Using Frsky modules in other transmitters (as a 'hack module

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Re: Using Frsky modules in other transmitters (as a 'hack module

Postby rosicrucian » Wed Feb 17, 2010 10:09 pm

received my frsky jr module and 8 channel receiver today,and connected it to my old digifleet transmitter using the 3 pin plug kindly supplied by phil g,thanks again phil. it works fine,just have to work out the best way to attach it to the tranny backplate. glad i opted for the jr one instead of the futaba, dont like the aerial sticking out like that ,seems very vulnerable to me. i can confirm the pinouts are correct,top pin [nearest aerial]is ppm,third pin down is battery positive and fourth pin is battery negative. if the weather's ok i'll try it out in my stryker at the weekend.
mike.
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Re: Using Frsky modules in other transmitters (as a 'hack module

Postby rosicrucian » Sun Feb 28, 2010 7:36 pm

finally got to try out my frsky module and rx in my stryker last weekend, i just servo taped it on my old digifleet tx and fed the 3 wires via a servo plug and socket down the aerial socket. not pretty but it works fine. rock solid control, very impressed and i love the end on pins on the 8 channel rx.
the module runs very cool, thanks to a dc to dc converter. i think frsky is going to prove very hard to beat.
it does have one fault though, it will probably raise the price of secondhand transmitters on ebay!
mike.
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Re: Using Frsky modules in other transmitters (as a 'hack module

Postby Phil_G » Sun Feb 28, 2010 8:47 pm

Excellent, another Frsky convert!
Looks like the JR one does make a neater job than the Futaba, but I'm not over worried about the Futaba one as mines going inside my new tranny once I can get stuck into finishing it!
Phil
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Re: Using Frsky modules in other transmitters (as a 'hack module

Postby rosicrucian » Sun Feb 28, 2010 9:22 pm

phil,
you've got me interested, is this a new tx or one you're building?
mike.
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Re: Using Frsky modules in other transmitters (as a 'hack module

Postby Phil_G » Sun Feb 28, 2010 10:43 pm

Well, its a nostalgia indulgance really.
40 years ago I used to envy the lads who had posh expensive gear with Kraft stick units - so smooth - genuine Kraft sets, Tower Hobbies, the top-of-the-range Skyleader & Staveleys - and I always had a hankering to build a new tranny with Kraft stick units. I've used homebrew sticks and SLMs in past projects but I always thought Krafts were the bees knees, I'm sure Martin (SLM) wont mind me saying that. The ensharker is a 16F690 pic, the rf will be Frsky, and the sticks are.... Kraft! Wahoo! It had a beautiful yellow-on-blue lcd display until yesterday - whilst experimenting with backlight resistors & contrast settings I touched the power on the wrong way and killed it. The pic still works but I'll throw it anyway just to be safe.
Dontcha feel a right numpty when that happens?
Phil
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Re: Using Frsky modules in other transmitters (as a 'hack module

Postby Ashleylad » Mon Mar 01, 2010 10:01 am

Phil, will this work also work on my 10 year old Futaba FF6 computer TX? Can pick up the signals inside and disable the RF stage or use the trainer port as you pointed out in an earlier thread.

cheers

Ash
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Re: Using Frsky modules in other transmitters (as a 'hack module

Postby Phil_G » Mon Mar 01, 2010 12:04 pm

The Frsky module is so tolerant it will work with almost any PPM set. Polarity, level & number of channels is not critical, just 3 wires and go fly! ** EDIT: It has since come to light that the PPM lead needs some protection, a Schottky diode is the preferred method, banded end towards the handset, non-banded end towards the frsky module ***
Removing the crystal & aerial is the easiest way to disable the 35mhz bit.
Cheers
Phil
Last edited by Phil_G on Wed Feb 23, 2011 5:01 pm, edited 1 time in total.
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Re: Using Frsky modules in other transmitters (as a 'hack module

Postby rosicrucian » Mon Mar 01, 2010 10:27 pm

phil,
new tranny sounds great,look forward to hearing more about that. the numpty bit brought back memories. my first rc outfit was a sprengbrook built up from a kit,doug spreng certainly knew his stuff, it worked a treat. i decided to take a look at the waveforms in the transmitter on a heathkit scope i'd just finished building. but i'd left it on charge still plugged into the mains. i must have bridged 2 tracks on the mains side, there was a helluva flash and the tranny would'nt work for some strange reason! it took 2 weeks to get it repaired. i flew it for about ten years without so much as a glitch.
fixed crystal , double tuned front end, and scs desharker, those were the days.
mike.
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Re: Using Frsky modules in other transmitters (as a 'hack module

Postby mikeb » Sat Mar 06, 2010 7:20 pm

As I wanted to experiment with 2.4GHz, I have modified an old Futaba transmitter. I believe it is a Futaba GOLD unit circa 1991. I acquired it from my club when it was pensioned off from training use. The transmitter has an open circuit board, RF module, inside, with 5 pins connecting it to the rest of the transmitter. This is unclipped, and the plastic retainer unscrewed and removed. These match the Frsky module connections (checked with a 'scope), so I made a module mount from polystyrene sheet, and cut a hole in the back cover, as the module was too deep to fit inside. The only problem is the meter on the front of the transmitter goes off the scale when the tranny is switched on. I may investigate further to see if I can fix that, but currently I can revert to the original 35MHz module if required. I test flew an indoor model last Tuesday, before I had cut the hole in the case so flew with the back not fitted. I used a 4 channel rx in the model, and had no problems. I have yet to carry out any full range checks.

Front.jpg
This is the transmitter.

OldModule.jpg
The old module with plastic retainer.
OldModule.jpg (8.85 KiB) Viewed 2021 times

Case.jpg
The new module housing fitted.

MountedRear.jpg
The Frsky module fitted.

MountedSide.jpg
Side View.

MountedFront.jpg
Front view.


Mike.
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Re: Using Frsky modules in other transmitters (as a 'hack module

Postby Andy2No » Fri Mar 12, 2010 11:06 am

Phil_G wrote:You will need three connections to your transmitter, conveniently made with 3-way servo wire. Ground is easy. The ground plane of the transmitter PCB is usually obvious - if not, find the black wire from the battery.
Next you need a switched positive battery supply. This can be taken from the switch or from the board, whichever is most convenient. Finally you need the PPM signal. The easiest place to find this is on the back of the trainer/sim port. Here is an excellent source of buddybox connections.
Whilst you're inside the transmitter, you need to stop the it emitting any 35mhz signals, so remove the crystal, and also remove the 35mhz aerial.
Thanks, Phil.

Which end of the Futaba buddy lead diagram should I be looking at? Is the transmitter a master or a slave? I've never owned a buddy lead.
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