Futaba M6 Fr Sky 2.4 ghz DIY Conversion

[Paul Luby]

Hi guys

I tend to use RC Groups quite a bit, but given RCM&E's latest articles regards the Taranis transmitter and electronics modules, I thought I'd give the RCM&E forum a try.

I agree with statements made by quite a few guys regards some recent articles, its nice to see the E back in RCM&E.

I use to build my own radio gear, usually Micron but with the odd RCM&E Rx included.

I currently have a Spektrum DX 18 but Fr Sky with their Taranis has brought Electronics back into the hobby for me. I've had my Taranis for about 4 months now and can't fault it. So my DX 18 is resigned to use on my Bind & Fly stuff at the minute.

I'm into electronics and a little hobby programming, so my latest project is a little different and involves a 1972 Futaba M6, an Arduino Nano and a FrSky DIY module.

I've flown my electric Flair Magnatilla using it and it was just like the old days, no rates and long stick moments, lovely.

Anyhow, enjoyed the article about the Taranis Spektrum Module, hope you guys enjoy the pictures.

My next project involves an old Micron PL-7D transmitter and a Fr Sky DIY Module.

Paul

(AKA Veri-Gash)

[Chris Bott - Moderator]

Hi Paul and welcome to the forum.

It's great to see some electronics. I guess you already know how much I like the Taranis?

Nice coincidence here that now I have a good range of FrSky Rx's, I've been seriously considering adding an internal module to my old Waltron 4/5 transmitter.

I can't help but ask, what is the Arduino doing in the Futaba M6?

[Paul Luby]

Hi Chris

I got the Futaba M6 off an gent who restores old RC gear and then sells them on e-bay, unfortunately he can only undertake minor electronics repairs but nothing major. This one was beyond all hope with damaged tracks and missing components. I'd been looking to convert an old RC set to 2.4 ghz for a bit of a laugh and couldn't resist the old M6.

The original sticks and pots were all in great condition and the gent in question had even tracked down a suitable paint alternative that matched the original finish, you'd like his workshop, its like a vintage RC Museum.

So all I needed to do was replace the PPM encoding section and install the 2.4 module.

As I already have many Arduinos kicking around it was a fairly simple task to replace the Tx encoding section with an Arduino Nano that I programmed to generate the Pulse Proportional Modulation stream that the Fr Sky DIY module requires.

I used the Nano analogue to digital inputs to read the stick pot values, the Nano digital inputs to read the switch positions, applied a little programming magic to build a PPM stream, passed that to one of the Nano digital output pins, fed that to the Fr Sky DIY module and and bobs your uncle.

It has no extra model memories and is just a Tx that works with the Rx to which it is bound, just like the old days, but minus the frequency flags, pegs and crystals.

The elderly gents down my local club in Selby really like it, brings back my youth also.

A couple of mates in the Brize Norton RAFMAA Club have converted their Futaba FF Rc gear using the DIY module fed by the original encoding sections and they work really well. So if you can find your Waltron PPM stream its an easy mod, if not use an Arduino to generate the PPM stream.

Below is a picture of the original Futaba M6 PCB for comparison.

If I could work out how to include a .PDF into this message I'd post a copy of the Arduino code for you to look at.

Hope that answers some questions.

Nice Spektrum Module article in the Mag by the way. I stopped getting RCM&E cause of the lack of E. I just get Flying Scale Models at the minute cause that's my thing. If the amount of E increases I may have to reassess my subscriptions.

Paul

(AKA Veri-Gash)

Edited By Paul Luby on 13/04/2014 12:53:37

[Biggles' Elder Brother - Moderator]

Fantastic! What a wonderful marriage of the old and the new! Taranis/FrSky, Arduino and a Futaba M7! Who'd have thought it. I think its excellent that the new found freedom we are given by Taranis is inspiring people to rediscover experimenting with our R/C gear.

Well done - really interesting.

BEB

[Chris Bott - Moderator]

Many thanks Paul.

