December 11, 2015

A long story about flashing ESCs

It all started with me deciding that BLHeli with soft damping was a fundamental requirement for my next build. I bought the DYS BL10A for my upcoming 150 size FPV racer build.

From the comments section one can read that this ESC
  • has a tendency to go up in flames
  • is not programmable via the 1-wire interface 
Perfect! Not really, but I tested all the ESCs once I got them to make sure I didn't get one of those that leaks magic smoke, and they are all fine. I also ordered one extra just in case. But it was also about time that I got to re-flash an ESC, something I've considered for a long time but never got to the action.

Hooking up one of the ESCs with the DYS programmer confirmed what I saw in the forum posts, it wasn't programmable via the servo lead.

Alright, lets strip it to see what the 4-wire interface looks like.

4-wire interface on the DYS BL10A

There are 6 pads, but 2 are 5v and ground and the remaining 4 are for the communication. I found information about how to connect the pads over at Oscar Liangs blog post.

Now that I had all that figured out I made a connector, inspired by David Windeståhls connector, using a clothespin.

Clothespin connector

My intention was to use this together with a USBAsp to be able to flash a new firmware with bootloader and/or configure the ESC. But my USBAsp is a cheap one from hobbyking and appearently it has an old firmware and can't do this kind of job. So I started preparing to update the firmware of the USBAsp first. This is possible, but requires a lot of figuring out and I decided to ditch that idea.

While trying to figure out how to reflash the USBAsp I prepared one of my arduino boards to act as an ISP. This is really easy. And using the arduino I was able to connect to ESC. But for some reason I cannot get the arduino USB device to bridge into my virtual windows environment (I run Linux). And BlHeliSuite lives in windows.

I decided to use kkmulticopter flash tool to try to put a bootloader onto the chip. But for some reason the kkmulticopter tool refused to flash the chip as the ID was wrong (very little wrong, but still).

The world is against me! At this time I was close to giving up. But as a last resort I pulled out an USB ISP. Could I use this? Yes! Can I get it into windows? YES!

Alright! But this time my super duper clothespin connector failed me. For some reason I could not get a proper connection with the board.

I ended up soldering the cables directly. I wanter to know wheather it was my connector or something else that was wrong. It was fiddly. I have a crappy soldering iron without temperature regulator and I'm not a master solderer when it comes to small things.

Cables soldered to the 4-wire interface.

But it worked. I could now communicate with the chip using the USB Tiny ISP. What surprised me now was that the chip already had BlHeli v. 14, soft dampening enabled and BOOTLOADER. What? I re-flashed it! Check that everything was OK via the 4-wire interface before de-soldering it.

Didn't help. Still not possible to connect via the servo lead. Strange. So I tested the other 4 ESCs. And guess what? They could all be connected via the servo lead. So much time wasted on the one that wasn't working as it should instead of testing them all first.

December 7, 2015

OpenPilot Revolution! Wait what?!

For my upcoming 150 FPV build I really wanted to try out the Revolution nano, as my first revolution flight controller. However, as we all know, they are not easy to come by. They are always sold out at the OP store.

But wait! Right now the OP store is selling Revo nano, but only in kit form. And what kind of kit? An FPV racer kit! But come on, the kit has RCX motors and ESCs and a cheap buck voltage converter. Thats not premium stuff to go with that premium flight controller, is it? I can't buy that kit, I'm really sorry.

But then I noticed that Banggood is selling the Revo nano now. Or are they? It looks very much like a mini CC3D with different printing on the case to me. And hold on, it says "CC3D Mini Revolution" on the case. That's not even close to "OpenPilot Revolution Nano" that it should say. I'm not paying for that black box!

And what about dear old HobbyKing? Oh yes, they are also carrying the Revolution now, but only the full size version. AND they do not mention any royalties payed to OpenPilot for this flight controller, as they would usually do if they would pay them anything.

I suppose I have to wait for OpenPilot to start selling that Revo nano on its own again...

December 1, 2015

Mini CC3D

I received, among other things, the flight controller for this winter project today. I chose to go with the new mini CC3D. And yes, it is really small and will be perfect in my future 150 FPV racer.

It measures about 20 by 27 cm and to take the next step in size after the CC3D Atom the servo connector pins have been removed and it has small connector for all outputs instead.

Mini CC3D, case to the left, flight controller to the right.
Classic CC3D size in the middle for comparison.

Normally I would have removed the case to save some weight and size but it is a really tight fit and made from thin plastic which probably makes it lighter than wrapping the controller in a heat shrink tube.

I bought my specimen at HobbyKing, but you can get it from Banggood or ebay if you prefer.

October 28, 2015

Arduino garage door controller second version

I've put together the breadboard build of the garage door controller into a more compact form factor. I mounted the Arduino nano board on a small experimental PCB together with a voltage regulator. I'll be using an external voltage regulator as the internal does not supply enough power for the servo, I've seen this live when it was rebooting if the servo was moving too fast.

