Reverse Current Protection Mod for 9xtreme

[bob195558]

Thanks Klaus, I see it now.
For me when trying to use straps around the neck and when bending over to make final adjustments to the model,
the RC radio would swing around causing damage and/or potential damage and is a real danger.
Everyone in our RC group does Not use the straps around the neck, but sets the RC radio on the ground
so to have two hands and full attention when making any adjustment to there models before flight.

Bob B.

[s_mack]

Are you kidding me?

► Show Spoiler

(those 2 "skies" are a slim line foldable tx-tray)

WP_20151106_19_35_34_Pro (Klein).jpg

Klaus

I wasn't joking, no lol. From the photo I thought the two u-channel rails would insert into something or bolt on to something. I get it now.

[KAL]

I used this method more than 40 years ago when I started my RC career when the
thumb method was not en vogue at all and so I do now for a few years since I restartet after 30 years ...

No final adjustments when the TX is hanging from my neck!
If there is the need to I do take the time to remove the TX!
Hustle and bustle is no good ...

Nevertheless I appreciate the existance of a sticky throttle kill especially with electric engines

Klaus

[LTMNO]

In absence of a helper for taking a picture ...

WP_20151106_21_06_49_Pro (Mittel).jpg

Just curious.. what is hooked up to the second antenna?

Did you work something out for Diversity?

Thanks.

[LTMNO]

P.S. my Reverse Mod worked fine...

Thanks for posting...

[ckleanth]

Gents, can someone explain why someone would do this modification? is it just to prevent damage from accidentally plugging the battery the other way round?

[MikeB]

Exactly!
The 9Xtreme was supposed to have this feature, but we got it (slightly) wrong!

Mike.

[ckleanth]

Exactly!
The 9Xtreme was supposed to have this feature, but we got it (slightly) wrong!

Mike.

cheers mike

[KAL]

... Just curious.. what is hooked up to the second antenna? ...

One antenna for DHT and the
other for a spektrum hack module.

Klaus

[LTMNO]

... Just curious.. what is hooked up to the second antenna? ...

One antenna for DHT and the
other for a spektrum hack module.

Klaus

Very cool.... thanks.

[jhsa]

This Diode will do the trick, correct?
MBRA340T3G , SMD Schottky Diode , 40V/3A

Thanks

João

[MikeB]

Looks quite suitable.

Mike.

[jhsa]

As some of you might already know I have been working on a little project that is supposed to make my radios a bit safer.
Recently I had a little problem with my 9XR-PRO power switch. As you know the 9x/9XR-PRO power switch switches 2 independent circuits. One is the power to the mainboard, and the other is the power to the RF module, as well as a detection circuit that will let the processor know if the power switch is ON or OFF.
So on my radio one side of the switch was/is switching ON and OFF before the other. That means the radio thinks it is OFF while it is still ON. That is not good. Then it hit me that a bad connection on the power switch while flying a model would be a disaster as once the CPU thinking it is time to sleep, it doesn't recover even if the switch connects again. Mike, kinda fixed that on the pro firmware, but I think the others still don't have it? The pro seems to be working better even if sometimes I still see "Shutting Down" when I turn the radio ON. But is doesn't hang anymore.
So, after all that, I have been working on some circuit that keeps the radio ON even if the power switch fails completely. At the same time I am also trying to improve the reverse polarity protection.
I have something already working for the 9x radio with stock board.
I also have something working for the skyboard and Ar9x boards. Actually I etched a new power switch board and installed it on my 9x with skyboard, and it is working.
But I have a question or two about the 9xtreme board.
Does the 9xtreme have some reverse polarity protection at all?? I know we have to ( or should) solder a diode to the switch board. But apart from that, is there any other protection circuitry on the board? A diode, a mosfet?

