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2.4GHz Single-channel

Old 05-18-2010, 01:55 AM
  #1  
JMP_blackfoot
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Default 2.4GHz Single-channel

With the advent of the cheap 2.4GHz transmitters and receivers from China, it has become possible again to make one's own custom R/C systems.
I have just completed a 2.4GHz single channel system using the RF PCB from a FlySky/Hobbyking 4-channel transmitter and the corresponding receiver (The set sells for $29.99).
In the model goes the battery, receiver and one regular servo.
The simple coder based on a PIC 12F508 simulates the operation of a compound escapement (rubber or motorised).
Herewith two pictures of my transmitter. The case is made of 1/16" plywood and the power supply is a 4.8V, 800 mAh Eneloop flight pack.
The total drain of the transmitter is about 150 mA, the operation time between charges is about 5 hours.
If anybody is further interested, I can supply more details, schematics and the hex file to program the PIC with.
A video of the resulting operation is posted here:
http://dl.dropbox.com/u/2859003/Anim_Mono.avi
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Old 05-18-2010, 03:47 AM
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Default RE: 2.4GHz Single-channel

Nice work! ...Gene
Old 05-18-2010, 04:52 AM
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iflyj3
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Default RE: 2.4GHz Single-channel

Neat conversion.
Old 05-18-2010, 06:13 AM
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JMP_blackfoot
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Default RE: 2.4GHz Single-channel

Dan,

For your info, the FlySky RF PCB works down to two channels (3 pulses per frame) and 3.4 ms synch pause.
Correspondingly, the little transmitter sends a 6.4 ms PPM frame, to minimize the response time.
However, the receiver still outputs 6 channels at 20ms intervals (older receiver: 18 ms), the last 4 channels being fixed 1.5 ms.
I have asked FrSky what the minimum requirements are for their DIY module.
Old 05-18-2010, 02:25 PM
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iflyj3
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Default RE: 2.4GHz Single-channel

Thanks for the info JM.

I used the same transmitter deck you have and I found out something interesting. The receive antenna is on the PCB while the transmit antenna is the one that is external to the transmitter. I put the deck in a metal box and therefore reduced its ability to detect other transmitters being on. This could be a potiential problem in a crowded environment.

I initially wanted to use parts of this system because of the inexpensive recievers. However, now that XPS has released a 4 gram receiver, postage stamp size for $30, that takes care of my problem.
Old 05-18-2010, 02:54 PM
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Default RE: 2.4GHz Single-channel

ORIGINAL: iflyj3
I used the same transmitter deck you have and I found out something interesting. The receive antenna is on the PCB while the transmit antenna is the one that is external to the transmitter. I put the deck in a metal box and therefore reduced its ability to detect other transmitters being on. This could be a potiential problem in a crowded environment.
Exactly why this one is in a plywood box!
Anyway, I will switch to FrSky (and their $19.99, 3.5 gram 4-channel receiver) as soon as I ascertain the minimum PPM frame requirements.
Old 05-18-2010, 03:15 PM
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Default RE: 2.4GHz Single-channel

Interesting on the FrSky. I have been following them for the telemetry ability which they are supposed to release soon.
Old 05-20-2010, 05:58 AM
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JMP_blackfoot
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Default RE: 2.4GHz Single-channel

Just got this info from FrSky's Jonathan regarding the PPM frame requirements for the FrSky DIY module:
"Below is our engineers' comments for your questions.
a) The minimum acceptable number of channels is 3, and the sync-pause time is 4ms or more."

Old 05-20-2010, 08:46 AM
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Default RE: 2.4GHz Single-channel

Thanks for the info. On the basic encoders I have done, I send four channels anyway, regardless of the number used.
Old 05-21-2010, 02:37 AM
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JMP_blackfoot
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Default RE: 2.4GHz Single-channel

This Thursday the weather was perfect for the maiden flight of my Dave Platt rudder-only Halftone.
The model flew straight off-the-board, first controlled with a FlySky FS-CT6A transmitter in the conventional proportional mode.
After two flights to get the feel, my single-channel button transmitter was bound to the model's receiver and several more flights were made in the pushbutton one-press-and-hold-for-right , two-presses-and-hold-for left mode.
All very satisfying, with the particularly nice touch that nothing has to be modified in the model to switch between the two modes.
All it takes is to bind the model's receiver to the chosen transmitter.
I can't wait for the next fair weather day[8D]
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Old 05-21-2010, 05:32 AM
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Default RE: 2.4GHz Single-channel

Congratulations on the successful flights.