I tried to wrap everything in a heat shrink tube, but that failed kind of badly. I cut slots for the connectors to the switch, LEDs and servo in the heat shrink before shrinking it. Then during the shrinking process the heat shrink ripped open and parts of the pcb is still exposed. Remember that it will be installed into a doll-house that my children will be playing with and I prefer if it's a bit protected after all.

October 27, 2015

The winter build; 150 FPV racer

A while back I noticed a post on a forum where someone had built a 150 racer quad. The poster himself loved the small and nimble machine and I felt directly that this is probably something I have to build. I quickly started looking and possible components for the build and put together a spreadsheet with the options at hand.

First off was the ESC. I had specific requirements about the ESC namely that it must be BLheli and it must support 4S. And because of the form factor of the frame, it must be small. I ordered a ZTW and a DYS a while back to see the actual size (specs are often biased). And also to try to reflash the ZTW with BLheli. The ZTW has not been sent yet, but the DYS arrived today. And boy is it small. This will be my pick!

DYS 10A with 9g servo for size comparison

About the frame itself. I'm going with the Diatone ET 150 or the Diatone Blade 150. I haven't decided yet. Since the blade is quite cheap I might order both to see what they actually look like before deciding. Bit first I must cancel my ZTW order since it's no longer and option.

October 9, 2015

My first arduino; doll-house garage door controller

Now why am I writing this on an RC-blog. Well, I had (or have) big plans for the autumn. I've long had an idea to build a generic ESC programming device based on a simple arduino, connecting it to an android app using a bluetooth module.

I've started reading up on arduino the last few months and the other day I finally got a simple first project to build. See, my 3-year-old son has a doll house in which his cars live. It is a old second hand house and my wife has plans to decorate it. The first thing she did was cut a hole on one side to build a garage door. She had no idea how to make hinges so I offered her rudder hinges of course. And then it struck me. This can be much more fun with a servo on the garage door. And it went on and on and on. The master plan is to build a fully automated remote controlled doll house.

But wait a minute. I need to start somewhere. And I must not forget the ESC programmer plans.

Yesterday I built a first prototype for the garage door controller. I will use a servo and an on-off-on switch to open and close the door (my son will love it). In addition to this there is a green and red stop-light. The red light blinks as the door is moving and lit when the door is not fully open. When it is open the green light turns on.

Garage door controller, first prototype

I used a nano, which I will use for the more compact build. It's installed in an expansion shield mounted on a prototype plate with a breadboard. I don't have the switch yet so I used two push buttons instead. I used a very small servo during the development, as a 9-grammer would draw too much and make the board reboot occasionally (like when starting when the servo travels to the initial position).

The next step is to build a more compact version and decide on how to power everything. I will probably need a separate power supply for the servo to avoid it from killing the device if it gets stuck or forced by a boys playing hand.

It took me about 2 (unfocused) hours to build and program the device. Had to do the build real quick and programming while waiting for the boy to fall asleep. Surprised me how easy it was to get started, very positive first experience from arduino.

Here are the sources in case anyone is interested:

September 23, 2015

3GX MR on the T-Rex 250

I've had a T-Rex 250 DFC since a few years. I flew it a few times when it was new but after a while the gyro starting acting all weird and tilting uncontrollably. It came with a 3GX which I used. I tried setting it up over and over again to no avail. I even took it apart completely to check everything. Didn't help.

The thing is, the installation of the gyro is very tight. Most likely I had vibration issues and even additional damping tape wouldn't work. A potential issue could have been the tight cable installation. Anyway, that's all history now. I was certain I took a picture of the cabling, but cannot find it right now.

When I crashed the CopterX 250 I decided to retire it and reuse the 3GX MR from it. I installed it in the T-Rex. It made the entire installation much better. Less cables and no external receiver. After installation I was in for a great surprise. It just worked. It even flies well just like that!

The MR is actually a great solution for a helicopter that it fits in. Since almost all parameters are pre-configured in the MR there's not much to do but follow the installation instructions to the point. You cannot place servos the way you want and you must install the gyro in the given direction. The setup the present for the helicopter size and adjust servo centering and endpoints. Thats it! And it's enough!

September 13, 2015

Longer legs for the Trifecta

Last week I noticed that HobbyKing had started selling longer legs for their Trifecta frame. From the early discussions on rcgroups and by my own opinion the short legs was one of the shortcomings of the frame. Pilots fitting a small battery on the frame would be satisfied with the short legs. But even a 1300mAh battery would be nearly too big and many users use bigger batteries. The frame itself is capable of fitting quite large motors and props and many takes advantage of this and the battery that comes with such a setup.

Personally I use a 2200mAh battery. I didn't intend to in the beginning but I can use that size without compromising flight performance. Such a battery means I always belly land and take off. It comes with a few risks such as imbalance at takeoff and lipo damage at touch down. Worked fine so far but those legs will help alot in the future.

Arms legs. Old and new.

Tail leg. Old and new.

I ordered them right away and HobbyKing made a surprise delivery in only 8 (non-working) days. With el-cheapo shipping, this was a big surprise. I took the baby in the stroller to pick up the package and he was sleeping once I got back home. Perfect!

