Variophon conversion

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Mike_K
Posts: 669
Joined: 16 Feb 2018, 06:35
Location: Hertfordshire

Re: Variophon conversion

Post by Mike_K »

Hi Pete

I tried my Variophon conversion on a simulator using mode 1 sticks and it was just like I was a beginner again, flying bang-bang and mode 1 at the same time was just a step too far. I even struggled on the simulator with a 3 channel trainer unless I flew it more like a single channel, using just rudder and an occasional dab of elevator.

So I tried mode 2 and it did help a lot, but I couldn't then use aileron and elevator at the same time with the gates (hence why mode 1 came into being all those years ago). To stand a fighting chance I removed the gates and now I can happily fly the trainer around on the simulator, even though pulsing aileron/elevator at the same time doesn't come naturally.

I plan to test fly the Variophon using an old trainer, but to save crashing unnecessarily I had planed to use one of the Turnigy on-board receiver switches (a type of an on-board buddy box with two receivers in, one out) and have somebody on the master transmitter in case I mess up. But HK have been out of stock with all their on-board receiver switches for weeks, so I decided to build my own using an Arduino and that has delayed things a few days. I plan to test fly the on-board receiver switch this evening and if all is well will probably test fly the Variophon in the trainer over the weekend (assuming I can persuade Richard Ginger to take me on as a trainee).

I've given up with the Graupner Caravelle build for the moment as I realise I need a nice stable trainer until I get more adapt at flying the Variophon which won't be before Ponty.

It will be a busy test flying weekend as I've also got a Lil Toad with a Tobe GG actuator and Dubro mixer and my second Pulstar to test fly. Fun!

Cheers

Mike
Pchristy
Posts: 413
Joined: 16 Feb 2018, 13:57
Location: South Devon, UK

Re: Variophon conversion

Post by Pchristy »

Thanks for the update Mike! My Variophon was originally 4-channel - rudder and elevator on the right (non-simultaneous). When I bought the add on modules to expand it to 6-channel, I moved the elevator to the left. I never had a problem switching, but I was much younger back then! When I got my first proportional set, it was back to having elevator on the right, and again, I didn't have any issues. Having said all that, I wasn't flying "Hot" aerobatic machines back then!

The transmitter is now complete and has been "smoke tested" successfully! I had to rethink my installation a bit, though:

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Originally, I planned to put the encoder board in the empty right hand panel, mirroring the RF board, but it was just a fraction too wide! Instead, its gone under the aerial in the middle. This makes it more fiddly to plug and unplug things, but hopefully I won't need to do that often!

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I've never handled a 10-channel Variophon before (mine is only 8), but there was a hole in the rear casing with a DIN plug behind it for charging. I don't know if this was standard, or whether it was done by a previous owner, but I had intended to put the "speed" pot behind it. Unfortunately, having to move the encoder has scuppered that idea, so I've put it in the battery compartment, as Frank suggested (more drilling seriously thick steel!).

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At this point, I disconnected the RF board, and carries out a "smoke test" on the encoder, monitoring with a 'scope. Pulses appeared and appeared to move as expected, so next it was fire up the spectrum analyzer and check for RF output - YES! It was all there!

And here's the (almost) finished product:

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I need to find a grommet to fill the charge socket hole in the back, and make a decal to cover the bind button and LED a bit better. Also the case hasn't gone back together quite as accurately as I would have liked - maybe theres a wire trapped somewhere, though I was pretty careful. Either way, I'd better open it up again and check, but that's a job for tomorrow!

Hopefully I'll get to test the Jackdaw over the week-end. Once its trimmed using a propo Tx, I'll start practicing with the Grundig. Need to get my hand in before Ponty...... ;)

--
Pete
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tiptipflyer
Posts: 393
Joined: 16 Feb 2018, 22:49
Location: Germany

Re: Variophon conversion

Post by tiptipflyer »

Pete, why not using a DIN-plug again as a charging jack for your batterie, you can even connect all ballancing wires to that plug for a full ballanced charge. I do that in some of my transmitters.
That charging plug was standard in the later series of Variophon tranies. The early models didn´t have it.

Frank
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Shaun
Posts: 1048
Joined: 15 Feb 2018, 21:49
Location: West Yorkshire

Re: Variophon conversion

Post by Shaun »

I do prefer the joystick type reed sets. As I couldn't find a suitable Tx to convert at the time( for sensible money) I used an FM retro radio Sainsburys had on offer for £15.00 and ripped out the guts. In fact it could qualify as a vintage set now as it used one of Phils early hand etched PCB's for the 10 channel reed encoder. :lol:

The micro switch stick units are superb and very well engineered, from memory only about £12.00 each.

