December 30, 2016

HobbyKing 3D-printers, Mini fabrikator and Malyan M150

No posts since october? Well, life has been busy and I haven't done any RC building what so ever. Except for a few FPV flights and drives at the office there hasn't been much to write about.

I have however purchased my first 3D-printer. And my second 3D-printer as well.

My first one was the Mini Fabrikator from HobbyKing, a branded version of the Tinyboy v1. This is a small desktop printer that comes at a very modest price. It might in fact be one of the cheapest printers that are ready to print out of the box. Because that's how it comes, ready to print. It print fairly well but has a few issues. The most problematic one is the absence of reliable bed leveling. The construction allows for adjustment of the print bed, but it is not permanent. When removing a print from the bed it will lose the previously adjusted position.

Other drawbacks are things like the lack of heated bed, the very small build volume and lack of spool holder and SD-card print capability. But those are merely features and should come as no surprise. In addition to this there is a spare part issue, I'll get back to that.

My second printer is a Malyan M150. It is a near clone of the Wanhao Duplicator i3 which in turn is a build variation of the very popular Prusa i3. I got this mainly because the build volume of the Tinyboy was limiting some of the things I was making. The printer is very cheap and also comes almost completely assembled in contrast to many other cheap DIY i3 variants from China which all comes in pieces. I won't go into details on the printer, there are many detailed reviews out there already. I'm personally satisfied with the printer except for the aluminium print bed (instead of glass) and that it is quite noisy.

I would however NOT recommend anyone to purchase a printer from HobbyKing unless they know what they're doing. This is because of the lack of spare parts at HobbyKing. And this a serious issue unless you can source spare parts on your own or can consider the printer as trash when it breaks down.

I had issues with the rods guiding the print bed initially. They are not perfectly straight and the bed movement is depending on the rod being "correctly" oriented and the lubrication just right. I have tried things like lubricating more or less and twisting the rods to avoid the bed from getting stuck and the timing belt skipping. If it skips the print will break. When this started happening I check the HobbyKing website and they carry spare parts. But they are on back order, so I ordered spare parts right away. That was 3 months ago, they are still on backorder. Even worse, the Tinyboy uses 4mm belts (instead of the more common 6mm) and I cannot find 4mm parts online.

The Malyan M150 also has an issue. The SD card slot broke after about 2 weeks and won't lock down the SD card anymore. It is simply broken. I have an open issue with HobbyKing about this but they argue that I have to send the printer back for refund. I won't do that of course. Instead it would be better if they carried spare parts for their printers and then I could replace only the main board and everyone would be happy.

But they don't. And as long as they don't I cannot recommend anyone to purchase their printers at HobbyKing. There are so many other vendors, locally and online, that has great service and spare parts available for their products. Unless you are comfortable with this issue, pay the extra dollars for a more serious vendor.

Update: My package with parts for the Mini fabrikator has been sent and they have started carrying spare parts for the M150. Way to go HobbyKing!

October 12, 2016

QX90; beyond expectations

So I finally got the QX90 I ordered maybe a month ago. I wasn't sure what to expect from the odd mix of a F3 flight controller and a brushed motor setup. I had read and seen much online and people seemed to like them and similar models and 50 $ isn't that much to argue about. And I wanted a replacement for the crappy flying WLToys Q282G I have been trying to fly FPV with at work.

When it arrives it comes in a small box with "everything assembled". In fact, there isn't much to assemble at all. The simple design consists of a flight controller board with brushed ESCs and two-wire brushed motors simply pressed through a rubber bushing sitting in a hole in the carbon plate which alone serves as the entire frame. On top of that a small camera with video transmitter and antenna all soldered together. Fills its purpose perfectly. But no telemetry, and no OSD.

I ordered mine together with a FM800 FASST receiver, since I fly Futaba. I knew the only assembly step I would have to take was to solder the receiver to the board. So I did.