Sorry - only a .jpg can be attached here.

I haven't retrieved the Waltron from the loft yet, never mind looked for PPM. I seem to remember it having a buddy connection on the front, so that's where I'll start.

If I do end up needing an Arduino encoder, I know where to come for help

[Paul Luby]

Hi Guys

Many thanks for the nice words.

I think modern modelling has become a buy, fly and throw away hobby over the last few years, which is a great shame cause the modelling men in sheds I remember from my youth were a great bunch of guys.

If you do end up doing something similar by all means get in touch.

Paul

(AKA Veri-Gash)

[Former Member]

[This posting has been removed]

[Paul Luby]

Hi Guys

Seen as we can't post PDF's on this forum I've turned the Arduino code I wrote into a JPEG picture.

Hope this works as a picture.

Please feel free to copy, modify and use this code.

Paul

(AKA Veri-Gash)

Edited By Paul Luby on 13/04/2014 20:12:48

Edited By Paul Luby on 13/04/2014 20:13:00

Edited By Paul Luby on 13/04/2014 20:14:07

[DG3]

very cool! I was thinking of doing something similar to an old Fleet PCM MX7 and this project http://www.reseau.org/arduinorc/.

Out of interest do you have the trim pots working?

[GONZO]

If your interested in retro RC try **LINK**

and **LINK**

Conversions aplenty(including M series) in the first link and 2.4gHz single channel and reeds in the second.

HTH

[Chris Bott - Moderator]

Thanks very much for going to that effort Paul.

That could turn out very useful indeed.

[Phil Green]

>>down my local club in Selby ...

Selby North Yorkshire Paul? If so you're not far from me, will you be coming to the PANDAS S/C & Retro R/C event at Ponty, 8th June? Theres a lot of interest in resurrecting 1960/70/80 radios. Details on S/C website

Cheers

Phil

[Paul Luby]

Hi Guys

DG3

I've seen the project page at www.reseau.org/arduinorc/ before.

When I read it, it seemed vague about whether when you changed models you had to rebind. My guess is that you have to so I didn't bother going the multiple model and power off storage route.

So I've ended up with basically a 1970's Tx which is what I was aiming for.

Gonzo

Gonna take a while to read through all those, they do look interesting. I'm revising for an Open University Nano-Technolgy exam at the minute so reading through them all may have to wait. I'm also out of the RAF in 4 months after 30 years service so finding a job is up there on the priority list. I did have a quick look and noticed one guy that converted the Skyleader seemed to be using a PIC microcontroller.

Thanks for the links, it proves that those modelling man in sheds are still at it.

Chris

Hope the code picture helped.

I've made undercarriage sequencers, mixers, etc using Arduinos for club members.

But here's the link to my latest purchase.

http://www.element14.com/community/community/knode/single-board_computers/riotboard

Now that's power, how about a computer radio that is powered by Android. One minute your using it to programme a new model, next your watching a movie on it. I know the question is why would you and the answer is, because I can.

Even better, what about a radio that you plug your Android phone into. Your phone has an app that stores all your model data, mixes, rates, expo, etc. When you finish flying you unplug your phone. As a result all you model data is backed up on the Android cloud.

Must stop dreaming, I've a way to go yet before I can program that.

Phill

Might take a drive down and check it out, haven't got time to build a single channel model at the minute given pending exam and leaving the RAF, but wife permitting will take a drive down and check it out. Might bring a Futaba M6 set and an electric Magnatilla that I have lying around.

Paul

(AKA Veri-Gash)

[Phil Green]

Your Maggie and M6 would be very welcome Paul, its not exclusively single-channel, in fact most of the SAM35 lads use propo sets. See you there!

Cheers

Phil

PS the nano-tech stuff sounds fascinating!

[Paul Luby]

DG3

Sorry I didn't answer your question regards trim pots. Yes the trims are fully functional.

