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Fitting an FRSky hack module to a 35MHz Cockpit SX

Started by Yoyo, March 29, 2011, 18:49:38 pm

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Yoyo

For a while now, I've been using an FRSky Futaba module (DFT) with my 35MHz cockpit SX. I used a cable from the trainer port to supply power and PPM to the module. It worked brilliantly, but it was pig ugly....

[smg id=26406]

So once the new two-way hack module (DHT) came out and I had the kit to upgrade my existing receivers to V2, I decided to fit one inside the tranny.

Slightly prettier on the outside:

[smg id=26403]

But where is the range check button and the LEDs, you ask? Look through the antenna storage hole...

[smg id=26405]

I did have to experiment quite a bit to fit it inside the very slim case:

[smg id=26407]

And for reference, here are the connections to make on the back of the trainer port:

[smg id=26404]

Everything is hot-glued into place (and for strain relief) so can be removed again if needed. I'd probably put a connector in between the module and the trainer port next time, so you can take the case completely apart.

I hope that helps anybody else planning this mod. It works fine, and still charges normally through the trainer port.

Next on the list is a LiPo, although really the NiMh pack fittted now seems to go on forever. The space would be nice though, it's a bit tight between the battery and the LED board.
Doing what you like is Freedom
Liking what you do is Happiness

Thoughtful_Flyer

Well, I think it looks excellent and is far better than an external module relying on a plug and socket.

Sadly some people will say you have committed a hanging offence and will certainly be banned from some show flight lines !

One design weakness is the lack of warning when in range check mode. On Spektrum you have to hold a button down for the whole range check. Futaba (on the complete transmitters at least) bleeps every few seconds. However all you have is a light which turns green when the power is reduced AND the low power locks on until you press the button again or turn the transmitter off. This is a stupid piece of design in my view - you may wonder how I know that..........................

Yoyo

Quote from: Thoughtful_Flyer on March 29, 2011, 19:16:59 pm
Well, I think it looks excellent and is far better than an external module relying on a plug and socket.

Sadly some people will say you have committed a hanging offence and will certainly be banned from some show flight lines !

One design weakness is the lack of warning when in range check mode. On Spektrum you have to hold a button down for the whole range check. Futaba (on the complete transmitters at least) bleeps every few seconds. However all you have is a light which turns green when the power is reduced AND the low power locks on until you press the button again or turn the transmitter off. This is a stupid piece of design in my view - you may wonder how I know that..........................


You know that because you have a one way module - the two way has always beeped continuously in range check mode. It also never had the GUID problem (however small that problem actually is in actuality).

With those and also having a live signal strength and battery low indicator built in, I can't see why anybody wouldn't go for the two way module, especially now. If only they would sort it so that the two way module could bind directly to the one way receivers instead of needing a switch to be thrown, it would be a very easy upgrade for those early adopters with lots of one way kit as well.

As for going to shows, the last one I went to had the commentator continuously complaining about *everything* that wasn't exhibiting 'proper scale behaviour' - including some excellent 3-D flying and other great show-off pieces. I can do without that...

Doing what you like is Freedom
Liking what you do is Happiness

Kozmyk

Some of those RC Airshow commentators really should have a Waffle Filter on their mic channel.
Nerdy drivel of the worst kind.
Do they go to the Arthur Pewty School of Inane Droning to learn this ability?
I'd post YouTube links if it weren't for fear of upsetting the "wrong" people. ;)
Some Helis ... Some planks ... Phoenix/SimStick

bennyh

Thanks so much for posting this YoYo as I was planning on doing the same as you.
Was considering the one-way kit, but sounds like 2 way is better option overall.
You mention live signal strength and battery low indicator (of the FrSky)...how do you access these functions from the SX exactly? Is it possible to get a receiver voltage display on the hacked SX?
Cheers
Ben

Yoyo

Quote from: bennyh on April 08, 2011, 12:55:15 pm
Thanks so much for posting this YoYo as I was planning on doing the same as you.
Was considering the one-way kit, but sounds like 2 way is better option overall.
You mention live signal strength and battery low indicator (of the FrSky)...how do you access these functions from the SX exactly? Is it possible to get a receiver voltage display on the hacked SX?
Cheers
Ben


2 way is way better, I wouldn't be without it, same as 2.4 instead of 35MHz.