JMP, send me pictures of the Halftone directly and I will put them on the VRCS photobucket site. For those who have not see it go to http://photobucket.com/VRCS
Old 05-21-2010, 06:37 AM
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JMP_blackfoot
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Default RE: 2.4GHz Single-channel

Dan,

Pictures have been sent.
I was thinking that this system can easily be expanded to REM with two or three servos, still with complete proportional compatibility.
With the price of old sets on the auction site, could it be called Poor man's vintage radio?
About the FrSky DIY module, it doesn't work on 4 cells. Mine won't start up below 5.6V.
I think it needs 6 cells or two Lipo or A123 to be safe.
On the other hand, drain is only around 50 mA.
15 hour operating time with AAA Eneloops!
Old 05-21-2010, 07:14 AM
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Default RE: 2.4GHz Single-channel

You are correct. Visit my site at http://photobucket.com/StoneAgeRC and look at the conversions I have done. The FP-T3S is using the FlySky deck. It has since been changed out for an XPS deck because of the receive antenna being on the board and inside a metal case.

The encoder is three channel (sends four) and will handle either a pot or switches for throttle. It is programmable for servo travel and modulation direction. Also does V-tail. It uses a 16F684. Handles 8 different planes. There is room for more but I figured 8 was enough.
Old 05-25-2010, 10:52 AM
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Default RE: 2.4GHz Single-channel

Hi JMP,
Your post on the single channel half tone has promted me to reply.
I built a Half Tone back in the 60s when I was young and hade no sense. It had a very unreliable radio and was painted in several coats of enamel paint, I can't remember how many pounds it weighed but it was far to many. The upshot of all that was that if the aeroplane workede the radio did'nt and vice versa. I only remember two flights, the first after the initial climb out, I got it into a pilot induced oscilation( I managed this with only a single button remember) above a tall elm tree. It then dived vertically through said tree shedding pieces as it went. The second, started out much the same way except when I pressed the button nothing happened. I did'nt find it again for about two weeks. Stuck in a hedge, minus the wings and with the fus half full of water. You would'nt know where I could get a set of plans for it do you. Cheers Rob.
Old 05-25-2010, 03:45 PM
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JMP_blackfoot
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Default RE: 2.4GHz Single-channel

ORIGINAL: singlechannel
....You would'nt know where I could get a set of plans for it do you. Cheers Rob.
I built mine from copies of the article in Model Aircraft, which you'll find attached here.
For scaling it up, just remember that the span is 38 inches and the distance between wing ribs is 2.5 inches.
Built as per plan, but with a modern radio (FlySky 2.4 GHz 6-channel receiver, 800 mAh AAA Sanyo Eneloop pack and 15 gram servo), I obtain a weight of 15.5 ounces which is 4.5 ounces lighter than the original. The model flew right off the board on a calm day and needs only 1 mm packing at the tailplane T.E. on windy days.
The ancient Baby Bee with an old Top Flite nylon 6x3 prop is almost too much power at that weight.
Covering is printer laminating film (like Doculam or the 15 mil film here:
http://www.oregonlam.com/thermrf1.htm#1512500 ), over which I doped tissue paper.
The tissue is applied wet and doped through. Of course, this first coat of dope blushes, but the blush disappears with the second coat.
I found that adhesion of the tissue is improved if the film is first sanded lightly with 800 paper then washed with white vinegar to prepare the surface.
The black trim is also paper doped over the tissue. Engine cowl is retained by two magnets, very convenient!
Happy flying.

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Old 05-25-2010, 11:23 PM
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Default RE: 2.4GHz Single-channel

The Executor is another Platt design worth considering. I've flown this one for several years with an OS 19 and a variety of vintage radios.
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Old 05-25-2010, 11:25 PM
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Default RE: 2.4GHz Single-channel

Article
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Old 05-26-2010, 08:07 AM
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Default RE: 2.4GHz Single-channel

I'll vouch for JMP blackfoot's tissue over Doculam finish. It has a vintage appearance and his Halftone looks great flying overhead with the sun shining through the covering.