SP Racing F3 on the QX90

But wait someone had already been dripping their solder on the solder pads I needed to use for the SBUS connection. This gives me an indication that this model, or my specimen, was produced as an BNF (with FrSky receiver) but was downgraded to PNF as I didn't want a FrSky receiver. And this is not a very nice thing to do.

I spent some time carefully trying to heat and remove the solder from those pads. The pads are smaller than usual and I know from experience that heating those pads too much will make them come off.

FM800 on the QX90

Other than that all was setup and ready. But not really. I configured the board in cleanflight. In fact everything was already done (since it was configured for SBUS already). I only had to trim in the transmitter to cleanflight. Done?

No. The board refused to arm. I spent hours trying to figure this out. There are millions of threads on how to setup the transmitter to properly arm a naze board. But this was not my issue. The would only arm while connected with the USB cable. I could arm it with the USB and then unplug it. And fly. But once disarmed without USB it refused to arm once again. And on this unusual occasion the internet was no help to me. I finally started thinking in terms of what the USB connector provided that could make it work: Solid 5V. I figured there was either a problem with the onboard voltage regulators. Or there could be an issue with the board mounter with only two miniscule patches of foam tape to the carbon fiber plate.

I was lucky. The board wasn't faulty. I applied a patch of electrical tape to the plate before mounting the board. And it worked. And it works still.

So now for a short flight review. It's great! Very slippery in rate mode, since it's very light, but it's very responsive and precise with the pre-configured PID settings it came with. And when you need attitude/angle mode, it's there for you and it is good. The quad straightens up i a split second to get your orientation right. The angle mode doesn't even makes you feel hindered while flying like I've experienced before. But that might be because I'm indoors in the office and I don't dare pick up too much speed anyway.

September 6, 2016

Fabrikator mini, first print

I got my Fabrikator mini yesterday and I must say I'm a bit impressed. It is probably the cheapest 3D printer available. And yes, it has its limitations like print size and the non-heated print bed.

But wait. It comes assembled and all you need to do before using it is screwing the bowden tube to the extruder and adjusting the Z-axis limit. Then type in the settings in the repetier configuration boxes and press print.

Here's my first print. Fantastic!


And my second. Not so fantastic.


Ok. It doesn't get everything right just yet. I have no idea what caused this. Seems as something was slipping on the stepper motor.

Now. Back to printing!

September 3, 2016

Receiver upgrade WLToys A979

This is my only build this summer. With two small kids and a 120 year old house, well, I hope this is a low mark in hobby time...

Anyway. I always wanted to replace the transmitter that came with the WLToys A979 that I got for my eldest son. For two major reasons and many minor. First off I hate RTF radios as they occupy what little space I have in my hobby corner. Secondly, I wanted to be able to make adjustments to make it easier for my son to play with the car, such as capping the throttle and adding some expo to the steering. The intention is of course to use my Futaba 4PLS as radio.

You cannot just replace to receiver in this car to achieve this. It is equipped with a 3-in-1 electronics unit which contains receiver. ESC and servo controller. Servo controller? Yes, it has a 5-wire servo which is a servo without electronics itself. Instead the two extra cables are connected to the potentiometer in the servo and the controller electronics is in the 3-in-1 unit. This is a shocker to me, but apparently the chineese like it this way. In essence it means that you need to replace everything. Well, you can keep the motor.

It took me some time to get the right stuff. I thought I had a servo that would fit so I only ordered receiver and ESC. But at the bench I realized I didn't have a proper servo. So I figured out which one to get, ordered that, waited. And then I put everything together. But silly me got it all wrong, I though I could use any brushed ESC and just get the programming right. But nope, you cannot use a brushed ESC made for airplanes in a car. It won't break (on command). It won't reverse. And it won't accept mid-stick as neutral. Even the fanciest of remote controls will help you! So I had to order another ESC. And finally.

The parts

So. The ESC is speced at 320A. Yes. It might be true, but I would not bet on it. It fits perfectly in the car. It works. I'm probably pulling about 10A with my setup, so I won't bother with the specs.