The signal strength and battery are done by sound - it's plenty loud enough to hear from inside the case, even out on the slope.

I have heard of a couple of ongoing projects to display the voltages and RSSI (signal strength) on an LCD, but frankly I wouldn't bother. I'm always too busy to look anyway, aren't you?

One feature of the two way system that doesn't get mentioned much is that as well as the 'spare' A-D input, it also has a telemetry channel for user data - again, there are a couple of projects to have a sensor hub in the plane and send altitude, speed, G, engine temps, RPM etc. etc. back to a display on the tx.

None of these extra projects is mature yet though, and like I said battery and RSSI are the most useful and come as standard.

I've been out flying with my hacked SX half a dozen times now, it's worked perfectly and having it internally just feels way better than having a box stuck on the back.

If you do it my way, do watch out for the battery pack and LED board clashing - I had to cut a small amount of the plastic away to get clearance and to get a flat surface to stick it to. Maybe I should have done a LiPo/A123 conversion at the same time...

Doing what you like is Freedom
Liking what you do is Happiness

bennyh

Magic Yoyo. Just what I needed, will do this soon.
I wonder if the beeping would get irritating after a while though. Perhaps a headphone socket would be good.

Yoyo

Quote from: bennyh on April 09, 2011, 07:27:25 am
Magic Yoyo. Just what I needed, will do this soon.
I wonder if the beeping would get irritating after a while though. Perhaps a headphone socket would be good.


It only beeps when something's up. Quiet is good!
Doing what you like is Freedom
Liking what you do is Happiness

ddark

I have fitted FrSky (no telemetry) module in my Cockpit SX, you can some photos here (it's Croatian language but pictures tell everything):
http://www.flyfreak.net/elektronika-i-baterije/cockpit-sx-hakiran-sa-frsky-2-4-ghz/

Yoyo

Quote from: ddark on May 07, 2011, 08:03:03 am
I have fitted FrSky (no telemetry) module in my Cockpit SX, you can some photos here (it's Croatian language but pictures tell everything):


You did a neat job with the antenna. I was tempted to do that but I wanted to keep the option of using it for 35MHz. Probably won't ever use it on 35MHz though...

I think with the range check issue I'd have tried to put the LED on the front, but the button is well enough protected there anyway so it should be fine.

Thanks for sharing.
Doing what you like is Freedom
Liking what you do is Happiness

bennyh

Hi Yoyo,
I've now done a copycat install. All seems to work well. One slight concern is that the bind button PCB seems to be getting crushed by the battery. Did you remove any of the case material?
All in "multiplex 2.4" for £80. Bargain. :)

Yoyo

Quote from: bennyh on May 21, 2011, 13:49:52 pm
Hi Yoyo,
I've now done a copycat install. All seems to work well. One slight concern is that the bind button PCB seems to be getting crushed by the battery. Did you remove any of the case material?
All in "multiplex 2.4" for £80. Bargain. :)


I did - I removed some of the angled supports round the hole to give the button/led PCB a flat surface to glue onto.

I'm also thinking of fitting a Lipo instead which will make loads of room - just bring the balance lead out  so you can charge through it pretty safely while it's still in the tx.

Not sure yet whether it will work with a 2S but a 3S is too much.

Doing what you like is Freedom
Liking what you do is Happiness

bennyh

bu66er it, I've knocked off the bind microswitch when I tightened up the case! Unlike Yoyo I'd not removed any plastic from around the little hole.

To make things worse I heated the switch up with a haridryer to remove the hot glue, and it blew away into nowhere. Luckily I already bound my Rx, and all works fine, but this will need sorting out sooner or later. I guess I can get any push-to-make microswitch and solder it onto the board, but it would be nice to find the correct component to replace it. Any ideas how to go about finding this bit?

THe other thing is that my 8Ch receiver is too big for my glider unless I remove the case. Is this acceptable if I cover it in electrical tape and take precautions to avoid the bind switch being activated mid flight?

bugsb

Quote from: Yoyo on May 21, 2011, 14:03:56 pm
I did - I removed some of the angled supports round the hole to give the button/led PCB a flat surface to glue onto.

I'm also thinking of fitting a Lipo instead which will make loads of room - just bring the balance lead out  so you can charge through it pretty safely while it's still in the tx.