The trims on the Futaba M6 are mechanical. Essentially the stick moves the potentiometer shaft, while the trim lever mechanically moves the potentiometer around the shaft.

So there's only one potentiometer per axis for stick and trim.

If your doing a conversion where there is a stick pot and a trim pot per axis then all you have to do is use one Arduino internal analogue to digital converter (ADC) per pot and mix them in the programming.

This means that you need two ADC's per axis.

I did this on a Tx I made that utilised sticks from the new HiTec Aurora 9x which also had separate trim pots. Its just extra programming and a bit of math.

Easy.

But the Futaba M6 method is easier, as there's less programming.

Paul

(AKA Veri-Gash)

[DG3]

Thanks Paul. I am now really interested in converting my Fleet PCM MX7 and have stripped the old circuit boards out to start from scratch and learn more about arduino. In one of your photos the circuit board has diodes mounted on it - just wondering what the function is? Also, by any chance do you have code that includes the trim function? Cheers. I will post photos soon. D

[Phil Green]

Posted by Paul Luby on 13/04/2014 22:32:28:

...and noticed one guy that converted the Skyleader seemed to be using a PIC microcontroller.

Yep, that was me Paul. Its not a business or anything commercial, I'm just a bloke in a shed making a range of encoders including a true single channel emulation, 1+1 propo, 2+1, Codamac, 12-channel reeds, a tiny 6-channel reeds, pulse propo (for Adams magnetic actuators) and a 5-channel propo, and various other R/C gadgets and add-ons. All PIC assembler.

I love the old gear but I hate to see it 'collected', sitting in a cabinet somewhere. Especially if its awaiting the day 'it might be worth something' ! Much better to get them converted and back down the field where they belong!

My own converted trannies, all of which are flown regularly, include a Remcon 12 Reeds, an Orbit 10 Reeds, a Macgregor MR200 single-channel, a Macgregor Digimac 1+1, a Gem single-channel (seen in avatar), an RCS Guidance System single-channel, a Micron Elf S/C propo (very rare!), the Skyleader Clubman, my own Tiny-6 six-channel Reeds set, a tiny palm-sized 2ch propo set, and many others in various stages of assembly/gutting for parts/restoration!

I do hope you can make it to the Ponty bash, would be great to meet up. Details here.

Cheers

Phil

Edited By Phil Green on 19/04/2014 01:12:04

[Paul Luby]

Hi DG3

Heres the Arduino code I used for a Transmitter that has 4 stick pots and 4 trim pots. I wrote it so it also had 2 x 3 position switches and 2 x 2 position switches.

The Arduino Nano has 8 ADC's so in a Tx with the above configuration you will be using all 8 ADC's for primary control and will have none left for variable flaps, etc. Thats why I encoded it to include the 3 and 2 position switches.

If you need the ADC's for other uses then their are ways round it, but these depend upon pot value and involve adding resistors to the circuit.

Using a ADC input per pot is a more flexible way of doing it.

If you do it this way, using all 8 ADC's for the primary inputs and still need other channels to be variable them you can look at using and Arduino Mega which has 16 ADC's. If your restricted on space then you can look at and Arduino Nano Dreamer, it has 6 normally assigned ADC's and another 6 that are on digital pins that can be assigned as ADC's, giving you 12 ADC's to play with.

As for the Diodes. The Arduino Nano has an ideal input range of 7 to 12 Volts and the FrSky DIY module has an ideal input range of 6 to 13 Volts. I use a 3 cell LIPO in my projects which at 12.6 Volts when fully charged is above the Arduino Nano ideal limits. So I put 2 x 1N4001 forward biased diodes in series with the battery positive and this drops a fully charged 3 cell LIPO voltage to approx 11 Volts and a discharged 3 cell LIPO will be about 7.5 Volts. Both are well within the ideal ranges of both devices.

Hopes this helps.

Paul.