As to the servo. I spent some time to find this one. In fact, I found it as spare parts for this car at a site online. They had done a mediocre attempt at hiding which servo model it actually is. Didn't take me too long to figure out. This one is perfect for the car, no mods needed.

The build

Not that much to say about the build. Hook the stuff up. Replace the power connector with a JST connector if you wish to use the original battery. Find a good location for the receiver which will have no natural place in the car as it was originally part of the 3-in-1 unit. Cables, yes, there will be surplus cables. In the picture below you can see all the cables, and you cannot see the receiver, because of all the cables. The serious modeler would of course shorten those cables to make it more tidy.

A979 new ESC

June 17, 2016

FM800 mini Fasst receiver

I haven't had much time building or flying lately, but I received a FM800 receiver the other day and I thought I'd do a quick follow up to my previous post. The receiver is, as expected, very small. In terms if size it is actually quite fantastic, it will fit very well inside a small racer frame. The antennas are essentially just two small cables soldered onto the board. It has a small connector and comes with a few cable options (seems to be normal servo connector, connector for APM and connector for CC3D).

I often use the Corona R4FA stripped of its shell and the servo connectors when I need a slim SBUS receiver, but unfortunately I didn't have one free of it's flying machine to compare with. So I scraped up what I had in the drawer for comparison.

From the left: FM800, Spektrum nanolite, Futaba R7003, Futaba 6208
Edit: HobbyKing is now also carrying the FM800 naming it "Futaba FM800" in the title. But I doubt it is a futaba product as other site, like banggood, carries it while only claiming it to "Futaba compatible"

May 18, 2016

Finally some small SBUS receivers for Futaba!

I've somewhat regretted last years that I decided to take the Futaba path with the 14SG instead of buying a Taranis. The Futaba is much more expensive, both the transmitter, the receivers and the telemetry devices.

More so I noticed the new "naked" X4R and D4R FrSky receivers. These small buggers comes without header pins soldered and a small connector for SBUS output directly. Perfect for SBUS installation and excellent especially for small quads which only uses SBUS to the flight controller. I want this for Futaba!

And just the other day I noticed the new FM800 Fasst mini receiver (foxtech, hobbyking) with only a connector for SBUS (and not the clumsy servo header at that). And there's more. Banggood carries a no-name S-FHSS receiver in compact format with only a servo header with SBUS. In fact, the FM800 seems quite no-name as well, not much information on the receiver online, but from the community it seems to have a lot in common with the Corona R4FA-SB when it comes to the setup procedure. I've been making a lot of use of the Corona receiver myself in exactly the way that I would use a FM800, but with some de-soldering and risk-taking.

Between the two receivers, the no-name receiver from banggood comes with long antennas, I would see this as an advantage when installing the receiver in a carbon fiber frame. And since I all my mini-quads comes in carbon, well, I would go with that one. Otherwise, a FM800 with long antennas would be nice. But the present one has soldered-on antennas and a long antenna would probably be impossible.

May 9, 2016

Tarot 960

I haven't had much time to spend building lately, family has been taking up most of my time. But I did buy a second hand Tarot 960 a while back. Why on earth I did that I have no idea. But I quickly realized there are a few things I have to improve/fix on it before I will take it to the skies.

  • Power connections; the use of the Tarot 960 connector with 3.5mm plugs looks dangerous.
  • More power connections; reuse main batteries for the gimbal and video system.
  • Even more power stuff; install a current sensor and a telemetry receiver.
  • Radio system; use S.BUS to the gimbal instead of seperate receiver.

I have now started working on it. There are a few things I will have to order which will keep it on the ground for a while. I started out with the big soldering job on the power connectors. See the image below on why I wanted to address the power connector problems.