Not sure yet whether it will work with a 2S but a 3S is too much.

my sx has been running on a 2 cell 2100 since new (2 years) a 3 cell is way to much
Ron
Any spellng mistak is don with full intend to amuse the reder, so if you find one you can have it fo

Yoyo

Quote from: bennyh on May 21, 2011, 18:32:05 pm
bu66er it, I've knocked off the bind microswitch when I tightened up the case! Unlike Yoyo I'd not removed any plastic from around the little hole.

To make things worse I heated the switch up with a haridryer to remove the hot glue, and it blew away into nowhere. Luckily I already bound my Rx, and all works fine, but this will need sorting out sooner or later. I guess I can get any push-to-make microswitch and solder it onto the board, but it would be nice to find the correct component to replace it. Any ideas how to go about finding this bit?


Whoops.

You could maybe take the opportunity to wire in a small switch that you can mount on the case somewhere more useful? Not somewhere you'd press by accident though, as it does both bind and range test.

I'd do that as it gives a stronger connection than the surface mount which, as you've found, isn't too robust.

If you want the original style, it could be this one?

Quote from: bennyh on May 21, 2011, 18:32:05 pm
THe other thing is that my 8Ch receiver is too big for my glider unless I remove the case. Is this acceptable if I cover it in electrical tape and take precautions to avoid the bind switch being activated mid flight?


They are chunky, aren't they. I can't see a problem with doing that, as long as the aerials still stick out. Apparently some types of black electrical tape block radio signals (Carbon in the dye?) and some heatshrinks are too thick and can cause overheating problems, but a bit of insulating tape should be fine.


Doing what you like is Freedom
Liking what you do is Happiness

Yoyo

Quote from: bugsb on May 21, 2011, 18:39:37 pm
my sx has been running on a 2 cell 2100 since new (2 years) a 3 cell is way to much
Ron


Is that the M-Link or the 35MHz? I've seen reference to the M-Link being fine with LiPo's, can't find any confirmation about the 35MHz version though. I suspect they are quite different inside.

Doing what you like is Freedom
Liking what you do is Happiness

bennyh

You are a gentleman and a scholar Yoyo!
I can't see any big advantage in running a Lipo over the existing NiMH. You may worry about fires etc too.
Cheers
Ben

Yoyo

Quote from: bennyh on May 21, 2011, 19:04:02 pm
You are a gentleman and a scholar Yoyo!
I can't see any big advantage in running a Lipo over the existing NiMH. You may worry about fires etc too.


Apart from cramming everything into the case?  $%&

I guess with Instants in the Tx then there isn't much difference between LiPo and NiMH for it.

I have a pile of good 2000mAh LiPo cells stripped from a few laptop battery packs though, looking for a new use ;)

I'll use 2 for my new toy th-9x transmitter, so I can have a play with programming that next.

Can't seem to find time just now though. Moving house on Friday.
Doing what you like is Freedom
Liking what you do is Happiness

BrianB

May 22, 2011, 15:40:28 pm #18 Last Edit: May 22, 2011, 15:45:36 pm by BrianB
I don't honestly feel fitting a LiPo in an M-Link Tx would offer any tangible advantage, as the M-Link Sx Tx will run for 15 hours or so on it's standard 6 cell pack. The M-Link Evo will do 25+ hours, but that has a slightly larger capacity pack (2100mah as against the Sx's 1800mah).

A LiPo pack would of course need to be removed for safe charging, whereas a Nimh pack does not. I've no idea if the battery management software of some Mpx transmitters will handle LiPos.
Westmorland Model Flyers (Scratch built models preferred, but artf's if you really must)
Windermere Model Waterplane Flyers

marcellus

May 22, 2011, 15:49:16 pm #19 Last Edit: May 22, 2011, 15:52:42 pm by marcellus
NiMh give plenty of capacity these days.

The big downside of Lipo for me is leaving the Tx on overnight by mistake. One very dead pack.

It doesn't do NiMh any good but it doesn't seem to kill them in one shot.

I remove my Tx pack for charging in any case.

Yoyo

Quote from: marcellus on May 22, 2011, 15:49:16 pm
NiMh give plenty of capacity these days.