It took only a few minutes the change the legs. I had some issues with getting the old pins out to remove the old legs. But then, perfect! It doesn't look as bad as on the HobbyKing website, which gives the configuration a spidery look.

Arm with short leg.
Arm with long leg.

Tail with short leg.

Tail with long leg.

Trifecta with the new extended legs.

September 4, 2015

WLToys A979 worn out differentials

I got my WLToys A979 almost a month back. I wanted a cheap, small truggy to play around with the few times I get the opportunity. The car is really worth its price. But still, being cheap means it surely has its flaws.

I only managed to squeeze through three batteries before it started behaving badly. It had a hard time running through the grass and did make some funny noises. I quick inspection determined that the rear differential was nearing the end. But only in one direction, backwards it was working just fine. At the time, I took the differential apart and by inspection I couldn't really see any damages. But I ordered new ones right away.

I got the new differentials today. Replacing them is easy. It takes maybe 5 to 10 minutes. You'll need to loosen up 9 small screws and detach the camber links. The diff can then easily be popped out and back in its position again. I managed to do it during day time and the wife didn't even notice, now that's something!

I took the old diff apart and cleaned it up. It is now obvious that the gears are worn on one side. I tried my best to take a photo of the wear but you can't see the details really.

It is clear that the differentials on this car is one of its weaknesses. I haven't been crashing the car yet and have no idea what will break under those conditions. But even the careful driver should stock up on differentials as they obviously wear out quickly! Wltoys is probably making business out of this, since the differentials is fairly expensive in relation to the price of the entire car with radio, battery and charger included.

I got my differentials at but you'll also find them at banggood, aliexpress (cheapest atm.) and ebay.

August 28, 2015

Broken balance connector

So annoying.

Fixable. But still annoying. I'm letting this battery rest until I have nothing better to do.

August 13, 2015

3GX MR tail adjustments, impossible to reverse compensation direction

I've had a CopterX 250 standing on the shelf for some time. I used to fly it frequently two years ago but had less time last summer and one of the cyclic servos gave up in-flight. Since then it took a while before I decided to fix it and while replacing the servos I also wanted to try out the 3GX MR gyro with built-in S-FHSS receiver.

Other things caught my attention and until today it has just been standing there on the shelf. But today I decided to take care of it.

The 3GX MR is a very peculiar gyro in that it has very few configurable settings. Most settings are fixed and essentially the only thing you can adjust is servo centering (swash leveling) and endpoints in addition to the cyclic gain potentiometer and a cyclic rate potentiometer. Appearently I had almost finished everything except for one little detail, tail servo direction. It was compensating in the wrong direction.

Now, with every gyro I have ever used there has been a setting to adjust the compensation direction. One for each axis as well. On the 3GX MR? No! There is no such thing. With this gyro there is but one thing to do, move the servo to the other side of the tail boom to reverse the operating direction of the servo arm.

August 1, 2015

FQ777-124 Pocket drone

Banggood sent me the latest in the never ending series of micro quad copters; the FQ777-124 Pocket drone. This a new incarnation of the Cheerson CX-10 with a few differences like a bigger transmitter, headless mode and "one key return".

I fly a lot with the CX-10, the X4 and now this pocket drone. They are perfect for playing around calm evenings with friends, annoying the wife while she is reading and while on break at work. In particular the CX-10 is a fantastic flyer. And the pocket drone is no less!

Pocket drone to the left, Cheerson CX-10 to the right

One of the main differences is the transmitter. It is configurable for mode 1 and mode 2 operation. The quad copter can be stored inside the remote, protected during transport as well as charged via a cable using the 4 AA batteries inside the remote. It is also more ergonomic due to its bigger size compared to the Cheerson remote.

Headless mode is an excellent addition to this generation of micro quads. When headless mode is activated, using a button on the transmitter, the quad adjust cyclic commands according to the quads orientation in relation to the starting position. In effect, independently of the quads orientation, any commands given will be in relation to the pilot and not the heading of the quad itself.

I tested this mode outside, when it was a bit windy, and I was surprised how well it worked. It is important to note that the quad must be properly oriented when switch on and activated with the transmitter or it will become very hard to fly.

One key return is supposed to be a magic mode that on the click of a button on the transmitter will make the quad return to back where it started. This works not so well. It is a bit hard to determine what it actually does. It does try to come back. It has some idea of what direction home is. But not where. It misses its target and it does not stop when it should.

But the manual states that the mode should be used if the quad flies to far away and the pilot is unable to control it. And yes, it might be a saver in that case. But it is nowhere near what the icon looks like, coming back and landing on the starting point.

In addition to these two modes the pocket drone has the usual set of functions like different speed modes (2 modes), flips and rolls, trims on all channels. It also comes with some spare propellers, a USB charger and propeller protectors.

Update: Having flown it more this weekend I have discovered that

  1. It does not fly as well as the CX-10. The CX-10 has a more precise feel to the controls.
  2. Headless mode works fantastically well. No problem to pull full yaw and fly eights. Just ignore the orientation.
  3. One key return does not work. It just slowly drifts off in a random direction.