(AKA Veri-Gash)

 

 

Edited By Paul Luby on 19/04/2014 11:25:46

[Braddock, VC]

Posted by Paul Luby on 13/04/2014 22:32:28:

Hi Guys

I know the question is why would you and the answer is, because I can.

Paul

(AKA Veri-Gash)

Thanks, Paul. I often wondered what drove people to recommission all that old stuff and you've put me right!

I generally "do" vintage models and answered the same question "because I did". Must have been my Forrest Gump moment.

If I say you lost me three words into the technical jargon you'll understand that I could never be really involved in something like you do, pity really. C'est la vie.

[Phil Green]

Posted by Braddock, VC on 19/04/2014 12:38:35:

Thanks, Paul. I often wondered what drove people to recommission all that old stuff

We do it because its fun! because of the the reaction you get on the flightline when someone realises you're flying reeds or S/C or even a 1970s propo set! the reminiscences and banter it generates makes it all worthwhile... and theres a lot of pleasure to be had from flying an old model design on the gear it was originally intended for! If you fit modern propo into say a Sharkface, and fit an elevator, then not only are you missing the point entirely, you're denying yourself all the manic fun that style of model gives you flight after flight!

I do take your point that its not for everybody though BVC, each to his own

Heres my Kraft Series 71 refit:  http://www.modelflying.co.uk/forums/postings.asp?th=97589

Cheers

Phil

 

Edited By Phil Green on 11/07/2014 14:04:50

[Paul Luby]

Hi Braddock

My modelling history tends to involve models of early aviation types, though not vintage models. My models tend to be own designed or built from plan.

I'm a massive David Boddington fan as I cut my teeth so to speak on his plans. Below is a picture of my modified DB Bleriot XIb with which I took the Concours d'Elegance Trophy at the RAF Model Aircraft Association Model Champs a few years ago. It was destroyed by a NiMH fire a few years later.

Last year I bought my first ever ARTF, a Blackhorse 88 inch wingspan Wyvern, flew it and have spent the winter fitting decent retracts, etc to it. It'll probably be my last ARTF as I have my own way of designing and building a model, the way the Wyvern is built makes me cringe.

My next project is an own design Miles 20 fighter from WWII. Then I have a Balsa USA 1/3rd scale Morane Saulnier A1 kit and a beautifully kitted DB Sport & Scale 88 inch SE5a to build.

Regards the electronics, its not difficult and you'd be surprised how quickly you'd be able to get an old Tx up and running for that nostalgic experience. I love flying my old Flair Magnatilla using my 2.4 ghz modified Futaba M6 Tx.

In the old days you could buy a Tx & Rx kit from Terry Tippet at Micron and have a pretty good chance of producing a quality set of radio gear yourself. Nowadays its not so easy but the internet has made the process do-able because there's so much help out their.

I'm an aircraft electronics tech by trade so its my bag so to speak, but I've got aircraft mechs into building and upgrading their own gear and their pretty well hooked now.

I think I said in an earlier post, I'd love to see a lot more proper "E" in "RCM & E" in the hope that more guys will have a go at building their own gear again.

I wonder if we could come up with a "Homemade" logo for guys who make their own gear, or how about a "Putting the E back in RCM & E" logo for guys to put on their home modified and home made radio sets, just to differentiate down at the flying field between those that are bought and flown and those that are built and flown.

Hmmmm, "Putting the E back in RCM & E" sounds like the title for a set of electronics feature articles in the mag, what do you reckon Chris?

Paul

(AKA Veri-Gash)

Edited By Paul Luby on 19/04/2014 14:45:29

[Braddock, VC]

Paul If you knew me then you'd know that anything electronics and I don't gel. I'm a bit sad in that last year I threw out a futaba digimax tx together with half a dozen servos and two rxs and reading this could just as easily given them to someone to use. I also slung out a 7 (?) channel rcme tx together with an rx plus a 6 channel sanwa with a module plus several other old bits of r/c stuff.

Phil, everything I do nowadays is for fun but my needs are simplified by using store bought stuff.