When all this was done I started looking into the future receiver switch. But first taking notes on the present channel mapping. I intend to use a R7003SB receiver. I will use S.BUS for the Naza and the gimbal controller. At first I intended to use a PWM output for the retractable landing gears. The R7003SB can only output channel 2 and 3 as PWM when also using S.BUS and S.BUS2 outputs. I imagined that I could configure the channel mapping in the NAZA and use channel 2 or 3 for the retracts. Nope, you can't. This is why I never used NAZA before. It may be great and expensive but it really lets you down on features and configurability.

So now I need to install an S.BUS decoder for the retracts. This is no big deal but I have to order one. I'm going to use the Corona CSBD-1 that I've used before. For some reason you can only get this device from HobbyKing...

March 9, 2016

HobbyKing slim Mobius video out cable

The standard USB cable, that you connect to the mobius to get video out, quickly because rather clumsy on any aircraft. I've tried using this on my X900 tricopter, but even on that one it was quite impractical to use.

Now, on the XJ470 the mobius is mounted in a gimbal and there is an additional need to use a cable which does not interfere with the workings of the gimbal, that is, a very soft cable.

HobbyKing has a solution to both the connector and wire problem with their slim mobius cable.

This is not a fantastic product. First off the USB connector is not the slimmest they could have made. It protrudes when inserted into the connector on the mobius. I have no idea if this is necessary or not but it kind of break the case a little bit for my tight mounting in the gimbal.

Mobius with USB cable in the gimbal
Mobius in gimbal with USB connector.

Secondly it is covered with some form of goo for insulation. It is probably black silicone as I tried to apply different kinds of glue to fixate the wires in a different position. Nothing stuck to it! Also, the goo does not cover the metal solder tabs of the USB connector and they stick out through the back.

Mobius slim USB connector
Insulation goo on the USB connector.

I managed to reposition the mobius in the gimbal to get it in there, with minimal margin. I have yet to discovery if it is close enough to CG while flying. I might need to add addition weight to the camera to get it in CG on the gimbal. I solved the badly positioned cables using a minimal piece of heat shrink.

USB connector with added heat shrink
Heat shrink on the cable to bend them around and back.

March 8, 2016

More parts for the XJ470, bit still a few short

Having "planned" the xj470 in a matter of hours I still haven't gotten all the parts I need for it. But a few more came in the last few days and I salvaged a receiver and power sensor from an FPV 250 quad to keep the budget down.

Last few parts for the build, almost.

So now I've gotten a higher rated APM power sensor, since the one included in the kit was only rated at 60A. Also, I got a FPV camera with a pan-tilt assembly. I thought I had a camera in the drawer but a friend of mine had borrowed it some time back. And now it is installed in one of his quads so I wasn't going to tell him to rip it apart for me. Also on the photo is the Corona S.BUS to PWM converted (decoder), an E-feulgauge and the receiver. I'm still missing the video switch and the GPS mast, which banggood never seems to ship. But I'll cancel those and order them from ebay instead.

Additionally I will order a small FPV camera which I'll be mounting fixed straight down. This is an idea I got since the video switch has three inputs, so why not use them.

At this point I can at least continue the build by installing the power sensors and the battery lead.

February 29, 2016

Pieces of cable from Hobbyking

Really Hobbyking!? If I order 2 meters of cable, don't you think I want a 2 meter cable and not two pieces of 1 meter cable?

I recall having ordered longer lengths of wire before without this surprise. It's probably to cut some logistics and packaging costs. I can accept it this time and I rarely need lengths longer than 1 meter. But even if I wanted 3 pieces slightly longer than 0,5 meters I would have a problem and a considerable amount of waste.

February 14, 2016

Turnigy Mobius gimbal and the ZYX BMGC controller

I've got a Turnigy mobius gimbal from HobbyKing for the XJ470 build. I got this at a bargain price during the black friday sale for only $25. It includes the gimbal, motors and the controller.

The controller is a Tarot BMGC (T-2D) which is originally designed for the Tarot GoPro gimbal. Chris at HobbyKing obviously figured out how to reconfigure it to work with a gimbal designed for the mobius instead and they didn't need to design their own for the mobius gimbal.