July 20, 2015


When I built my first FPV setup I guess I was lucky. I had no issues whatsoever with noise interference in the FPV transmission. However, my second setup did and ever since I have always included some form of additional filtering to counter the problem from the start.

With additional I mean that it shouldn't really be necessary. Most electronics claim to contain the filters needed to avoid any interference. But they do not always keep their promises. Especially the cheap no name stuff has this problem. The first edition of the popular TS5823 200mW mini video transmitter had it, and fixed it with an additional capacitor. But even the expensive ImmersionRC transmitter claims to be noise free (the voltage regulator I suppose). But guess what, I had problem with that one as well.

Buying LC-filters was never an option to me. They are easy to build yourself and products available on ebay used to be very expensive. But HobbyKing has changed everything now. Quite a while back they came out with the first LC-filter, speced at 1.7A. I ordered one right away, but it was too clumsy and with probably rot away in the drawer. And then, there was a smaller one at 0.7A. Ordered that one right away as well but it was out of stock and took a few weeks to get into the mail. This one is looking really nice.

LC power filters, CC3D for scale

I haven't used it in a build yet, since there isn't much building going on. But it will come to good use as soon as I put together the next FPV system.

LC power filter, top side

LC power filter, bottom side

July 6, 2015

Got some flight time this weekend

Family life is consuming most of my time this summer but I managed to get some flight time this weekend. First real flight this season in fact. A massive 3 batteries got flown, two with the 250 Ghost and one with the Trifecta.

The ghost did its job well. It felt really nice to cruise around again. This time over beaches and through the woods.

The Trifecta flew very well. LOS it feels more heli-like than quads. That whippy tail and better aileron response is probably the cause. FPV did however not feel as good. I probably need to take down the PIDs a notch, oscillation are "felt" much better flying FPV.

I also got to try out the wireless trainer. It worked well. We used yaw, aileron and elevator only in trainer mode and the student learned quickly how to get around and keep control. One little detail about the R4FA-SB receiver is that it seems to switch back to normal mode when it is bound to a new transmitter.

Unfortunately the mobius I had brought with me had given up and I got no flight footage. A friend did take some stills and we'll see how they turn out eventually.

June 19, 2015

Best HobbyKing sale so far!

The latest charger sale at HobbyKing looks like it is going to be the best sale ever.

Especially the ECO8 charger which has a 50% off which takes it down from $29.99 to $39.99. Wait, what?

Now that's a really good price for an item you cannot order. Definite must-have!

June 7, 2015

FASST wireless trainer "system"

I've always wanted a trainer/buddy box system to let others try FPV in a safe way. The cable is of course a possibility but when I finally got my hands on an old 7C I started thinking in the wireless option. Futaba has a product ( FUTM1010 ) retailing at a whooping 100$. Not really an option. I consider it overly expensive considering it is a simple FASST receiver with a cable.

And that is what I bought instead. I had noticed it before when realizing the R4FA-SB does not have the same feature set as the R6303SB. Instead of PWM output in the SBUS mode it has PPM, inverted PPM and RSSI. I didn't like it at the time but realized later what the inverted PPM is for, namely the trainer input on the futaba transmitter.

What you need:

The setup is very simple. Just set the receiver to special mode by pressing the mode button for 5 seconds and pressing again to confirm. The red LED should flash quickly. Bind the receiver to the trainer transmitter, in my case a 7C. Plug the cable into channel 1 on the receiver and into the trainer port of the master transmitter, in my case a 14SG. Done.

Add a piece of scotch tape and a piece of Velcro and the system is ready for use.

Wireless trainer system installed on the 14SG

Attention: The corona receiver might not work with EU region coded 14SG Firmware v.5 (as trainer) and the dragonlink cable cannot be used for this as the signal lead is wired to the output pin of the trainer port.

June 4, 2015

HobbyKing Mini 15A ESC

In one of the recent emails from HobbyKing they announced the new HobbyKing Mini 15A ESC. This is the first DIY:ish ESC from HobbyKing (I think) which has no cables soldered and no heat shrink applied. It is perfect for the builder who always de-solder the leads anyway. What is also peculiar is the voltage rating: 2-6S. Does anyone really believe that this $7 no-name ESC can pull 20A at 23V? Maybe it can.

My personal interest in the device is whether it is a budget alternative to ESCs like the KISS in a mini-quad or maybe a mini tri-copter build. In terms of power specs it looks good but there is no information on the firmware and no information on whether is can be re-flashed with BLHeli. And if it will survive operating with soft dampening.

From what I can see now there is only size that is comparable. So I pulled out what I had. I would have preferred a comparison with the Afro Ultra lite, the KISS and the EMAX BLHeli 12A but they are all installed somewhere. And this is what I had...

From the left: RCX 12A Sky, EMAX 12A Simon Series, HobbyKing Mini 12A

As you can see, size is not an advantage. It is small, but excluding the capacitor the EMAX is smaller. And the KISS is even smaller. I'm afraid this product is a no-go. I won't buy any more of them. The choice will still be between the EMAX, the Ultra Lite and the KISS.

May 17, 2015

Where was the locktite when I needed it?