The big downside of Lipo for me is leaving the Tx on overnight by mistake. One very dead pack.

It doesn't do NiMh any good but it doesn't seem to kill them in one shot.

I remove my Tx pack for charging in any case.


Removing for charging is a pain with the Cockpit SX as it doesn't have a battery cover, you have to take the back off and the screws are only into plastic so they wear out quickly.

I'd feel safe enough balance charging it as the currents and potential overheat are minimal compared to full on charge. It takes longer, but that shouldn't be an issue for a tx.

Like I said, an Instant-T NiMH is better for this job anyway, except that it's bigger.
Doing what you like is Freedom
Liking what you do is Happiness

Kozmyk

May 23, 2011, 03:50:28 am #21 Last Edit: May 23, 2011, 03:56:41 am by Kozmyk
Quote from: bennyh on May 21, 2011, 18:32:05 pmTHe other thing is that my 8Ch receiver is too big for my glider unless I remove the case. Is this acceptable if I cover it in electrical tape and take precautions to avoid the bind switch being activated mid flight?

If you can live with 6 channels then the D6FR Rx is much smaller and still has telemetry.

For Tx packs I'm moving over to LiFePo. They happily charge at 1C so no overnight wait if you forgot to check last night. ;)
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idproduct=14076
So far two for my Turnigy 9X project Tx's, my DX7 NiMh is still going strong but there's always the chance I'll forget to check it. :)
They DO need removing though, only for the connections; they don't get hot when charging.
Some Helis ... Some planks ... Phoenix/SimStick

Yoyo

Quote from: Kozmyk on May 23, 2011, 03:50:28 am
If you can live with 6 channels then the D6FR Rx is much smaller and still has telemetry.

For Tx packs I'm moving over to LiFePo. They happily charge at 1C so no overnight wait if you forgot to check last night. ;)


You cant use the D6FR with a cockpit SX if you have flaps though - it won't let you reassign ch4 from throttle to a flap channel, only to a few other things.

So you always need a 7ch rx for a six servo glider. A great pity.

Lifepo look good, but as others have said NiMH works just as well for this use too, and if you can get a pack made in the right shape then the capacity matches Lifepo  too.
Doing what you like is Freedom
Liking what you do is Happiness

Kozmyk

Quote from: Yoyo on May 23, 2011, 07:33:50 am
You cant use the D6FR with a cockpit SX if you have flaps though - it won't let you reassign ch4 from throttle to a flap channel, only to a few other things.

So you always need a 7ch rx for a six servo glider. A great pity.

So near yet so far eh? Frustrating.

Quote from: Yoyo on May 23, 2011, 07:33:50 am
Lifepo look good, but as others have said NiMH works just as well for this use too, and if you can get a pack made in the right shape then the capacity matches Lifepo  too.

Yeah. I'm not going to change out the DX7 pack just to be in fashion. ;)
Faster charging IS a plus feature but not enough to waste a perfectly good NiMh pack.

With the 9Xs the choice was new pack or an ill fitting AA battery holder.
At least, they were ill fitting with rechargeable AAs in.
Could hardly get the battery cover on the Tx with AAs.
Some Helis ... Some planks ... Phoenix/SimStick

bugsb

May 24, 2011, 19:48:01 pm #24 Last Edit: May 24, 2011, 19:49:26 pm by bugsb
Quote from: Yoyo on May 21, 2011, 18:47:32 pm
Is that the M-Link or the 35MHz? I've seen reference to the M-Link being fine with LiPo's, can't find any confirmation about the 35MHz version though. I suspect they are quite different inside.

its the 35mhz which leaves alot more room for the 2.4g mod i want to add a sw to mine so i can use it as 35mhz and 2.4g
Ron
Any spellng mistak is don with full intend to amuse the reder, so if you find one you can have it fo

Yoyo

Quote from: bugsb on May 24, 2011, 19:48:01 pm
its the 35mhz which leaves alot more room for the 2.4g mod i want to add a sw to mine so i can use it as 35mhz and 2.4g
Ron


Excellent thanks, I'll keep it in mind when I need to replace the NiMHs.

I've never been on 35 at all so mine is all 2.4 and always will be.