Tom
Old 05-26-2010, 02:02 PM
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iflyj3
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Default RE: 2.4GHz Single-channel

If it is OK, as soon as I change to a new ISP I will put the mag article and your Executor picture on the Vintage picture site at http://photobucket.com/VRCS

For proper credit is this Ron Ellis?
Old 05-26-2010, 10:08 PM
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Default RE: 2.4GHz Single-channel

That's me, Dan.
Old 05-27-2010, 04:21 PM
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JMP_blackfoot
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Default RE: 2.4GHz Single-channel

Here is a tiled full-size plan for the Halftone. Just change the extension back to .zip instead of .txt
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Lj23831.txt (1.09 MB, 124 views)
Old 05-28-2010, 06:13 AM
  #22  
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Default RE: 2.4GHz Single-channel

Quite unaware of your project, I've been doing a very similar thing, mine emulates either sequential (like the Elmic Conquest) or compound (like the Elmic Commander) and also the quick-blip throttle and kick-up elevator. I'm currently working on reeds emulation (easy after the escapment emu's!) and Galloping Ghost.
Here's mine: [link=http://www.rcmf.co.uk/4um/index.php/topic,67157.msg758384.html#msg758384][LINK][/link]
Cheers
Phil
Old 05-28-2010, 08:56 AM
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Default RE: 2.4GHz Single-channel

ORIGINAL: phil_g

Quite unaware of your project, I've been doing a very similar thing, mine emulates either sequential (like the Elmic Conquest) or compound (like the Elmic Commander) and also the quick-blip throttle and kick-up elevator. I'm currently working on reeds emulation (easy after the escapment emu's!) and Galloping Ghost.
Here's mine: [link=http://www.rcmf.co.uk/4um/index.php/topic,67157.msg758384.html#msg758384][LINK][/link]
Cheers
Phil
Phil_g

Grotto2 has already done synthesized reeds, some years ago.

I have done a new 2.4 Ghz Galloping Ghost using 2 PIC processors and a home made actuator with no springs. It operates Rudder, elevator and throttle just like the original Ghost.
In the next couple of weeks I can post some pictures and description of that effort if anyone is interested. I can't do it now because of ISP limitations and I will be changing probably next week.
Old 05-28-2010, 11:27 PM
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Default RE: 2.4GHz Single-channel

ORIGINAL: phil_g
Quite unaware of your project, I've been doing a very similar thing...
Hi Phil, now we are both aware
We are going with the same thing indeed, with the processing of the button pulses in the transmitter and a normal servo installation in the model.
This indeed allows for test flying the model with a normal propo transmitter, which a big plus as "2.4G Shaun" said in the RCMF forum.
I see that you went all the way to simulate the operation of escapements, including cycling for every command and even the ratcheting noise.
The result is quite convincing, I must say.
Because I hope to fly stunts with my rudder-only models, I went for the fastest operation, which meant no cycling, instead going directly to the desired position. When pressing twice and hold, the servo in my version of the system goes directly to left.
I used two delays to accomplish this:
When press and hold for right rudder, the servo does not start to move until the button has been held for 0.12 s.
If the button is released before 0.12 s., the servo does not move until the button is pressed again. If the "off" time was less than 0.3 s., the servo moves to left immediately. If over 0.3 s., we're back to initial conditions.
The timings were chosen after filming my finger pressing the button and checking the times with a video editing software.
I have not included elevator kick-up or quick-blip yet, but will later when I build a bigger model with throttle.
I see that you change modes by holding the button down while switching the transmitter "on". I used this procedure to activate the bind mode instead, and intend to switch modes with internal jumpers (I think that adding a third mode of just on-off with a relay switcher in the model would allow for use of motorised single-channel a&ctuators or even escapements).
Regarding Galloping Ghost, I do not think the PPM frame timing allows for quick enough response to reproduce the GG pulse train; an airborne decoder is required in my view, with a dedicated actuator. I am fortunate enough to have a Controlaire GG actuator and a brand new Ted Strader Go-Ac II, for which I already wrote the code for a decoder.
As said above, it is all great fun and so pleasant to have a reliable single-channel system. 20 years ago, I had made a quite reliable single-channel system on 41 MHz, with FM and a tone filter, to control the Elmic Compact compound escapement in a reduced size deBolt Champion, with the same Baby Bee engine now flying the Halftone.

Keep up the good work.
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Old 07-26-2010, 12:54 PM
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Default RE: 2.4GHz Single-channel

Thanks to Jean-Marie (JMP Blackfoot), I finally got my 2.4 single channel radio built. Not flow yet, perhaps in the next few days. Here is some pics. The push button TX make it much more like the old Single Channel TX from a lot of years ago. The old TX was 27 Mhz Superegen which meant that only one could fly at a time. With the 2.4 of course I can fly with everone else.
Some might say "What is the point?", It is called "Nostalgia"

[youtube][/youtube]
Regards
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