I got a chance to fly today. During a 2 year anniversary childrens party we boys escaped from the children and took our 250 racers to the sky. I was rusty, very. Got two batteries flown during the short timeframe but managed three crashes. One knocked the headlights off. The second resulted in a 10 meter free fall after hitting a tree.

Once I found it it turns out the cage had come loose. Three screws were missing and the last one was coming off. But not broken loose. They were unscrewed. Did I not put locktite on them or is my locktite in bad condition. I had problems with bad locktite before, but this time the fault is probably all mine. I usually complete my builds before locktiting them properly. If I'm going to be this absentminded in the future, it might turn out to be a bad practice.

Do not underestimate the effect of vibrations on an RC aircraft. Secure your screws!

May 12, 2015

Driving and flying at work

For family reasons there hasn't been any building going on since my last post. In fact, the trifecta is still sitting on the bench waiting to be trimmed since the change of ESCs.

But I can't live many days without RC and I spend some time flying micro-quads and driving a car at work. Yes, a car. I had forgotten that even if it it seems simple next to flying helicopters, cars are rather fun as well.

I purchased a WLToys L939 for my 2 year old son. I picked this car because it is cheap, it has a speed setting on the remote to make it go slower, and most importantly; proportional steering.

But he wasn't interested in driving with the remote, even if he understands how it works he wants to drive it with his hands. And so, I took it with me to work instead to enjoy during breaks or while waiting for the compiler to crunch through the code. And it is a success!

March 15, 2015

Trifecta; second maiden and FPV maiden

Between painting and putting the baby to bed I managed to squeeze in a first test flight with the Trifecta after replacing the ESCs. And it was a success. It flies very well and reliably. I fitted it with a 2200mAh battery for curiosity and with this heavier battery it runs at an average of 10A. Which I think is great!

Flight data from the first flight:

Now that was yesterday. To my surprise I got an opportunity to fly today as well. This time, FPV. I usually fly LOS until I'm confident with the setup of the machine, often doesn't take many flights. So today, it was FPV time. Flying FPV gives a lot more input into the setup of the machine and its flight characteristics. I can still claim that it flies reliably and it does what you expect it too. I don't feel any insecurity in terms of maneuverability. However, there most be room for tightening the PIDs, which will be the next step. I sense a little sloppieness and there's a small bouncy feel to the stable flight.

Flight data from the first FPV flight:

March 8, 2015

Trifecta; ESC replacement

It is with mixed feelings that I come back to write this post and my last post was about my first successful flight with the Trifecta. It was also the only successful flight. Because during the second one one of the ESC started acting out.

It was equipped with a RCX Sky 12A which was a first test of this ESC to see how it performs considering the low price. Here's my review: It's big and heavy, badly put together. And it's useless.

I had already considered replacing the arms ESCs on the frame with Afros, simply because the build looked very ugly with the clumsy ESCs on the arms. And they couldn't even fold properly. I had already ordered Afros and was waiting for them when this happened. HobbyKing sent them via Singapore, bad luck I suppose, and it took a month before they arrived.

My initial configuration had the motor rotation reversed to the recommended for tri-copters. I have no idea how important this is, but I took the opportunity to correct that when replacing the ESCs. The tail ESC is a KISS and it has a solder jumper for reversing the motor direction. It took some effort to get into the frame and apply the solder.

Trifecta frame while reconfiguring tail ESC

I decided to put LEDs on the arms, something I considered doing right from the start but it didn't happen. One set of white LEDs to the front and one green and red to the back. I connected everything the ESCs. The front LEDs to the battery leads since they're made for 3S and I run the back/downwards facing from the otherwise unused BEC since they're 5V.

LEDs attached to the ESC

Not even this tiny ESC fits into the slot in the arms, I almost consider that a design flaw, 2 more millis and the ESC that HobbyKing wants to sell with the frame will actually fit. I forgot to take a photo of this, sorry. We now skip a few steps.

ESC and LEDs attached to the Trifecta arm

On the arm there's a slot for the one and only zip tie you can place on that area of the arm without it interfering with the folding. If you need more, they'll need to go on the outer part. Because of this I needed to tape down the ESC and cables and attach a zip-tie only to keep everything safe and attach the LED strip. I could have used heat shrink instead, but it will also prevent the arm from folding if located to far inwards.

The Afro ESC Ultra Lite 12A has one soft spot; the linear 0.5A BEC. On this build I'm running a receiver with telemetry, telemetry device, flight controller, FPV camera, tail servo and camera tilt servo from the BEC. And 0.5A is not enough if I want to play it safe. I installed an additional BEC on top of the frame. It adds a little weight but I hope/think it corresponds to the 5g difference between the Afro and the RCX.

March 1, 2015

Trifecta; First test flight

I did my initial CC3D configuration in the living room. This is an efficient method to get the initial settings right. But it's not final. More adjustments are needed after doing more than hovering, testing pitch pumps and windy conditions.

Yesterday was the season opening at the local flyers club and I brought to Trifecta to give it its first spin. With success. It was windy and cold and it flew as expected with slight tendencies to oscillations, quite common after an in-door setup.