I probably hit all obstacles while setting up the gimbal. Make no mistake, it has to be assembled and fully configured before it works with a mobius and the motors that are bundled, otherwise it will just go crazy.

I use a virtualbox installation of windows in a Ubuntu machine, which adds some additional issues. Windows users won't see those of course.

Linux configuration

First off, you need to get the right permission for the included dongle device. Almost all RC-equipment that connects to you computer uses a dongle which is a USB-UART serial adapter. But instead of using a generic device all vendors sells or bundles their own device, like the DYS ESC programmer, the Futaba CIU-2, the BeastX dongle. The list can be made long. In this case it is a "Prolific" device and this particular device has no preconfigured udev rules in Ubuntu. As always. To fix this and make it usable add this line to a new or existing file under /etc/udev/rules.d/.

SUBSYSTEM=="usb", ATTRS{idVendor}=="067b", ATTRS{idProduct}=="2303", GROUP="users", MODE="0666"

Please note that those permissions may not adhere to your personal security preference.

Virtualbox configuration

Running the Tarot configuration programme in a virtual windows machine might not work. For me it just immediately exits with the message "Program has exised!". If found this page about the issue and in the comments you can find the solution. It's a bit outdated now. In fact, while installing the addons you should check the "3D Support (experimental)" and you will then get a dialogue asking something like "Would you like WDDM or just basic 3D". Click "Yes" and everything will be fine.

Flashing and configuring

I had some problems with vibrations in the gimbal and I decided to flash a new firmware. Although this was completely unnecessary since my controller already had version 1.5 I went ahead with it. I didn't succeed at first but with the help of this page I managed to get it done.

How to configure the gimbal with the hobbyking provided setup files is explained in the hobbyking product profile video:

Do load the hobbyking settings to the gimbal, but controller and motor configuration. Do this first before starting to play around or you'll just be waisting time. Chris got it figured out already so work with that as a baseline.

Mobius mounting

I intended to have the mobius mounted with velcro. Why? Well to be able to remove it and use it for other purposes of course. But you can't do that. The gimbal will go crazy, mine was trying to spin around until it was stopped by the sensor cabling. You must mount the mobius with the double sided tape that comes with it. Or something similar, which is not unlikely to be found in the drawer of a hobbyist. The small tape pieces that comes with the gimbal is a bit too small and a bigger piece comes will into place.

Power supply

The power supply is specified to "DC 7.4V ~ 14.8V (Recommended 12V, three lithium battery)". Which is nice. If you are running 3S at least. But I'm not. If correctly specified it will draw a max of 500mA which isn't much. I'm using my favorite mini buck voltage converter set to 12V in the frame. It will supply 12V to the gimbal, video transmitter and potentially a camera as well depending on which I choose.

S-BUS channels

The gimbal controller supports S.BUS! I didn't know this when I bought it, just lucky I guess. The gimbal has three input signals, the two axes and a mode switch. And if it hadn't had S.BUS input I would have been forced to use a S.BUS to PWM decoder to get the three signal wires to the gimbal. Now I don't have to and it will save a lot of space, wiring and complexity in the frame.

The channel mapping for S.BUS cannot be configured but are fixed. I haven't tried this out myself yet but a quick search reveals that channels 1 and 2 are used for tilt and roll and channel 5 for mode (rate or stick position). This is good to know when you start selecting channels to use in the flight controller setup. In a way it also sucks, since I will be using the R7003SB receiver and it has PWM output for channels 2 and 3. So channel 2 is wasted. In probably won't even use roll on the gimbal which makes it even more annoying.

February 9, 2016

What was I thinking?

So I started to take care of the 550 that has been sitting on my desk taking up space since last summer.

I knew there was something that wasn't pretty about the cabling, so I flipped it over on my desk.

The not-so-tidy heap of wire on the bottom of the 550.

