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Posted by JNJO | Jan 27, 2016 @ 05:05 PM | 5,247 Views
For use with either openXsensor or grmis $5-solution.
For the optical part, I ended up using a photo transistor.

The one I used is this:

This will only work well in daylight, but that's all I'm interested in.

I suggest using a 10-20 kOhm potentiometer to determine a good resistor value.

The signal line will go high when the phototransistor is blocked from light.

Signal goes to Promini pin D8 with openXsensor.
Signal goes to Promini pin D4 with grmis code.

Schematic below:

Posted by JNJO | Jul 26, 2015 @ 09:48 AM | 7,596 Views
Courtesy of Randy and VENKATAKRISHNAN M in this discussion: , I built an Arduino-based Tacho for brushless motors, primarily for use in a future motor test bench.
Please note that it is not intended as a high accuracy test equipment, but will be close to actual RPM:s
It does correspond well to my optical tacho.

I modified Randy's original code slightly:
- Added variable for number of poles
- Changed calculation of RPM to display non-truncated value.
- Commented out all but rpm serial output.

Edit this line to reflect the number of magnets in the motor to be run:
float numpoles = 14; //Change value to the number of magnets in the motor

Upload the code to the Promini, and leave it connected to the computer

Connect everything according to the diagram, noting the reversed colours of the power supply to the RPM-sensor.

Set your preferred serial monitor to 115kbaud.

Start the motor and you should see fairly accurate RPM readings in the serial monitor.

Posted by JNJO | Sep 23, 2014 @ 03:36 AM | 7,607 Views
Based on article in SMFF magazine "Modellflygnytt" issue 4/2014

Shoppinglist for 10 units:

10pcs. Arduino ProMini 20USD (or Nano)

2M servo cable + connectors: 3,25USD

10pcs. Buzzer: 4,54USD

Servo in/out - Promini D5
Buzzer+ - Promini D4
Alarmtrig: <1000us (Can be modified in the code to suit your needs.)


Wiring diagram:
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Posted by JNJO | Sep 07, 2014 @ 03:24 PM | 8,077 Views
I'm really not very good at combining tile-printed plans for scratch-builds.

I'm fortunate enough to have access to a printer for large sizes, but I don't want to print a whole new plan when I just need one template to replace a broken part or badly cut piece.
For the awesome FT-Viggen plans, made by David Windestål (, I cut out all parts except the tail ridge, the wing and the large fuselage part.
Those were scanned to a more accessible and manageable paper size.

All except two are size A3, the last two are A4.
Not a work of beauty, but they are 1:1 true in scale to the original plans.

I hope somebody finds them useful.
Posted by JNJO | Sep 06, 2014 @ 04:37 PM | 8,209 Views
My way of solving it.

Built using plans by Johan Hansson, downloaded from FliteTest
Johans original build thread is here: Sportskala Viggen EDF
There are plenty of good build logs already made for this awesome model, so I won't go into much detail.
I'm only showing how I got around what, for me, was the more critical steps.

My biggest concern was getting the formers done.
A tip from D_Fast on the SAAB Viggen thread suggested using cardboard.
Mine are made from empty Xerox printer paper boxes, which are about 2mm cardboard.
A well made pizza-box would probably work too.

Made some A3 and A4 size printouts for the formers to help with printing.

I make a rough outline with a dremel and a 2mm diamond wheel point.

Then, with a very light hand, sand down to the lines using a 6,4 mandrel.

Final sanding to get a smooth edge is done with 400 - 600 grit paper.
That is also used to get rid of the "paper-frizz" around the edges.

I make two formers for each station, one for the inner cut, one for the outer.
They are dirt cheap and quick to make, and I like the extra stability.
I make a centerline on each former to aid in placement.
...Continue Reading
Posted by JNJO | Aug 16, 2014 @ 01:46 PM | 12,615 Views
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En cellplast-Delta är syndigt rolig att flyga, enkel och billig att bygga, och i princip (nästan) oförstörbar.
Då det väl går sönder något är det busenkelt att reparera, eller så bygger man helt enkelt en ny.

All ära för konstruktionen av denna lysande all-round modell går till IBM-klubbens designavdelning med Stene i spetsen.

Här följer en beskrivning på hur jag bygger mina.
Jag börjar med att bygga den i sin enklaste form, för att därefter visa de extra steg jag använder mig av.

Om du aldrig handlat på HobbyKing bör du veta att det förvisso är riktigt billigt, men leveranstiderna med vanlig post kan vara mycket långa (>20 dagar), dokumentationen är vanligen undermålig, kundsupporten obefintlig och garantin är i princip oanvändbar. (Ändå handlar jag rätt mycket där.)
Numera kan man välja DHL för snabbleverans, men priset blir därefter.
SCS och EMS express är i min mening värdelösa som leveransalternativ från HobbyKing.
De har även ett lager i Europa som det går att beställa från. Något högre priser och leveranstider på 7-10 dagar med vanlig post.