In terms of result I had an average current of 9.5A. I was mostly hovering but it was also cold outside which led to a lower-than-usual voltage reading on the battery. The two factors may or may not compensate for that and I'm expecting a higher current draw while flying. Considering this I will probably need to increase the battery size slightly to get a respectable flight time. I will test it with a 1800 and 2200 in the future.

I took it for a second spin today with less success. I strapped a larger battery on it to get some current measurements while flying it a little heavier, some 90g more, totaling at 650g. What happened now is that one of the motors starts to skip. I have no idea why nor why it didn't happen the last flight. I have sent a message to the vendor of the motor and ESC to ask them.

February 12, 2015

Last parts for the Trifecta just arrived

It's not because it took a long time to ship them but more because it took a long time for me to decide to finally order them. The two last pieces for the Trifecta just came in the mail. First off is the video transmitter. There isn't much of a choice here considering limited space on the frame. I've had great experiences with the Skyzone TS5823 before and I'm going to use it again on this frame. I see no reason to use the expensive and clumsy Fatshark and ImmersionRC transmitter when not flying at long distances.

The second part is more of a test. It's the simple antenna mount from HobbyKing, I think it will come to good use since there's otherwise not many opportunities to attach the antennas on the frame. I'm stuck with long antennas due to the choice of a Futaba telemetry receiver, otherwise I would have picked a parkflyer receiver with a short antenna.

Skyzone TS5823 and antenna mount

February 7, 2015

Easy to use LEDs for 3S LiPo

I read a post on LEDs a while back and someone advised the OP to buy a set of QAV250 LEDs. Those LEDs are purpose built to fit the power distribution board of the QAV250 but they can be used for so much more. Being small, rigid and designed for 3-4S usage they are perfect for little add-ons to any build. I just got a pack of them from banggood yesterday and it's looking great. They are more powerful than I thought and for the price they're great. They also comes in packs of 5 and 10, even a little bit cheaper.

I'm feel some regrets that I didn't include this in the build plan for the Trifecta. Maybe I'll go back and make a place for them anyway...

February 6, 2015

Don't fly with worn out batteries

I have a worn out battery that I use on the bench for testing the parts of the machines that shouldn't consume that much. I've used the battery for this for quite some time and apparently I've forgotten how bad it really is.

Because today I tested out the settings of the CC3D in the Ghost 250 quad. And it didn't turn out that well. I noticed early that one motor was lagging and that full throttle did not punch nearly as much as it should. And after a few seconds the quad was having problems flying at all. And then one motor died.

I didn't have telemetry logging enabled. And stupidly enough I hadn't set up the voltage alarm neither. The only thing I know afterwards is that the smallest voltage reported was 6.5V. For a 3-cell. Well, I 'm surprised it flew that long. Check out the end of this video, and you'll see what happens when the battery runs out faster than you expected.

February 4, 2015


I got the telemetry sensor for the Trifecta the other day. This time I wanted to try out the Unisense-E instead of the usual e-fuelgauge that I have gotten used to. The main advantage of the Unisense-E is that it contains a vario. The vario is a air pressure sensor that reports relative altitude and rate of ascent/descent. Additionally, the sensor measures motor RPM using a connector to one of the motor leads.

Sensor with CC3D and Receiver for comparison

The device is very small considering the three built-in capabilities and the additional programming connector. However, it is offered with a few connector options, which makes it clumsier. Optionally you can get it with a hefty 4mm² wire which is only necessary for really high current installations.

I'm going to pull some 25A through it so I had to take it apart to replace the wires with lighter ones that are easier to fit inside a small air frame. Here's what's under the hood.

Unisense-E the shunt resister sensor and signal connector

Unisense-E processor and configuration port connector

January 31, 2015


Since the mega clumsy RCX ESCs I got for my Trifecta build is very far from fitting in the tail I needed something smaller. I ordered a KISS ESC 12A (20A burst!) and it came in the mail yesterday. And it is small for sure. I can probably put two of these in the tail if I wanted to. A comparison to the Afro ultra lite would be interesting but I haven't got one in the drawer at the moment. Here's the RCX 12A Sky for comparison.

RCX 12A Sky and KISS 12A

January 30, 2015

Vario-F, NOT an alternative to SBS01-A

Since my previous post on the Vario-F I've been testing the device some more. In fact, today I took it for its for flight. And I noticed two things; the variometer is not reporting correct values and the e-fuelgauge had stopped.

Only getting the Vario-F to work wasn't easy. Registering the device in the remote (I'm using a 14SG) didn't work. It wasn't even close to working. While I was reading the Futaba manual I discovered that Futaba claims their sensors come with a default slot setting and if that setting works for the installation then no device configuration is required. I figured it was worth a shot and it turns out it works. Simply select SBS01-A on slot 3 and the numbers start coming in.

The Vario-F acts as a Futaba SBS01-A. The Futaba sensor reports both relative altitude and variometer, which is rate of ascent and descent. The variometer is most useful for detecting thermal effects on a glider aircraft. This is not important to me but it's worth mentioning that the Vario-F does not report a correct value for the variometer reading. Looking at the telemetry log it seems as if there's some random number between -1 and 1 reported.