WHAT was I thinking? Well, I had to figure this out before I could move on and do something about it. There seems to be three reasons for all those cables. First, there is a need for a Y-harness to power the gyro through the throttle connector. I'm using a CC BEC Pro and not the ESC BEC. Secondly I wanted to be able to disconnect the ESC while testing the setup, this comes handy with a Y-harness. And lastly I have used a connector between the power lead and the BEC, probably to be able to disconnect the BEC while powering the ESC. But why, I don't know.

There's a big difference between how I used to build helicopters and how I build multi-rotors. Nowadays I'm soldering almost all the cables instead of using servo connectors. To save space and weight, to cut wires to the exact length and to make it look nice. And because there is really no need for servo connectors when using flight controller boards that are not encased anyway.

But on the helicopter every component is encased. There are little to no possibility to solder wires to the components and you are therefore left out to using things like clumsy Y-harnesses. Something I would never dream of squeezing into a 250 quad of course.

So I cleaned up the installation. I had to heat up the screws to the bottom plate to remove it and attach all the wires inside the frame instead. I added a bead of hot glue to the Y-harness connectors as they felt a bit loose and left out the possibility to disconnect the ESC. Instead I will need to disconnect the motor, which has accessible wires in the front.

At the same time I flashed the new 2.0 firmware onto the CGY750 gyro which should save me some setup time when the flying season approaches. Until then I'll let the helicopter rest.

Somewhat improved cabling on the 550.

February 8, 2016

XJ470, build queue is piling up

I had future plans to build a large multi-rotor for a slightly better aerial photography than what I can do with a 250 racer today. I intended to start planning this build during spring and probably get to work with it during the summer. Being on parental leave, the hobby budget it quite tight and I did envision letting it drop if the build calculations turned out to expensive. A friend of mine built a similar sized multi-rotor a year ago and it turned out more expensive than I expected.

But then HobbyKing had a sale. A real sale. And there was lots of stuff. And I saw the XJ470 that I had never heard of before. So I quickly (maybe too quickly) scanned the forums and made my calculations. And I ordered the major parts for the build as they where on sale. It all comes down to a lot of compromises, I hope it will work out in the end.

The frame itself was at nearly half price, which was great. I ordered the frame for $60 together with a motor/ESC combo for $80. The choice fell on a MultiStar 2216 with a 20A afro ESC. The motor is speced at 3S, but community says it takes 4S and 20A might be a bit tight, but should work fine.

I picked a APM set with everything (GPS, sensors, OSD and cables and shit) for $65. The main drawback here is the lesser GPS, I would have preferred at least a 6H GPS. And it also turns out the kit does not contain a GPS mast, which surprised me as most kits do.

I will use a Mobius 2-axis gimbal. I had this one in the drawer from a previous sale where it sold at $25 (it's at $95 now).

I will be using a Futaba telemetry setup, since I can't really live without it anymore. But only receiver and power sensor will cost at least $150 and therefore I'm planning on rebuilding the Ghost 250 and replace the telemetry system with a cheap OrangeRx receiver and an OSD. That quad is not ready for decommissioning yet.

All in all I should be able to put it together for around $400. I hope. And I hope it works.

I'm looking forward to this build as it includes a lot of new technologies I haven't worked with before;

  • A bigger folding quad, capable of carrying a camera gimbal.
  • Advanced flight controller capable of autonomous flight, I've only used simple FCs so far.
  • A gimbal. With a camera.
  • Head tracking. I have an external head tracker I haven't tried yet.
  • More advanced OSD.
  • 1.3Ghz FPV system, I have the stuff and I have a license. It's about time!

But before that. I should really finish a T-Rex 550 upgrade that has been sitting half-done on my desk since last summer. And the rebuild of the Ghost 250.

February 7, 2016

CC3D adjustments for the FPV150

I did some adjustments to the PID settings of the FPV 150 today. It's very impractical as I have to unscrew the top plate to access the USB connector of the CC3D installed in the front of the air frame.