As far as flaps with a 6ch rx are concerned, I was thinking... (no, really)

Other than mixed flap/aileron, for everything else both flaps do the same thing. So if I just give that up (the ailerons are big enough anyway) and use a Y-lead to do both flaps from the one working flap channel, I can still do crow, camber and reflex with a 6ch rx. I might try that in my Acacia when I find it again...
Doing what you like is Freedom
Liking what you do is Happiness

bennyh

May 25, 2011, 07:02:02 am #26 Last Edit: May 25, 2011, 07:21:55 am by bennyh
Re my broken off binding microswitch mentioned earlier:
I contacted FrSky and they offered a free replacement remote PCB if I paid postage from the factory. Great. Only problem is postage was quoted at 24usd for a <5g item! I bought the entire hack module for 23usd at hobby king. They said sorry it was like this, and communications were very impressive anyway.

I've bought the smallest microswitch in Maplins and I'm soldering it to the board later.

Reading the manual, it looks like signal strength is automatically sent to the transmitter, but receiver battery voltage requires a voltage sensor to be plugged into the A port on the side of the Rx. I assume you then need some sort of screen read-out at the Tx end then?

I had range problems with a fake Spektrum rx in my plank so I'm going to put Frsky in this too, once the 4 channel D-series receivers come out. Hopefully they will be cheap as chips.
Looking forward to a double maiden of Frsky module and Ocelot next week sometime....

Patmac

Quote from: Yoyo on May 24, 2011, 21:23:28 pm

Other than mixed flap/aileron, for everything else both flaps do the same thing. So if I just give that up (the ailerons are big enough anyway) and use a Y-lead to do both flaps from the one working flap channel, I can still do crow, camber and reflex with a 6ch rx. I might try that in my Acacia when I find it again...


If you use a Y lead for flaps they will work in opposition like ailerons unless the servos are mounted asymmetrically.
AFAIK the electronic Y lead only works in "Easy" mode & with ch 7 but something should be possible with a free mixer.
Pax vobiscum

Yoyo

Quote from: Patmac on May 25, 2011, 23:07:17 pm
If you use a Y lead for flaps they will work in opposition like ailerons unless the servos are mounted asymmetrically.
AFAIK the electronic Y lead only works in "Easy" mode & with ch 7 but something should be possible with a free mixer.


I'll have to experiment when I can find my planes again. I bought a house today(completed) and we're all packed up to move...
Doing what you like is Freedom
Liking what you do is Happiness

tomkfly

May 26, 2011, 08:11:43 am #29 Last Edit: May 26, 2011, 08:12:46 am by tomkfly
Quote from: bennyh on May 25, 2011, 07:02:02 am


Reading the manual, it looks like signal strength is automatically sent to the transmitter, but receiver battery voltage requires a voltage sensor to be plugged into the A port on the side of the Rx. I assume you then need some sort of screen read-out at the Tx end then?



I believe the Rx battery voltage is standard and the voltage sensor is to measure additional batteries, such as the power pack in an electric or ignition in a petrol.

  Tom
When you change the way you look at things, the things you look at often change.        www.deesidemac.co.uk
Gravity, thou art a heartless bitch

Yoyo

Quote from: tomkfly on May 26, 2011, 08:11:43 am
I believe the Rx battery voltage is standard and the voltage sensor is to measure additional batteries, such as the power pack in an electric or ignition in a petrol.

  Tom


The original D8R had two A/D inputs and needed a voltage divider thing to plug in the side, the V2 D8R has one of the A/D inputs internally connected so it always measures the rx voltage.

You can still use the other input to measure external battery voltages if you want.
Doing what you like is Freedom
Liking what you do is Happiness

Grasshopper

Yoyo and others -

with an SX you can use a 6 channel receiver on a 4 servo wing glider. Re-assign channel 4 to be SP->S4 and with a bit of fiddling it works OK. The servo zero setting does nothing. Use the travel + and - to set the 'off' point and the full travel point. I have done this on a Luna and it - well just works! :)

Peter

bennyh

I found another good place for the bind switch/LED break out board:
Unscrew the plastic part that acts as a retainer for the 35Mhz aerial and it leaves behind a nice little window in the back of the case.
Does anyone else find it very easy to round the heads of those torx screws? Well this gives you two spare screws as a bonus!
Seriously considering sourcing some screws that have a hex or pozidrive head instead.....