In the aircraft I was testing the variometer in there is also an E-fuelgauge. This device has been reused a few times and I think it is now in its third craft. To my surprise, it wasn't reporting an increasing mAh count while I was flying. At first I thought I broke it but it turns out that if I disconnect the Vario-F from the bus the e-fuelgauge is working as it should.

This seems kind of scary. It is possible that the Vario-F does not implement the SBUS2 protocol correctly and causes other sensors to malfunction. This is a big issue since the SBUS2 is a multi-master bus. A multi-master bus uses the notion of gentlemens agreement in terms of occupying the bus and the introduction a non-compliant devices causes other devices to malfunction.

If someone was to put critical things like a servo on the SBUS2 port together with the Vario-F? Well that would probably not end well.

January 28, 2015


A while back I pledged a few bucks to the nano beams project on kickstarter. Essentially, nano beams are like maker beams but smaller and lighter. They'll come to great use when putting custom stuff on the flying machines in the future.


January 27, 2015

FPV250 Ghost replacement LED board arrived

I got the replacement LED PCB from HobbyKing today which enables me to install the board and the motor on the almost finished FPV250 Ghost. I got the wrong LED color on one of the boards with the frame and filed a complaint to HobbyKing. They sent me a new one.

Finally I can get started with dialing in the PIDs and checking out if it looks any good in the air with those LEDs on.

January 23, 2015

Cheerson CX10 range hack and a promo

I bought a Cheerson CX-10 a while back to bring to work to fly and let others try out flying. It's a great toy and except for the propellers it won't break. At least mine hasn't broken yet. It flies real well and has a stable hover for beginners to practice altitude control and get a feeling for the controls in general.

Mine however had ridiculously short range. Both in term of range and in term of obstacles. If anything, and I mean anything, was between the transmitter and the micro-quad it would fall dead to the ground. I figured something had to be wrong will my machine. It is very cheap and you have to live with some quality issues. My first idea was that the antenna was either missing or damaged. So I took it apart.

CX-10 inside antenna

As you can see from the picture the antenna is intact but it is located right where my finger will be while flying it. Most of the signal that should disperse to the front towards will instead just warm up my finger (very little, but you get the point).

CX-10 antenna moved to the outside

The solution was easy. I just cut a slot in the plastic case for the transmitter and bent the antenna slightly to let it pass out into the free air.

CX-10 external antenna

Now the antenna extends outside the transmitter and away from fingers instead of into them. The range is no longer a problem, at least at the office. But I haven't dared to fly into the bosses office yet...

Edit: The promo has expired since long...

January 22, 2015

FPV Headlights mk2

This is my second attempt at headlights for my mini-quad(s). This particular setup is made for the FPV250 Ghost I've recently put together (build page updated continuously).

This new version will sport a better LED and reflector, namely a Cree XM-L T6 700lm replacement module. The previous version used the HobbyKing headlight and I do expect this to be much more powerful or I'll be disappointed.

I'm going with a similar setup as last time. I'll use the same voltage regulator (although I know this is wrong) but will use a relay switch instead of an electronic one. The choice of switch is due what's on the drawer, I have an non-spec electronic and a speced relay. I'm using the relay that I know can take the punch.


Parts for the headlights


As usual I start with taking a part the things that have cables. I always replace them as they never seems to be of the right length and have the right connectors. The relay switch was stripped down to see what was inside, mainly to see the quality and how I can resolder the cables.

Relay switch, top side
Relay switch, top side

Relay switch, bottom side
Relay switch, bottom side.

And wow the soldering is just fantastic on this one. Not. I soldered new longer wires for connecting to the quads power connector and soldered the wires to the voltage regulator directly to avoid the additional connector.

Switch connected to the regulator
Voltage regulator connected to the power supply.

At this point I tested the setup. I first hooked everything up to a receiver to test the relay. I ran into a small surprise there as the relay triggers somewhere at 80-90% signal, not 50% as I'd expected. One enabled I dialed in the voltage regulator to the 4.2V stated on the LED module.

Now I connected the LED. It was bright. Too bright, and started flashing after a few seconds. This seems related to heat and could be a built in protection in the module. Because it got hot very fast. So did the voltage regulator. I had to dial it down while the LED was on to get a more sane setting. Once disconnected the voltage was at about 3V.

For this kind of setup you must use a current regulated power supply. I will test this one out to see if it handles the heat over a longer period. But you should not, this is wrong!

Anyway, I mounted everything on one of my favorite maker parts, a piece of glass fiber from the rotorbits series with pre-drilled holes.

Final assembly

And mounted it with velcro and a velcro strap on the mini-quad.

Mounted on the mini-quad
Headlights mounted on the mini-quad

Unfortunately I'm still waiting for a spare part from HobbyKing to complete the mini-quad itself and I it'll take at least another week before I get it. I'll update with night flight footage as soon as I get the parts and start flying it.

January 17, 2015

Vario-F, an alternative to SBS01-A?