After a few adjustments I reached a good-enough setup and it flies agile and without any oscillations now.

January 26, 2016

WLtoys Q282G

I always told my friends; don't buy that shit. I was talking about mini quad-copters, ready-to-fly, with FPV capability. They've been on the market for some time and at the local shop machines like the Hubsan X4 FPV sells for about 150~200 EUR (surprisingly small price difference to Chinese vendors). And people buying the Hubsan has been very disappointed with what they got for that price tag. It might seem I'm blaming everything on Hubsan and yes they did set a low water mark with what they promised and what they delivered. But maybe things are starting to change with the next generation of cheap FPV packages.

There was a massive new years sale at banggood and I noticed the WLToys Q282G. I've had a lot of WLToys stuff before and I've always considered them price worthy. It is cheap, you get what you pay for, but isn't that bad. And this micro FPV hexacopter was down to only 55 bucks. Not only that, it had one feature that caught my eye: 5.8GHz video link. I imagined a micro FPV quad that I can fly with my goggles, at work, annoying the boss and my co-workers.

I ordered it!

Yesterday, I got it. Should I spend time on the unfinished FPV 150 or rip open the package waiting for me? Guess what I did!

I'm gonna stick to the important parts and spare you the massive review for now. First off, what's in the box.

WLtoys Q282G

You get what you'd expect in the box, plus a few extras. There's a remote control, the hexacopter itself, a video screen, some extra props and two chargers. And a memory card with a USB memory card reader!

There are two things that are a bit special about all the stuff that you get here.

First off is the video screen. It is a small screen with built-in 5.8GHz receiver and a built in rechargable battery. This isn't the top notch screen, but a cheap screen with the same functionality is at least 100 dollars on it's own. It would be better but still not very good. Other FPV micro packages would come without any screen and you'd need your own smartphone instead.

A memory card, with reader. Wow, I've never gotten a memory card with any product. Ok, it's only 4Gb but I'm still surprised.

I did a quick indoor flight to check if everything worked as expected. It flies quite well LOS, as expected. Micros have become very good and stable and this is no exception. However FPV is harder than I expected. The camera has a quite narrow field-of-view which makes it hard to fly indoors. I tried it both with the screen, which is alright for the price, and with my Fatshark goggles. But I only got through one door post and crashed when I tried to make a turn in the kitchen. Sounds like fun doesn't it?

Wait, did I say Fatshark? Yes, but no. It does not work with Fatshark. There's no way to change the frequency on the transmitter or receiver, at least not visibly and without a screw-driver. I hooked up my Fatshark goggles to my standalone video receiver and found that it was transmitting on 5.645 GHz (channel 14 in the receiver table). Video quality reception is good and you can use the Fatshark goggles this way. But the Fatsharks are not capable of receiving this frequency with the built-in receiver.

But still. I can fly this at work, with the screen and nothing more. And if people would like to try out FPV with goggle I can let them use the goggle with the standalone receiver. And all the stuff needed will still fit in my drawer at work!

January 14, 2016

Get me my propellers!

The 3545 propellers that I ordered for my upcoming 150 FPV racer didn't fit! What a big bummer! I suspected it would be tight when I got the frame and ordered a 3030 propeller right away that I really hope will work out. But it hasn't arrived yet.

Yesterday I tried to mount the 3545 propellers on the frame and it was very close a win. But not close enough, the rear props touches the standoffs ever so slightly and the front props hits both the standoff and the upper frame plate.

So now I'll have to wait. Or try to cut them down by a millimeter. But I suspect the result of the latter will be so-so, since it can be quite hard to balance a propeller of this size properly.

January 8, 2016

Started building the FPV 150

I finally started the 150 FPV racer build that I mentioned earlier. This might take a while to complete since I don't get many minutes of build time each week. At least I've managed to get the ESCs and motors in place on the frame. That was the easy part. How to squeeze flight controller, video transmitter, receiver, OSD and camera into the frame and still leave some place for a battery is still a mystery.

