Switching between modules

[aesmith]

Hi,

I have a 9x with internal Frsky module. I'm starting to feel the need to support other modules, to use the set with RTF or similar models. For example I have an indoor helicopter that can be used with the Flysky 2.4 system, some of the others need DSM2 or DSMX.

Would it be practical to install a plug-in module while leaving the Frsky in place, with a changeover switch so that only one of the two is powered up? Any links to articles where anyone's done something similar would be appreciated.

thanks,

Tony S

[ShowMaster]

I believe a search will find info on members that have done that.
If you convert back to using modules you can just change a module to the protocol your want to fly as another option.
Frsky, Turnigy/FlySky, Spektrum rf deck in a module, or the new HK DSM orange module once the updated version goes back on sale.
To use the internal Frsky and other plugin modules my thinking is to only use one at a time. There is some interaction from having 2 antennas close coupled powered or not. Keeping 1 horizontal and one vertical can give you as much as 20dbm isolation as a precaution if both systems are in use or not.
The only other issue is if the 9x ppm signal can drive 2 modules. There are workarounds if that is an issue from installing a resistor in the ppm line to adding a switch. Others I'm sure sill comment on what works for them after reading this.
It's all doable so just post what rf decks you plan to use.
Personally I went the all module route to save the internal case room for the audio board or other hardware additions.
To use 16 ch however both the internal DHT and DJT module will be required. Pretty much the same setup you'll use for adding DSM.



ShowMaster
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[aesmith]

Thanks. The configuration I'm considering at the moment is to have a Turnigy/Flysky v2 module in the back, while keeping the Frsky that's already mounted internally. So my question really boils down to can I do this if I (1) switch off the power to the internal module and (2) remove the Frsky antenna? Or do I need to switch off the ppm feed to the Frsky as well?

[Kilrah]

You'll need a 2-pole switch that switches both power and PPM between the internal and external modules.
Some modules like the Flysky one pull the PPM signal down when they're not powered, so it's best isolated.

[ShowMaster]

Like this

Never power a tx module with the antenna removed. Best is to keep the at 90 Deg from each other and don't remove them.

Note,
The Frsky modules and DHT don't load down the PPM 9x circuit like the FlySky/Turnigy modules do, so you may not need to switch the PPM inputs. You will however, if you're going to mix and match other brands and types of modules, so switching the PPM line is the best option for everything used.

Drawn in my iPod touch so feel free everyone to redraw.
SM


ShowMaster
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[aesmith]

Thanks everyone, I think I'll play safe with a DP switch. I'd like to see if I can mount it somewhere where I won't hit it by mistake, and was toying with the idea of a push-to-break switch that's activated when a module is installed. Advantage is that it's idiot proof, disadvantage is that I need to remove the module more often.

[kaos]

Thanks everyone, I think I'll play safe with a DP switch. I'd like to see if I can mount it somewhere where I won't hit it by mistake, and was toying with the idea of a push-to-break switch that's activated when a module is installed. Advantage is that it's idiot proof, disadvantage is that I need to remove the module more often.

Use a slider DP switch, I found they usually come with a long slide knob/stick, longer than the Tx box thickness. grind down the slider protruding out of the Tx box, it will be flush with the tx box. You won't hit the switch by accident. you may have to use a pen, or press hard, to switch back and forth.
I think the 'idiot' proof approach may be not needed. if you choose the wrong module, the rx won't even bind. Kilrah and SM may be able to elaborate more on how the trainer function is going to be affect, or any at all, when switching modules. ??

[ShowMaster]

Just thinking through.
I don't think you want to remove the module many times. You don't want to wear out the fm connector pins.
The DPDT slide SW idea is a better choice. There are small footprint ones. To avoid taking a lot off the switch slide you could recess it with washers into the case a little making it flush. A V cut into it would allow the slot to be small and still be able to switch it.
Another idea is there are small slotted rotary switches that mount with a small nut. They may be hard to find.
Dip switches are also small. I've used them on my ham radio walkie talkies to switch tone functions. Just CA them into a cut rectangle hole. Miniature toggle switches maybe in the battery compartment?
As for the trainer function
The ppm signal. Usually the issue is that non Frsky modules loads down the ppm out on the trainer 9x. If you leave it in the Frsky mode it shouldn't.
This may need more brainstorming but I think I'm correct. The master 9X shouldn't care what module is being used as long as the input ppm is 5v ptp direct or converted and the 9x trainer mode is on and channel mapped to match.
This last part is something the needs to be verified.
SM



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[manu]

Just thinking loud:
Isn't it. possible put in a relais controlled by the current of plugged in RF Module. When there is current the Relais should interrupt the connection of the built in Module?

[Kilrah]

Hmm, one of the goals was to be able to leave the module in place...

[pmullen503]

Thanks everyone, I think I'll play safe with a DP switch. I'd like to see if I can mount it somewhere where I won't hit it by mistake, and was toying with the idea of a push-to-break switch that's activated when a module is installed. Advantage is that it's idiot proof, disadvantage is that I need to remove the module more often.

Here's where I put mine, where the Turnigy badge was. LED indicates internal module is powered. It's out of the way yet still convenient.

[ShowMaster]

Thanks everyone, I think I'll play safe with a DP switch. I'd like to see if I can mount it somewhere where I won't hit it by mistake, and was toying with the idea of a push-to-break switch that's activated when a module is installed. Advantage is that it's idiot proof, disadvantage is that I need to remove the module more often.

