Variophon conversion

[F2B]

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.

This one?

[tiptipflyer]

No, it looks like this, it is a varioprop 12 transmitter, but the plug is the same.
But a lot people changed it to a standard DIN plug, because they don´t have the matching Grundig connector.

SAM_3314.JPG (39.95 KiB) Viewed 17546 times

Frank

[Pchristy]

Finally flew the "Jackdaw" with the Variophon today. Two flights, both successful, but sorry - no video! My cameraman was helping with the model!

Because I haven't flown "reeds" for sometime, and the set-up is "mode 1"(I usually fly "mode 2" with propo), I wanted it to be at full throttle before being released.

Take-offs were both a bit hairy, but it got away safely both times, and landings were fine. However, I think I will have to switch the Tx to "mode 2".

This isn't because I had a problem flying it "mode 1", but because it has a pronounced swing to the right when the tail comes up. The stick cannot be moved diagonally, so I have to make a choice between keeping it straight, or lifting off! On the other hand, once airborne, it is rarely necessary to apply aileron and elevator together - and it turns quicker on rudder, should a quick correction be needed on landing. So I'm inclined to put aileron and elevator on the right, and rudder and throttle on the left - simply to make the take-offs easier!

The swing to the right appears to be caused by the prop catching in the grass - there's not much ground clearance once the tail comes up.

I did need to slow the servos a fraction after the first flight, as it was definitely possible to see the "pulsing"! I didn't have to slow them much, and the second flight was much smoother, though again, the take-off was untidy, due to the rudder-or-elevator conflict.

All good fun, and much enjoyed by those present! Roll on Ponty........!



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Pete

[Shaun]

Looking forward to seeing it in action at Pontefract Pete. I did the same thing with my Gigametz tx and made it mode 2 on the sticks. Much easier to fly with.

Shaun

[Mike_K]

Hi Pete

I finally got round to test flying my Variophon last Friday afternoon in my old Junior 60 and it all went well. I know it is a bit of a cop-out using a Junior 60 that I can fly itself if needed, the couple of times when I messed up on the joysticks, I let it go and it sorted itself out fairly quickly, who needs electronic stabilisation?!

I reverted back to using the joystick gates as I found it difficult to pulse rudder and elevator together on the same stick. But there are times when you want both rudder and elevator at the same time, so I cheated a bit and have mixed the aileron stick (used for rudder) and the rudder stick together on the transmitter, so I can use either. At times I found it easier to use the right hand stick for elevator and the left hand stick for rudder so I could use both simultaneously. This comes quite naturally as I regularly use the left stick for rudder (on 4 channel models) for things like taking off, landing, and my occasional dabble with helicopters.

One quick question, how have you wired up your trim switches? With a normal reeds set you physically can't move the trim switch up and down at the same time, but with separate trim push buttons you can press them together. This shorts out the 5V from the Arduino and stops everything! I'm seriously thinking of wiring them in parallel and putting them on the single trim input. Or I might feed the trim switches 5V through a 200R resistor, so you'd never get a dead short.

As for the conversion, I made life difficult for myself by using a standard Nano. As you found, the new Arduinos with headers won't fit in the Variophon frame. I'd already cut some strip board to mount my 2.4 module on and thought I'd just cut some more strip board and knock up my own. So as I was making my own, I put the 10K resistors, the travel volume (header pins), the sounder and the speed pot on the board and fitted headers for the joysticks, so I could test it before fitting.

I didn't want to drill the case for the bind switch and LED so I have hid mine under the xtal cover. And I've powered it using a small 500mAh 2S lipo that I've fixed to the frame with velcro.

See you at Ponty

Mike

Graupner Variophon converted to 2.4

The internal layout of the Variophon

The bind plug hidden under the Xtal cover

[Pchristy]

Hi Mike,

Yes, its awkward having to decide which is more important - simultaneous Aileron and Elevator or Rudder and Elevator! The Jackdaw has a pronounced swing to the right as the tail comes up, and this made take-offs bit hairy with a "mode 1" setup. I've switched it back to "mode 2" now but haven't had chance to try it yet - and probably won't before Ponty!

Regarding the trim switches, I've only used one - "10" - for trim."9" has become a single-channel emulation button! (OK, left handed, but hey! Its only a button!) This has the advantage of making trim available on the other functions beside elevator. OK, not strictly period, but anything that helps is welcome!

Regarding the problem of pressing both buttons together, I would have thought you could use quite high value resistors as protection. Surely the Arduino inputs are high impedance, so you should be able to use (say) 4.7K resistors as protection, without problems. You may need to add a line of code to ignore the trim if both buttons are pressed together.

Good idea putting the bind button in the crystal slot! However, a bit awkward for routine range checks. I've put mine on the top, mirroring the trim buttons:





It was a tight squeeze, getting the standard FrSky bind board under the top plate, but it just fits!

BTW, if you need a replacement neckstrap, a Ukulele strap makes a perfect substitute:



And thank you to my glamorous model for her assistance in the photo.......



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Pete

[tiptipflyer]

Hey guys, if you cannot decide whether to use simulatanious rudder/elevator or aileron/elevator, here is my solution to the problem: build yourself a second (or even a third) transmitter.
I have transmitters for all kind of combinations, so I just have to remember, which one to take with me. Sometimes I got the wrong one.

Frank

[Pchristy]

That's great, Frank, but I'm actually a bit worried about flying the Variophon in "mode 2"! Although I fly propo mode 2, most of my Variophon flying back in the day was done in "mode 1", as I didn't have ailerons! So my instincts are programmed to fly "mode 1" with the Variophon!

I'm sure I'll be OK with "mode 2" - luckily you don't need to use the elevators that much on the Jackdaw - but I won't know until I try it.

If I had two Variophons in different modes, I think I'd get very confused, very quickly!!!

And its taken me long enough to locate (thanks, Mike!) and modify one!



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Pete

[Mosfets]

Nice conversion, look forward to seeing it in action.

Ade

[stuart mackay]

Another one now broadcasting on 2.4 GHz band. Thanks to Phil for the Reeduino and to all who have posted here for inspiration!