Also, I see that most (if not all the boards) use a schottky diode as reverse polarity protection. I remember suggesting this a few years ago, even before the sky board, and I have been told at the time that it wasn't a good idea because the voltage reading would not be accurate. Now all boards use it. So we could have probably avoided many of us destroying their 9x radios

Is there a good reason for using a diode instead of a mosfet as reverse polarity protection, apart from the price of course?
A mosfet offers practically no voltage drop when it is conducting, if it is completely turned ON. So, the voltage reading would be more accurate. Talking to some people, I have learnt that many prefer the mosfet approach, hence my question.

Thank you for your answers

João ( the person that is an absolute ignorant in electronics according to at least one person ).

[MikeB]

The 9Xtreme does have a MOSFET to provide reverse battery protection, but the power switch bypasses it, hence the suggestion of adding a schottky diode on the switch board. I'm fairly certain the mosfet(s) shorts out the diode when the soft power switch turns on, so no actual voltage drop.

Mike.

[bob195558]

Hi,
Here is a video which João made titled Safe Power Switch 1: (https://www.youtube.com/watch?v=VACPx3wq66s).

Bob B.

[jhsa]

The 9Xtreme does have a MOSFET to provide reverse battery protection, but the power switch bypasses it, hence the suggestion of adding a schottky diode on the switch board. I'm fairly certain the mosfet(s) shorts out the diode when the soft power switch turns on, so no actual voltage drop.

Mike.

So, huummm, then maybe.... I'm just guessing.. Please have a look at the pictures.. Sorry about the questions, but I don't want to damage my board. Therefore I'm asking before I mess up

Based on what you said above, is this close to the 9XT power circuit? If so, that means the protection MOSFET is doing nothing there. It only protects the board when the power switch is OFF and powered by the trainer circuit, right?

Then, is this the way it should have been done so the board is completely protected without the diode?
i can see a problem with the charging circuit though.. but I think that could be solved.
On my little project that wouldn't be a problem because I switch the Charge negative instead

Thanks for your advice

João

[Crusader]

Hello Gents,
I am just starting to mod out my FS-TH9X Radio, 9xtreme board in and working great (love this board..)
it appears a lot of you are doing this...

----------------------------------------------
I have unsoldered/removed three components:
Regulator, Transistor, Buzzer and also I removed the old Antenna Contact Bracket.
----------------------------------------------

as in Bob's post and other cut the PCB completely, Can I please confirm before I do my reverse polarity diode fix
that removing these 4 items from the board does not reduce the functionality of the radio?
especially removing the bracket..

I know a stupid question, I just really want to make sure, from the people that know.

Regards,
Neil

[jhsa]

You don't need the regulator on the switch board. also don't need the transistor and buzzer., You can also remove the metal thingy that connects both halves of the radio.. ;(

None is needed..

João

[Crusader]

You don't need the regulator on the switch board. also don't need the transistor and buzzer., You can also remove the metal thingy that connects both halves of the radio.. ;(

None is needed..

João

Thanks for the confirmation.

Neil

[jhsa]

Just being nosy here.. I understand why you would remove the bracket, but why removing the regulator, transistor and buzzer? I know they don't do anything, but why the trouble?

João

[Crusader]

Just being nosy here.. I understand why you would remove the bracket, but why removing the regulator, transistor and buzzer? I know they don't do anything, but why the trouble?

João

From my point of view, I was just asking. I may not remove any of them but depending on what else I was going to do to my radio extra flat surfaces to mount stuff might be available when they are removed. So I was just confirming they really were not needed. At this stage my next mods would be Haptic feedback and a slider or two.

Cheers,
Neil

[jhsa]

Thanks.. No special reason why I asked.. Just being curious

João

[whobby]

Hi fellow 9xtreme'rs

I was using my 9X with the original 8xAA batteries, not messing with the power connector low risk of inverted power connection. Now I've purchased two LifePO4 bat's to use on the TX. And so, I would like to make this mod, to protect my fellow companion device

I'm for sure, much more "ignorant" in electronics than João ,

and I don't want to damage my board, i like my 9Xtreme + FS-TH9XB, very much, as it does thread me very well and doesn't yell at me .... some times it does, indeed.. saying that the LIPO will explode if i don't land ASAP), but it's understandable, it is trying to protect me from the evil

So i thought of asking for your help.

