t cost a ridiculous amount of money. I thought of getting a three axis gimbal, but with the type of video that I wanted to produce, a two axis should fit the bill quite well.
Now most gimbals come in a form-factor where the camera mount is more suited to the GoPro style camera but, with not much searching at all, eBay came to the fore with a much more appropriate gimbal. This is an all alloy brushless-motor gimbal with controller hardware for around $50 but, as you can see, all of the circuit boards are fairly exposed to the elements, which is pretty much what I found to be the case for all the listed gimbals. Anyway, I always have the option of using some circuit board sealant (conformal coating) to make things more weatherproof but, as I don’t intend to fly in poor weather, that’s a last resort. There were a few that had somewhat sealed housings, but they cost up to five times more and, once again, were designed more for GoPro style cameras. Notwithstanding, what attracted me the most about this gimbal, apart from the reasonable price, was the plate for holding the camera; it was perfect for the Mobius 2.
The one issue with all of these gimbals was the stated power requirement of 12V to drive the motors and, as the 2S battery that the MJX uses only supplies 8.4V maximum, I wasn’t sure how that would go. So I thought I’d get a DC-DC step-up adjustable power converter, which supposedly could take an input voltage as low as 2V and raise it to a voltage of 28V at 2A. It was also quite small, so wouldn’t add a great deal of weight to the MJX. I wasn’t sure how well this unit would work, as I watched a few videos where in some the unit worked perfectly, as long as the current draw wasn’t at its maximum, and one where it didn’t work at all and caught fire. But like with all of these ‘reviews’ you sometimes need to find out for yourself and, as the converter was so cheap ($3), there wasn’t much to lose unless it caught fire while airborne. Also, after further research, I found that the gimbal that I bought has a very low current draw, around 0.3A while operational, so hopefully the converter will cope. As it turned out, the voltage converter works very well and I might not even have to use it.
Since I already have a well established location for the gimbal, which is quite different to what many others have adopted, where they locate the gimbal underneath at the centre of the drone, I just used what I’ve been doing so far. Centre mounting means that you have to make modifications to the battery holder, how the battery is held in place and other things, which was something that I wanted to avoid. Obviously centre mounting provides somewhat better balance, but so far I haven’t noticed any real issues with front mounting of the camera, and it provides a much better visual position for the camera lens. Though the considerable extra weight will be an issue, if for nothing else than battery life. And with the weight now at 805g, it’s added considerably to the base weight. However, when I did a balance test, it’s not as front heavy as I anticipated, with the centre of gravity just behind the front legs and evenly balanced to the sides.
As it turned out, the 2-axis gimbal seems to work fine at less than the posted 12V that appears to be its designated operating voltage. The gimbal can also be connected to a PC with a USB cable and then, using available software, adjusted to enable fine tuning and other adjustable controls to be set. But I had a problem in that even though the gimbal connected to my PC, the device manager reported that the driver was not working and thus the software wouldn’t work. So after a bit of searching, I found a source for the drivers and after installing the latest version, things worked as they should. And it was the third screen shot that interested me the most, not just the calibration screen, but the ability to change the angle of the camera while out and about. By pressing a small button on the circuit board (just once as I’ve set it), you have a few seconds to adjust the angle of the camera before the camera resets to that angle. This is very handy as I have no remote control over the camera angle.
As with everything, the proof of the pudding is in the eating and, as usual, I couldn’t get out to test things when I wanted to as we suddenly had days of relentless rain. When the weather finally gave me a break, I was out at Mossvale Park once again and put the MJX through its paces. The first thing that became evident was that the front placement of the gimbal didn’t affect the ability of the MJX to fly and it appeared to be as stable as before, I certainly had no issues controlling it. However, another issue also became immediately evident, as I suspected, and that was battery power. The extra weight and with the gimbal drawing power as well, I started to experience that situation where the MJX couldn’t hold altitude for long and simply descended. So I ordered a more powerful battery to see if I could get more than just a minute of flying time before the MJX would come to earth. With a bit of luck, if the new battery is any good (there’s just too much crap about), a 5200mAh battery should be much better than an 1800mAh battery. The battery no longer fitted into the holder, so I’ve replaced that with some 3M Dual Lock.
Despite these issues, I managed to get some video but, unfortunately, it was a rather short excursion. Murphy was waiting just around the corner and the next day being more prepared, I discovered that the Mobius 2 wasn’t working. Nothing I tried would start video recording, even though the camera appeared to be turned on. So I gave up on further flying for the day to ponder back at home what had happened to the camera. Initially I thought that the battery was the problem, but even when connected to charge, nothing would happen. Also, my PC would not register the camera as being connected, so something was seriously amiss. I’ve contacted the supplier but, as with everything that you buy from overseas, warranty claims can become a bugger’s muddle. Anyway, the video that I did get before the battery gave up showed that the gimbal was working quite well. The first part is me just carrying the MJX to see how the gimbal worked hand-held, the second is the obvious flight. In the meantime, I’ve gone and ordered a Runcam 2 from a local supplier, rather than risk more money on a Mobius 2 (a follow-up story).
However, I’m still experiencing the issue where the MJX will be flying OK and then begin to descend and there’s nothing that I can do about it. After numerous tests, even when I remove the additional weight and with a much more powerful battery, the MJX is unable to sustain altitude for anything but maybe 30 sec and it was getting worse. So where to now? Since I have a second, never used, MJX, I’m going to give that a try and see if the issue is with the first MJX circuitry, having sustained many crashes during my learning period. I hope that it’s as simple as that, as I don’t want to buy a horrendously expensive drone simply for the occasional High Country Cruise.
Update 1. I’ve solved the problem. I decided to buy a 3S (12V) 2200mAh battery to see what would happen and, after testing it on the MJX with a dummy weight attached, the MJX flew without any issues. Later, when the weather improved somewhat, I returned to Mossvale Park to test out my second MJX, as the first one was now really starting to show its age. With the gimbal and camera attached, the result was perfect; the MJX flew beautifully and showed no tendency to lose power. I was a bit hesitant, but it looks like the MJX can handle the increased power and with that the increased weight. I’ll be using nothing but the 3S batteries from now on.