I initially used a Corona Rf module but later converted it to Spektrum

Shaun
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Pchristy
Posts: 413
Joined: 16 Feb 2018, 13:57
Location: South Devon, UK

Re: Variophon conversion

Post by Pchristy »

Frank: I'll be using a 2S LiPo for power, and I don't like charging those in situ for safety reasons. I don't like using LiPos in transmitters, but I'm not convinced a 2S LiFe would have enough headroom for the voltage regulators.

Shaun: Yes, I remember your faux Metz! Where did you get those switches from? I ought to get a set to play with.... :)

Beautiful weather at the moment, and I'm stuck in the house waiting (and waiting and waiting) for the insurer's plumber to come and fix the drainage issue in the kitchen. Grrrr!

--
Pete
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Mike_K
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Joined: 16 Feb 2018, 06:35
Location: Hertfordshire

Re: Variophon conversion

Post by Mike_K »

Pete

In my experience a 2S LiFe is more than adequate for either a FrSky or OrangeRx hack modules and an Arduino as well. Both the FrSky and OrangeRx are rated for 6V minimum, use LDO or switched regulators and all their circuitry is 3V3 so plenty of headroom. And every Arduino I've tested has happily worked to well below 5V on the Vin pin. They also use LDO regulators, so at 5V have around 4.3V going to the ATmega328 and the data sheet has the minimum voltage as 4.2V @ 16MHz (from memory), so you are within specs.

The minimum for a 2S LiFe is 5V, but similar to a lipo, you don't really want to go to the minimum, so 6V minimum is sensible. Therefore it seems a good match to me and it is what I've used in a few 2.4GHz conversions without problem. I charge them in-situ via the balance lead and a 6-pin DIN 5/180°connector that I don't use for any other application and also have a dedicated charger for LiFe batteries with the same connector (I use a different 6 pin DIN for Lipo's so I can't accidentally charge the wrong type).

The downside of LiFe batteries is that they don't come in nearly as many shapes and sizes as Lipo's, so if space is tight then they aren't always an option.

Cheers

Mike

ps some of my other Variophons have the DIN connector fitted in the same place as your's, so I think it may have been fitted in the factory. But then again, I got 7 of them from the same person (selling his late Fathers estate), so it may have been a personal modification. Maybe Frank knows if they came from the factory with DIN connectors?
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tiptipflyer
Posts: 393
Joined: 16 Feb 2018, 22:49
Location: Germany

Re: Variophon conversion

Post by tiptipflyer »

Yes, they came from the factory with the charging plug, but only the later models. The early models did not have it. I have five of them, one 4channel, one 8channel and three 10channel sets. Only one of the 10channel sets is equipped with the mentioned charging plug and its the newest one I have.
But it´s not a DIN charging plug as we know them now, it was a special Grundig version of it. The oulines are exactly as the modern DIN plugs, but the pins are a little different. Since the oulines are the same, you can easily replace them by a modern 5 or 7 pin DIN plug for ballance charging.
BTW its the same charging plug as the later Grundig TX14 and all the Varioprop propo sets had, so it was factory installed for sure.

Frank
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Shaun
Posts: 1048
Joined: 15 Feb 2018, 21:49
Location: West Yorkshire

Re: Variophon conversion

Post by Shaun »

Hi Pete,
I seem to remember getting the switch units from Farnell. They are excellent quality and have a great feel, just enough resistance but not like car window switches .

Shaun
jackdaw
Posts: 165
Joined: 16 Feb 2018, 20:30
Location: Wet and Windy North Wales

Re: Variophon conversion

Post by jackdaw »

Pchristy
Posts: 413
Joined: 16 Feb 2018, 13:57
Location: South Devon, UK

Re: Variophon conversion

Post by Pchristy »

Thanks all for the comments and info! The Tx is now complete - except for some minor cosmetic work - and the battery installed (a 2S LiPo).

Mike_K: thanks for the info on the regulators. I know LiFes normally sit around 6.6V on load, which *should* be enough headroom, but I wasn't sure. I do use 2S packs for some receiver installations, and 3S packs in 9.8V transmitters.

We've had a plumbing emergency going on for about a week now, and the insurance company and their contractors have been making matters worse rather than better, so my brother-in-law (a professional builder) is giving me a hand to sort it ourselves. Just as the good weather arrives! Great! By the time we have it fixed it will be back to wind and rain, no doubt.... :evil:

Still hoping to have it all sorted in time to get practiced for Ponty, though.....

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Pete
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