Vill du ha snabb leverans och bra support finns ett flertal bra butiker i Sverige. Jag har bara gott att säga om Autopartner, Rynos och RCFlight.

Krav på radiostyrning:
  • Minst 4-kanal sändare och mottagare.
  • Måste klara elevon-mix, även känd som Delta-mix. (Det går faktiskt utan, men då behöver du en V-Tail Mixer.)
  • Möjlighet till expo är väldigt bra, men inte ett absolut krav.

Elektronik som behövs:
  • 3st. billiga servon. Ex.
...Continue Reading
Posted by JNJO | Jan 06, 2014 @ 12:29 PM | 11,274 Views
Pics of my Multiplex Twinstar II build.
Weighs in at initial AUW with 4S-3000mAh and all hardware, except camera and pan/tilt installed: 1530g.
(I expected it to be heavier.)

Motors: RCTimer HP2812-1000KV
Props,: APC 9x5 left and right rotation.
Lipo: Zippy 4s3000mAh/20C.
Current [email protected]% throttle, level flight: 5A
ESC: HK Blue 20A.
Flightcontrol: RCTimer Arduflyer 2.5.2, external mag, Firmware: APM:Plane 3.0.2
GPS: uBlox CN-06v2
Airspeed sensor: RCTimer.
C&V-sensor: RCTimer.
Telemetry: 433MHz RCTimer.
Main retracts: Turnigy MCR with 136mm oleos
Nose retract: HK steerable Replaced by the one included with main retracts.
LED-strips: HK Red, Green, Blue.
LED-control: HK Brushed ESC.
Landing lights: HK 3 LED strip.
Landing light switch: Turnigy Receiver Controlled Switch

Retract Video:
Multiplex Twinstar 2 Retract Demo (1 min 1 sec)
...Continue Reading
Posted by JNJO | Nov 11, 2013 @ 04:27 PM | 18,175 Views
This is the way I set up my system to run ArduPlane HIL (Hardware In Loop) on the X-Plane 10 flight simulator.

The official Wiki is here ->

Hardware that I use:
- RCTimer ArduFlyer 2.5.2
- Spektrum AR600 reciever
- Turnigy 9XR transmitter with Orange DSM2 module
- Dell Precision M4600 with 64-bit Windows 7 Ultimate.

Software that I use:
- X-Plane 10 retail. The free Demo version can be used to test that it works, before buying the full version.
The Demo stops accepting joystick inputs, and puts a splash screen on the main window after 10 minutes, but funnily enough, the APM still have control.
- ArduPlane 2.76 HIL firmware
- Mission Planner 1.2.84 build 1.1.5044.12328.

You will need to change firmware on your APM.
If you are using an APM in a flying model for this, save your parameters first for an easy roll-back to flight configuration.

1. Upload the HIL simulator firmware to the APM2.5 using Mission Planner.

2. Reset the APM to defaults by using MP terminal - setup - reset, and reboot the APM with the reset button on the board.

3. Connect a reciever to the APM. It will be powered from the APM, so there is no need for a battery to it.
I use 6 channels PWM, but PPM should also work. (Tested with a PPM Rx, and it works just fine)

4. Switch on your Radio TX, and calibrate radio in Mission Planner.
Radio calibration only seems to work when Sim-Link is running.

4. Install X-Plane 10, and...Continue Reading
Posted by JNJO | Jul 12, 2013 @ 04:13 AM | 15,486 Views
A diagram on how to connect the MinimOSD to the APM2.5 S0 port, and parameter changes needed for it to work.
This is a way to get the MinimOSD to recieve data from the APM, without having to connect to Mission Planner, or placing a switch between telemetry radio and MinimOSD, when using the regular telemetry port.

Although I have drawn straight cables, I recommend that you put a connector somewhere in between for easier maintenance.
You also want to keep the pins on the MinimOSD input for connecting your FTDI-cable to do configuration and updates of the MinimOSD.
Never connect the FTDI-cable to the MinimOSD when the APM is also connected.
I didn't include the camera, vTX or 12V-power as that will depend heavily on your setup, but how you connect those have no impact on this mod.

The MinimOSD I used for this diagram is the 3DR-version. If you have another MinimOSD, pay close attention to the signal names printed on the MinimOSD.
Regardless of which OSD you are using the connection should always be:
APM RX - OSD TX (You might not need this connected. See edits below.)

Next, change the parameters in Mission Planner - Adv. Parameter List for SR0 as shown in the other pic.

After you are done, the MinimOSD will always initialize, and recieve data from the APM. It does not matter if you have telemetry or not.

As with all changes and modification of the hardware,
check, double-check and check again, until it...Continue Reading