I've a few of those SB5100 (from a electronic kit i purchased a time ago): http://www.diodes.com/_files/datasheets/ds30135.pdf, would this diode serve to make the reverse current protection? I've read some info about it, and seems to me that it should, but i'm not sure, as it is higher rated (more Amps -- so it would protect more???)

If the above one does not work, i understand that 1A is underrated, correct? I ask, because a local shop has this 1N5819 one available -- http://www.diodes.com/_files/datasheets/ds23001.pdf.

I'm trying to avoid ebay (as it takes like forever for my purchased to reach me -- Brazilian customs is really slow, postal service is reasonable ( )

Thanks in advance for your help/suggestions.
-wm

[jhsa]

I'm for sure, much more "ignorant" in electronics than João ,

Ha ha I guess this is a compliment

I've a few of those SB5100 (from a electronic kit i purchased a time ago): http://www.diodes.com/_files/datasheets/ds30135.pdf, would this diode serve to make the reverse current protection? I've read some info about it, and seems to me that it should, but i'm not sure, as it is higher rated (more Amps -- so it would protect more???)

That one is ok in my opinion.. It is quite big as well.. If you can easy solder it in place without shorting anything else, I don't see why it shouldn't work

The 1A diode might also work but I wouldn't use it.
João

[whobby]

I'm for sure, much more "ignorant" in electronics than João ,

Ha ha I guess this is a compliment

It is a compliment. Was intended as a nice note on what you wrote on a post time ago, sorry if my bad english lead to different interpretation:

... <snip>
Thank you for your answers

João ( the person that is an absolute ignorant in electronics according to at least one person ).
:: from viewtopic.php?f=126&t=7745&start=30#p110588

I've a few of those SB5100 (from a electronic kit i purchased a time ago): http://www.diodes.com/_files/datasheets/ds30135.pdf, would this diode serve to make the reverse current protection? I've read some info about it, and seems to me that it should, but i'm not sure, as it is higher rated (more Amps -- so it would protect more???)

That one is ok in my opinion.. It is quite big as well.. If you can easy solder it in place without shorting anything else, I don't see why it shouldn't work

The 1A diode might also work but I wouldn't use it.
João

Thanks for your tips.
-wm

[jhsa]

It was a joke..
Your English is probably better than mine

Please let us know how it goes with the diode
João

[whobby]

It was a joke..
Your English is probably better than mine

Please let us know how it goes with the diode
João

Hi,

It took me a long time to get all the bits and peaces, and mostly the courage to mess with the internals of my TX (as i've no backup at the moment ..

But, with your valuable info&help, I gathered courage and did it.

All seems to be OK, at least after scratching the trace and adding the SS34 diode, re-assembling the TX it powered up, apparently without any problem. One curiosity i've is does the diode have a correct polarity/direction to be used? If so, maybe at the first two posts of this thread we could mention it. I've tried to follow adding the striped end in the same direction as the picture at the beginning.

Is there any test i should make (that does not put the TX to much at risk, like intentionally reverse connecting a LiPO?


As i've already opened the TX i'm doing (trying at least) to add a internal FrSky DHT Module.

Thank you all, specially to you João. Bellow are some pic's of the adventure.
Regards

[jhsa]

Polarity looks correct

João

[jhsa]

You can also have a look here:

viewtopic.php?f=126&t=7987

João

[whobby]

You can also have a look here:

viewtopic.php?f=126&t=7987

João

Indeed that image would have let me do the first power up, after mod, much more peace minded

I hadn't seen (at east not on the last couple of days when i was reviving my memory on how to do the mod.
thanks.

I may ask for additional help for my DHT install and/or config.

-wm