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Futaba M6 Fr Sky 2.4 ghz DIY Conversion

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Paul Luby13/04/2014 11:13:22
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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.

Futaba M6 front ps.jpg

futaba m6 side ps.jpg

futaba m6 top ps.jpg

futaba m6 inside ps.jpg

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

Paul

(AKA Veri-Gash)

Chris Bott - Moderator13/04/2014 12:00:29
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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 Luby13/04/2014 12:51:32
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126 forum posts
85 photos

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)

futabam6-1.jpg

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

Biggles' Elder Brother - Moderator13/04/2014 12:58:27
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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 - Moderator13/04/2014 13:00:35
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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 thumbs up

Paul Luby13/04/2014 13:16:13
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126 forum posts
85 photos

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)

Andrew Ray13/04/2014 19:00:25
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743 forum posts
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Now this is more like it thumbs up

I still have a Micron PL-6D (27Mhz) and PL-7D (35 Mhz), at least I think it's a 7D, it was my favourite transmitter for many years having simple rate on just two channels. I have been thinking that I might use the FrSky hack module.

I would be great to see more of these old sets recycled. Fantastic.

Paul Luby13/04/2014 20:12:23
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126 forum posts
85 photos

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.

futaba m6 arduino code.jpg

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

DG313/04/2014 20:29:13
75 forum posts
29 photos

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?

GONZO13/04/2014 20:38:57
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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 - Moderator13/04/2014 20:42:36
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Thanks very much for going to that effort Paul.

That could turn out very useful indeed.

Phil Green13/04/2014 22:14:38
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1542 forum posts
314 photos

>>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 Luby13/04/2014 22:32:28
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126 forum posts
85 photos

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 Green13/04/2014 22:40:40
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1542 forum posts
314 photos

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 Luby13/04/2014 23:38:58
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126 forum posts
85 photos

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)

DG318/04/2014 23:56:15
75 forum posts
29 photos

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 Green19/04/2014 01:08:34
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1542 forum posts
314 photos
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 Luby19/04/2014 11:24:17
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126 forum posts
85 photos

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)

 

 

tx 4a 4t 2d3 2d2 arduino nano code.jpg

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

Braddock, VC19/04/2014 12:38:35
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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 Green19/04/2014 13:47:47
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1542 forum posts
314 photos

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 smiley

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

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