I love putting together old vintage style planes and whilst I have assembled many artfs can quite easily do without them as nowadays my free time is limited as I'm supposed to be retired and whilst I have a couple of artfs in the loft (F1 pylon racers, my fantasy!) I have several kits to build and I enjoy building them, three flair, one sig and a global p51 which should keep me going til my toes turn up.

As I said in my earlier post I wondered why and now I have the answer.

I have a design in mind that I'd like to attempt and have been corresponding with the owner of the full size as it is one of a kind but my lack of skill with electronics is replicated in my constructional ability so it'll probably never see the light of day. Ho Hum.

[Braddock, VC]

PS Paul, forgot to say, Bleriot looks good .

[Paul Luby]

Hi Braddock

Ain't that the beauty of this hobby, there's so many so many areas it covers if you want to delve into them that you end up finding your niche.

What is the design your chatting with the owner about? Cause I reckon if you can put a Flair kit together you can make a very decent job of designing an aircraft structure that'll work.

If your unsure about having a bash at designing, have a look on RC Groups Forums, odds on someone has done or is looking at doing the aircraft in question and will be willing to help.

There's nothing like watching your own creation take to the air.

Check out the link below. If you remember the David Boddington Mascot from the 80's and 90's then check out my 140% enlarged one, I've called it the Mascot XL. Its a great flying model and if you can put a Flair kit together then you can design something like this. The structure is very different to the original, for example it has built up wing instead of foam as I like balsa bashing. I always have a Mascot of some size available to fly, the basic David Boddington design is that good.

Mascot XL Link

I bumped into the guy who used to draw up a lot of David Boddingtons plans at a model show. He drew up the original plans for the Mascot, I showed him my Mascot XL and he was quite emotional. As a moment, it was worth its weight in gold.

So please don't be put off designing your own, start by modifying the plan of a design you have built and flown successfully and see were it takes you. That's how I started designing my own 35 years ago, a larger Mascot, the design of which has got larger and larger over the years, and most of mine have now been own designs for over 30 years.

Thanks for the comment about the Bleriot. The picture below was how it looked after the NiMH fire. My wife said, "Its only a model", many deep breaths were taken at the time. But watching it fly given the plan was extensively different to the original DB plan was an incredible feeling.

Go on, have a bash.

Edited By Paul Luby on 19/04/2014 19:09:16

[DG3]

Hi Paul,

Thanks for the code that includes the trim function and for pointing out the diodes functioning to drop the voltage down. I am relatively new to Arduino and have only made an OpenXVario for my Taranis previously but that really was just following instructions. I have tinkered with LCD's, temperature sensors and driving LED's - basic stuff but all useful building blocks to learn with. I now have a great use for the Arduino in RC. Your code is easy to follow.

Attached photos are of my 1992 Fleet PCM MX7. I decided to strip out the old circuit boards and start from scratch like what you have done. I could have left them in and tried getting a PPM signal to the Frsky DHT DIY unit but this way is more interesting. At the moment I have wired up all sticks pots and trim pots using all 8 ADC inputs. Rate switches are wired to the digital inputs and I will do the same with some of the top mounted two position switches later. The on/off switch and battery meter are wired in and functional. This transmitter has two additional sliders and two top mounted pots for mixes that need ADC's. Thanks for the tip on the Arduino Nano Dreamer - I think this will be stage 2 of the project. I need to sit down now and calibrate the pot end points and check the programming while waiting on the DHT DIY to be delivered. An oscilloscope would be hand to visualise the ppm output stream.

I see you have used Arduinos for other RC purposes - am very interested in this. Have you posted any info about them anywhere I could look up? Cheers, D

To the other poster, Braddock - It is great to reuse old stuff. My old Fleet servos are over 20 years old and had to be rewired with standard JR type plugs before putting them in a Flair Puppeteer that I started building 20 years ago and only finished last year. As servos go they are old and slow but perfectly functional for this type of model. **LINK**