I'm currently underway putting together my FPV250 Ghost edition and I thought I should give it something extra aside from all those LEDs. I noticed a while back that there was a variometer alternative to the rather expensive Futaba one. It's the Vario-F from EZC RC. It's rather cheap and there isn't that much information about it on the internet. Hence the first question, does it even work?

I've tested it now. Not flown it, but I got a first impression. The thing is that they probably reverse engineered the Futaba device to let the Vario-F imitate the SBS01-A in the SBUS2 bus. But, they did not implement auto configuration. This means that you cannot hook up the device to your transmitter and register/configure it as you would with a Futaba device. No configuration means no changing bus slots. The device is set up just like the SBS01-A in the sense that it defaults to slot 3 and occupies slot 3-5.

Once you know and accept the fact that it sits on slot 3 you can simply plug it into your receiver and configure slot 3 as a SBS01-A sensor. If you have any other sensors occupying slot 3-5 then you'll have to reconfigure them. I had to do that since I had the E-feulgauge on slot 1-3 and the RSSI "Temperature" reading from the E-feulgauge on slot 4.

But it worked out well after all and after running up and down the stairs it seems to work. I don't know much about precision and speed at this point since I haven't put it to real use yet.

Vario-F from EZC RC
Update: Please read my follow-up on this device.

January 13, 2015

They got the colors wrong

I started building my FPV250 Ghost Edition that was supposed to have been ready by now, but I've had other matters to attend to. Since the trifecta is now approaching I've started building it. I quickly noticed that the small LED boards for the arms are not marked in any way. There's no way to tell if they are red or green without connecting them to a power source.

So I did.

Too much green in this one

No luck this time. I've sent a support request to HobbyKing asking for a new one. We'll see how that turns out.

January 12, 2015

The Trifecta is here

HobbyKing finally launched "their" new mini-tri-copter, the Trifecta. I and many with me have been waiting some time for it to arrive, since HobbyKing has been leaking footage of it for some time now.

The frame is a close clone/copy/improvement on the pocketdrone frame. You can essentially build a full pocket drone clone using parts from the HobbyKing store, including the flight controller which is an APM, except for the folding propellers.

I managed to order one from the first released batch. I did not order anything else at the time as I wanted some more time to think through the setup. Their recommendations for their new frames haven't always been fantastic. I'm mostly thinking of the initial specs of the FPV250. I'v decided to pick up the drive train from MyRcMart this time. The last motors I got from them looked really good and they have good test data for their motors with different propellers. Something that HobbyKing does not. Here's my pick.

I ran the setup (approximate) through eCalc and got the results below. I think they're good enough to proceed it this point.

eCalc calculation with approximate values

I won't be ordering the tail servo as there should be one amongst the ones in my drawer that is fit for the task. Additionally I will use a CC3D flight controller and install a Unisense-E sensor. This is new to me and I want to try it out as it contains current, voltage and capacity sensors along with a vario and even a motor rpm sensor. It does however come with a price. The sensor alone corresponds to almost half the price of the machine.

Update: Please see the build page for further and updated information.

January 5, 2015

Decommissioning my first mini-quad

Since I have the parts waiting for my fourth mini-quad build there's a need to get rid of one of the others. My first mini-quad has been a fantastic machine for learning and crashing but it has some short comings and I need the telemetry receiver and flight controller for my next build.

But instead of just tearing it apart and letting the parts rot in a corner I will refit it with a spektrum receiver and a KK board I'm not using and give it to a fellow hobbyist that I think should get started with FPV.

This post is for remembering the machine and some of the mistakes I made while building it.

My first FPV250, last moment before decommissioning

I'll take it appart top to bottom through the layers of rotorbits and plywood.

The video transmitter

First off is the video transmitter. The placement of the device caused the antenna connector to break away when I flew into something.

CC3D on a plate of plywood

Below the transmitter is the flight controller. An original DroTek CC3D. Loved it from the start and it made me consider the KK as crap (more an that later). I'm still using servo connector pins on this one.

Receiver and current sensor

I squeezed in the receiver in the "bay" of the frame. HobbyKing always wanted a KK to sit in here as a flight controller. The CC3D could never fit, especially considering the USB-port on the side. I used a special cable to wire SBUS into the CC3D and used two PWM ports to control the pan-tilt of the camera.

Pan-tilt coming off
The pan-tilt from fatshark was something I never liked. I had to drill and saw to be able to mount it upside down and to move the cable that annoyingly came out the back of the mount. Later on one of servos died (electronically). You don't always get what you pay for.

The current sensor
This was my third use of the current sensor from Fantastic device that just works and I have a hard time living without it now. Too bad Faastest receiver plus sensors comes with a considerable cost, otherwise all my models would have them by now.

After having removed all the electronics except for the ESC and motors I installed a KK 2.1.5 board together with a DSMX receiver. I flashed the KK with steveis latest firmware and WOW was I surprised. A lot have happened since I was trying to get my stock KK and KK++ SBUS flying and it was only flying like crap. After about 5 minutes adjusting the transmitter and the KK settings I now have a basic configuration the does what it should. Ready to give away and for someone else to give it eyes and learn how to fly.

FPV250 with KK board, the way HobbyKing wanted it