Here's where I put mine, where the Turnigy badge was. LED indicates internal module is powered. It's out of the way yet still convenient.

Good enough, does the job.
SM


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[kaos]

pmullen503: where do you put the DHT switch (for flashing, etc...) on the Tx? or you leave it inside the Tx?

[pmullen503]

I have a Spektrum module inside, so no need to access it. That's one of the reasons I went with a Frsky plug in module and internal Spektrum and not vice versa.

[ShowMaster]

When I used a DHT some time ago I mounted it on back

ShowMaster
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[Kilrah]

pmullen503: where do you put the DHT switch (for flashing, etc...) on the Tx? or you leave it inside the Tx?

On the radio on which I installed an internal module, I simply didn't mount the switch (it had a plug that got into a socket on the LED/pushbutton board).

I only have telemetry receivers (no need to change the mode), and I just figured if I needed to flash I'd open the radio and plug the switch temporarily jsut for that. That was a year ago, and there hasn't been an update since then. Of course it's well thought out, and no switch = telemetry mode.

[kaos]

Is there any effect on the trainer function when switching between modules?

[kaos]

any of you set these 2 modules up and run both module at the same time (PPM16)?

[aesmith]

Here's where I put mine, where the Turnigy badge was. LED indicates internal module is powered. It's out of the way yet still convenient.

That's neat, but unfortunately that's where I put the Frsky switch/LED panel on mine ...



I think first thing I need to do is look though my bits and bobs and see what sort of DPDT switch I can lay my hands on. Then work out where to fit it. Slide switch sounds the best bet if I can find one to suit.

Tony S

[ShowMaster]

any of you set these 2 modules up and run both module at the same time (PPM16)?

I never tried? Now that you mention it I guess I just have to plug in a DJT module and give it a try. I did the DHT mod right at the start after blowing up my DJT module because I missed the ground on the 9x module pins back plane. All I had was a spare DHT.

I'll give 16 ch a try after I read up on how to set it all up.
So how do I get 8 ch of ppm to each Frsky module from 1 ppm line ?
Ok, off to wiki to find out?


ShowMaster
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[Kilrah]

I have, DJT in the back and DHT-U connected to trainer port. Easy, works fine. Only used on the bench though, never in real life as I've never had the need (or didn't want to bother with the installation and losing my trainer port for just the one extra channel I was missing).

[MikeB]

Select PPM16, then 8 channels are 'normal' and the second 8 are on the trainer jack.

Mike.

[ShowMaster]

On the trainer port! Now I remember reading that some time ago.
I also remember why I didn't try it.
I wanted the buddy box for non 9x tx option so I installed Gruvins mod on my 4066 circuit. If I remember that won't allow this option to work
I now also understand the recent posts on the external 1 transistor level converter for the trainer cord does work.
If all this is true ill remove the Gruvin mod from the 4066 circuit and go external with the newer posted one and I'm good to use the trainer port again.
SM


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[aesmith]

Select PPM16, then 8 channels are 'normal' and the second 8 are on the trainer jack.

Mike.

Changing the subject a little, if you had one RF module installed as normal, and one via the trainer port (a'la Anylink), then could you switch between them by selecting "ppp-sim" for the trainer connected module?

[Kilrah]

This would indeed cut signal to the main module, but it would still receive power. Some modules still transmit even if they don't receive a signal, so it might not be what you want.

[pmullen503]

While we are on the topic of the trainer port, is there a photo or schematic showing where to pick up the trainer PPM signal? I don't use the trainer port for sim or buddy box and was thinking of removing it and installing a port or connector dedicated for PPM16 work.

[khairuv]

I have, DJT in the back and DHT-U connected to trainer port. Easy, works fine. Only used on the bench though, never in real life as I've never had the need (or didn't want to bother with the installation and losing my trainer port for just the one extra channel I was missing).

Kilrah,

Are those DHT-U (trainer ppm) and DJT (ppm) work together okay for 16 channels? Another question is how to assign the 8 upper channels (9-16). Is it like assigning normal channel? And how about the binding procedure? It is one at a time or two modules must be on and bind one by one or simultaneously?

[kaos]

Ok, back home now. Just noticed my DHT has different 'panel' than SM and aesmith. Yours are much better than mine.

yours with dip switch is much better. Are there different version of DHT? I wonder if I can attach a dip switch on the little board to change from 1 way, 2 way or FW flash?

[ShowMaster]

Mine is the order version,maybe a year ago now. I think many complained about the dip switches so Frsky made the newer toggle version?
I have both from past purchases.
If you unplug the toggle switch on yours it defaults to the 2 way mode.
I only fly 2way so not a big deal either way. A miniature toggle maybe could be used. Adding dip switches on another board and mounted to the case is one idea.
Depending on what you put in the battery compartment the toggle switch may fit there.
When I needed to mount a dip switch in my ham walkie talkie I just cut a matching hole in the case and CA glued it in flush.
A micro size dip switch should mount the same way as well.
Just some switch and mounting ideas.
SM


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[kaos]

Thx, SM. I don't know why people complain about dip switches. they are a lot neater to mount and won't be tripped by accident.
also good to know it is 2way when the toggle is not mounted.