Kiripolszky Károly

@karoly.kiripolszky

Nanosized FPV racing drone from H8 Mini

The H8 Mini was the first quadcopter I fell in love with. However, in spite of the common belief, I dare to think it isn’t really for indoors or suitable for a beginner due to it’s speed, agility and crazy yaw rate. One should rather take that bad boy outside, so the obvious next step would be adding FPV equipment to it.

I’ve seen many videos on YouTube of people simply sticking an AIO camera on the H8 and flying around right after; so I got myself a FX797T camera and tried to do the same. For some reason, this has never worked for me well. I had to apply too much throttle even to take off and the quad didn’t seem to be struggling with the extra weight though, controlling it wasn’t easy. I even removed the prop guards and the camera case, the trouble with the control remained. At this point I have to mention that I use my Devo 7E transmitter to control the H8 Mini, to which I have added a 3-in-1 RF module and flashed with DeviationTX.

And so it turned out that I needed to upgrade the motors, but the stock frame wasn’t sufficient to do so. Fortunately I bumped into the H8CF101 extension kit by Out of the Box Innovations.

Out of the Box Innovations H8CF101 frame kit

The frame kit is made specifically for the H8 Mini, but I’m pretty sure it could fit boards for many other toy drones as well. It supports 8520 motor size (for which I recommend the Sidewinder 8520 by Spintech Motors, because those motors deliver massive power) and up to 65mm props, the frame feels like cleverly designed. It is very easy to assemble and the result is aesthetically really pleasing. I especially like the motor protection caps, which are made of some kind of rubber material. You need to use something like double-sided tape to mount the PCB on the frame. The manual for the H8CF101 advises to use double-sided tape also to mount the camera on the frame, but I’ve found that a little piece of rubber band can do better, because it lets you adjust the camera position more easily. There is enough space underneath the center rod to wrap a band around the camera.

H8CF101 assembled, camera mounted using rubber band

The camera originally came with a Y-cable, which allowed to connect the camera and the quad to the same power source. While it seemed like a good idea, it soon turned out the excess wiring may easily cause problems in flight, because it could get hit by the propellers. The power is connected to the camera with really tiny solder joints, so I wanted to find a way to get rid of the extra wires without having to cut or replace them. This is because I’m not comfortable with very tiny soldering jobs. Luckily I discovered two solder pads on the H8 Mini board labelled B+ and B- and the power input pads are also labelled B+ and B-.

H8 blue board with extra battery out pads (B+ and B-)

I tested these pads and they were what I thought they were: output for the battery voltage. So I soldered two pieces of wire on them with the same type of connector the camera power cable had. Then I just wrapped the rest of the camera wires around the camera and this way I could remove about 6cm of needless wire. This is how the camera power connection looks like:

Camera connector and wiring

One of the problems I could not solve as of yet, is the USB programming connection. It is widely known that the H8 Mini (both the green and blue boards) can be flashed with custom firmware (please take a look at Silverware Wiki for more info). Flashing is pretty useful, because it gives you things like acro mode, among others, like PID tuning and telemetry. A permanent connector is necessary, since every time you need to change some software settings, you need to reflash the firmware. So the connector I used for flashing prevented me from assembling the frame properly, mainly because I put it on the side where the camera mount piece of the frame supposed to be.

Servo connector soldered for USB programming

I’m yet to figure out what type of connector I should use instead of the servo connector, because it’s obviously too big to fit. I need something smaller, but then I will also need some sort of adapter as the USB programmer has pin headers and I will still be needing a servo connector on the USB side.

The other problem is with vibrations in leveling mode. Once the quad takes off and gets airborne it begins to shake. Seems like a PID mistuning problem to me. However this does not occur when I switch to acro mode. This is also something I’m yet to inspect. It partially ties to the other problem, because changing settings means reflashing, to reflash I need a connector, but with the current type of connector I cannot assemble the frame. I will update this article once I’ve figured this out.

I’m not affiliated with or sponsored by the maker of any of the products mentioned in this article. I’m just a happy user, so I wrote this independently.

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