Diatone 17# / Laser230

This model is an upgrade after my first mini racing quad, the FPV250. Hopefully this build will result in some improvements from the lessons learned from the FPV250. Since the launch of the HobbyKing Laser230, which is a Diatone 17#, it became my choice of frame for this build. It's a clean-and-dirty design with the entire upper cage uncoupled from the bottom plates with rubber dampers.

The stuff

The power system

I got inspired by Bruce's build where he built his own power harness and installed it between the two bottom plates. In my case the cables go between the bottom plates of the dirty bottom ( there's a third bottom plate on the clean cage). I knew the cables on the ESCs where just about the right size and I took my time to actually de-solder the connectors to gain the extra two millimeters. At this time I also de-soldered the motor leads from the ESCs.

Two ESCs in place
Dirty plate with two ESCs

It turned out the ESCs cables were just to short anyway and that I had something in my build that Bruce didn't, the fuel gauge sensor. It turned out quite crappy. I had to extend some of the ESC wire and the placement of the cables and sensor in the center it still not fantastic. I'm not satisfied with this but it'll do. I'll probably go for a power distribution board for the next build, or choose a frame with built-in power distribution.

Power cables while soldering
Dirty plate with power harness, sensor and ESCs

As usuall, the motor mounts are not a perfect fit. The RCX 1806 uses the classic asymmetrical 12 and 16 millimeter spaced holes. However, the frame has the small holes spaced only at 12mm. The are a few different ways to mount the motors. Either the dangerous way by only attaching two screws, which might work. Or you use your favorite file and extend two holes into a slot which will make them fit, but it is a bit tedious. Or you simply take your drill out and drill a couple of extra holes and that is all it needs.

Laser230 motor mount
Motor mounting

The shorter screws that come with the motor is a "almost" perfect fit. With almost I'm saying it'll work in a few holes but in some holes the insulation of the motor lead (which extends into the motor for some reason) will create some problems. Thus, you need to have some M2 washers at hand.

I soldered the motor leads directly to the ESCs. I soldered them one at the time and check with a servo tester that the motor was spinning in the right direction. Essentially, the result is that the cables on the front right and back left mounts "straight" and the other two "crossed". The finished dirty plate looks as the picture below. Please note that I added the landing gears while building to simplify a little, I'll remove those later.

Dirty plate
Laser230 dirty plate.

Flight controller

I ordered a CC3D without any connectors soldered this time. This is much simpler and makes a much nicer build. It's easy to solder the cables you need and you can cut them to the proper length and not worry about clamping connectors on them.

I installed pins for two of the output ports. I intend on using one for a lost model alarm. I make a "special cable" with the connectors that comes with the controller board for connecting the SBUS output of the receiver into the main port. On the image below all ESC and receiver wires are in place.

Flight controller
Clean plate with flight controller installed and receiver connected.

FPV Camera

I ordered a 700TVL Sony-based board-cam for this build. I picked one with a little smaller board size than usuall to make sure it would fit, it measures 32x32mm. This particular one has a 2.1mm wide angle lens. I have no idea what it will be like since it's a bit wider than usual.

The mount and camera PCB are drilled with 2.5mm holes. This prevents me from using my stock of 3mm nylon to mount it. Not wanting to wait for a set of 2.5mm nylon screws and standoffs I got the advice to shave off the threads on the 3mm nylon to make them fit. It worked well and I melted down the threads to fix it in place. The melting went so-so.

Board cam attached to the camera mount.

The camera can be mounted on either side of the frame. On one side the camera mount is at the edge of the frame and on the other side it is mounted further inside the frame to protect the camera. But to avoid looking into the edges of the frame with the wide angle lens I went with the edge mounted side.

I intended to place the transmitter behind the camera but it turned out the propellers extend into the frame and would effectively cut the antennas. Thus, the placement on the image below was impossible.

Board camera mounted on the frame

The video transmitter

My previous build had a few issues concerning the video transmitter. The device was mounted flat with no access to the channel switches. The layout of the Immersion and Fatshark VTx's are a bit annoying. Additionally the antenna, a heavy and expensive Immersion/Fatshark one, was simply attached with a  elbow SMA adapter. The result of this was a broken off SMA connector on the video transmitter.

With this build I wanted to address those issues. I attached the video transmitter to the top plate of the frame. To get proper cooling of the device you should mount it with the metal case away from the surface, which places the channel switches against the surface. I simply align the switches with a hole in the plate. The transmitter is located in the center of the quad and a pigtail extension of the connector leads to the back end where it is screwed into a hole. This makes a stable antenna mount and should avoid any stress on the transmitter itself.

Video transmitter with pigtail connector

The noise filter

FPV setups sometimes suffers from noise from other electronic components like the ESC, BEC or servos. The noise causes disturbances in the image transmitted to the video receiver. I've experienced this once before and now I usually install a filter to prevent this issue.

This time I built a filter using a 100nF ceramic capacitory, 470uF electrolytic capacitor and a rather large inductor speced at 100uH. The components are mounted on a small piece of experimental board which at the same time acts as power distribution and connects the cables between the camera and the video transmitter. I also added a JST connector to be able to disconnect the entire FPV section of the system while flying without camera.

Flight controller and noise filter
Noise filter next to the flight controller

Final assembly

Last but not least I install the receiver. I had to replan the installation when I discovered that the propellers enter into the fuselage and would effectively cut the antennas. I had to move the receiver to the back. Unfortunately the antennas then exits the fuselage in the center instead of up front. I would have preferred to have them up front to avoid the proximity of the FPV transmitter antenna.

I also installed a buzzer to the 5th output of the CC3D. Some hacking with the mixes in the CC3D then allows me to control the buzzer with a switch on the radio. Instead I could have used one of the PWM outputs on the receiver.

Laser230 / Diatone 17# assembled

CC3D Configuration

I used the TxPID module this time to adjust the PID settings. I've only done the Attitude settings so far and it took me about 3 full batteries to get it right. As usual, the numbers are way off to start with. Here are my numbers. I think it flies well with this configuration but your results may not be the same!

Attitude mode CC3D PID configuration

Additional work required

  • CC3D rate mode setup
  • Camera test and adjustments

Flight results

The first FPV flight turned out well, no crashes. The machine handles well but I have the rates set too high and there's slight oscillations in certain situations. The wide angle lens feels weird to fly with. Flight data can be found in the flight log.

External links

Side notes

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