I've set up a build page and most build information can be found there.

January 7, 2016

FPV in the cold cold snow

I managed to fly two batteries the other day while the kid was having a nap. Unfortunately it was -16°C and that has a major impact on battery life. I only got half the flight time I would expect and almost crashed when I pushed the throttle too hard and had a voltage drop. You can clearly see the voltage drop in the telemetry graph from that flight.

First flight I had the mobius in still image capture to try to get some nice winter photos. Second flight I was playing around in the snow. The snow was new and really cold and it would have been a great day to fly a helicopter and capture some turbulence in the snow. Instead I got some on board snow footage, which could have been great if the mobius hadn't gotten full of snow right away.

Quad after racing in the snow

The quad looked quite terrifying after the flight, jammed full of snow. I blew it clean and haven't noticed any issues with the machine because of the snow so far.

January 6, 2016

Replaced an axle carrier on the e-revo

I wrecked the e-revo the other day. No, not really, but I hit a rock which looked like a grassy bump as high speed and one of the axle carriers broke. I haven't needed any spares until now and had none at all.

Broken axle carrier
Broken axle carrier

I ordered the broken part, TRA 7034. I also had to order a set of TRA 7033. This set contains the ball caps which keeps the pivot balls in place in the axle carrier. When the axle carrier broke, the ball cap was lost and unfortunately they do not come with the set of axle carriers. So now I have a lot of extra pivot balls I don't need.

Broken and new axle carrier
Broken and new axle carrier

While reading up on this particular part it came to my attention that it brakes a lot. People in the communities often call it a weak spot and upgrade it with a metal version. But I didn't. The fact that this part is cheap and easy to replace makes me think of which part will break if I upgrade this one to a metal part? Will it be the suspension arm, the drive shaft or some more central part like the bulk head? In any case the effort in repairing it will be much more substantial. This fix took maybe 15 minutes, including the "assistance" of my 3 year old son.

After reassembling the broken suspension it came to my attention to what degree this wheel was now fixed to the assembly. All the others have much more slop in the pivot balls, which I before thought was normal. It turns out that the axle carriers are worn down faster then I would expect (haven't driven this car for more that 2 hours total) and slop is introduced in the axle carrier. Unfortunately the ball caps cannot be tightened and replacing the axle carrier is the only option. There is an alternative axle carrier which has adjustable ball caps, but apparently that one is shit.

January 1, 2016

Voltage alarm in the E-Revo

I'm only using lipo batteri in my E-Revo 1/16 VXL. The car runs for quite a while on one battery and very much depending on how you run it. In contrast to flying machines the timer is not as useful. Especially when I crash a lot and pass the remote around to people to drive.

I've had the possibly bad approach to run the car until it starts feeling sluggish. This is too long. When you get that feeling you should have stopped a minute ago.

There are new speed controllers that have low voltage cutoff to protect lipos, but mine doesn't. Instead I'm installing a separate low voltage alarm into the car. I initially intended to use a simple alarm plugged to the balance lead, but it turned out to clumsy. There's really not much space under the canopy of this car.

Low voltage alarm installed in the front of the chassis.

Instead I'm using one of the many low voltage alarms out there. This particular one has two buzzer, a bright blue LED that you see clearly when it start getting dim outside. It is connected directly to the main power lead and senses automatically how many cells the battery has.

I made this installation while at the same time changing the battery connector to EC3 ( from TRX connector) and replacing the gears of the steering servo. I dabbed down the wire to the alarm using some hot glue, seems to work just fine.


Low voltage alarms like this one is not made for for car applications. In fact, the car draws a lot of power when starting from standing still which will case a half a second voltage drop and trigger the alarm. Fortunately this alarm reacts fast and does not keep on buzzing but gives a short beep and a blue flash. When power is running low the alarm will warn continuously. Works well but I did not foresee the initial warning beep that can be annoying but safely ignored.