Reverse polarity mod on plain 9x.

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Rad
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Reverse polarity mod on plain 9x.

Post by Rad »

Hi guys, I fitted the diode in the small green PCB of my 9xtreme radio years ago, but I wonder if, for a radio with no 9xtreme, the diode needs to be fitted on the same place. Yes? no? Maybe?

Thanks, lol.
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bob195558
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Re: Reverse polarity mod on plain 9x.

Post by bob195558 »

Er9x on 9x radio, with Smartieparts Programmer and TelemetrEZ Board.
ErSky9x on Taranis, Sky9x, 9Xtreme radios.
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Re: Reverse polarity mod on plain 9x.

Post by Rad »

bob195558 wrote: Thu Jul 02, 2020 10:19 pm Maybe this will be helpful: https://openrcforums.com/forum/viewtopi ... 126&t=7745
Hi, yes, that is what I did in my 9xtreme radios. I just wonder if it is the same when using the plain 9x.
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MikeB
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Re: Reverse polarity mod on plain 9x.

Post by MikeB »

Yes you may add that diode, or better the MOSFET version shown on the linked thread.
With the diode, the voltage to the 9X will be lower by 0.3 to 0.4V than the battery. The lower voltage will be the voltage displayed.

Mike
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Re: Reverse polarity mod on plain 9x.

Post by bob195558 »

Mike, should he leave the beeper as he has mostly a stock 9x radio ?
(no sound card so would loose the beep sounds with there info)


Switch Board removed Components.jpg
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Re: Reverse polarity mod on plain 9x.

Post by Rad »

Definitelly plan is to leave the beeper. This radio is not for me but a friend of mine, so it is always better to have a beeper than nothing.

About the mosfet, according to that thread, is this the one? https://www.aliexpress.com/item/3288405 ... hweb201603_

And how do I wire it? The diodes had only two legs and this I dont know how to wire it.
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MikeB
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Re: Reverse polarity mod on plain 9x.

Post by MikeB »

Yes, that's the one. A MOSFET has 3 connections: Gate, Drain and Source (G,D,S). These are labelled on diagram on the other thread. Do a search for FQP27P06 and you will find an image (and/or a datasheet) that shows which pin is which.

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Re: Reverse polarity mod on plain 9x.

Post by bob195558 »

Er9x on 9x radio, with Smartieparts Programmer and TelemetrEZ Board.
ErSky9x on Taranis, Sky9x, 9Xtreme radios.
3D-Printing: (https://openrcforums.com/forum/viewforum.php?f=129).
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Re: Reverse polarity mod on plain 9x.

Post by Rad »

Hi Mike, bob, thanks for the links. I have been studiying them for a while, but I am sorry to say I am still unsure of where to solder the mosfet legs. could you put the letters of the mosfet legs over this picture? That way I will know how to do it
Image
That is the only way I can understand it, lol
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jhsa
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Re: Reverse polarity mod on plain 9x.

Post by jhsa »

As far as I understand it, I would do it like this on an original Turnigy 9x board without upgrade boards.
Mike, does this look right?

Thanks

João

EDIT: And perhaps I would put another one on the Charging circuit too. :)
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Re: Reverse polarity mod on plain 9x.

Post by Rad »

jhsa wrote: Sun Jul 05, 2020 2:25 pm As far as I understand it, I would do it like this on an original Turnigy 9x board without upgrade boards.
Mike, does this look right?

Thanks

João

EDIT: And perhaps I would put another one on the Charging circuit too. :)
Lol that diogram is what I needed, thanks!

What happens where I had a diode on the 9xtreme? Do I remove it and I put a wire now?

Where is the charging circuit and how do I wire the mosfet there?

I am using two 18650s so not sure if that will be needed but still...
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MikeB
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Re: Reverse polarity mod on plain 9x.

Post by MikeB »

Hang on, I'm not sure the diagram from João is correct. The gate is OK, but I would put the drain to the right of the existing cut (to the switch) and the source to the track leading the the connector (pin 3).

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Re: Reverse polarity mod on plain 9x.

Post by Rad »

MikeB wrote: Sun Jul 05, 2020 7:11 pm Hang on, I'm not sure the diagram from João is correct. The gate is OK, but I would put the drain to the right of the existing cut (to the switch) and the source to the track leading the the connector (pin 3).

Mike
So, do we wait until you confirm us, right?
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Re: Reverse polarity mod on plain 9x.

Post by bob195558 »

I am not sure,
but I think Mike is suggesting this for the MOSFET connections.
MOSFET on Switch Board_G.jpg
Added Note update: do not use this MOSFET connections with the 9Xtreme board.
Instead use this way: https://openrcforums.com/forum/viewtopi ... 126&t=7745
Last edited by bob195558 on Tue Jul 14, 2020 8:07 pm, edited 3 times in total.
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jhsa
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Re: Reverse polarity mod on plain 9x.

Post by jhsa »

MikeB wrote: Sun Jul 05, 2020 7:11 pm Hang on, I'm not sure the diagram from João is correct. The gate is OK, but I would put the drain to the right of the existing cut (to the switch) and the source to the track leading the the connector (pin 3).

Mike
Mike, I think the connections I posted are correct.. The Mosfet should be a P-Channel Mosfet. Please have a look at the picture below.
The battery voltage comes in to the middle pins of the switch right? Then battery will turn the radio ON if the switch is set to the right? And off when the switch is set to the left, which also connects the charging port to the battery (middle pin) right?
By placing the Mosfet before the switch we are protecting both the radio and RF module circuits. If the Mosfet is placed where suggested for the 9XT, it will only protect the radio circuit. Could you please confirm?

Thanks

João
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Re: Reverse polarity mod on plain 9x.

Post by MikeB »

My concern was whether the charging function would still work with the MOSFET in that position. Also I was checking that power will come on when the trainer jack is connected.

I think both are OK, so those connections should be OK.

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Re: Reverse polarity mod on plain 9x.

Post by Rad »

MikeB wrote: Mon Jul 06, 2020 3:26 pm My concern was whether the charging function would still work with the MOSFET in that position. Also I was checking that power will come on when the trainer jack is connected.

I think both are OK, so those connections should be OK.

Mike
Oh cool. I should receive the mosfets along the week. Due to I already have that track cut in my 9xtreme I think I will take Bob's approach, and in my friend's radio we shall see.

I have never used the charging function with our radios. Is it safe to charge 18650s cells with that side charging plug? Is there something else that I should consider?
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Re: Reverse polarity mod on plain 9x.

Post by jhsa »

MikeB wrote: Mon Jul 06, 2020 3:26 pm My concern was whether the charging function would still work with the MOSFET in that position.
Yes, it will because it will polarize the Mosfet normally with the positive entering the source, but it will blow if the charger is reversed, that is why i suggested a protection on the charging circuit.
Also I was checking that power will come on when the trainer jack is connected.
I think the trainer power doesn't pass by the switch board? That means that if the battery is reversed and one inserts a trainer connector, the radio will also get destroyed.. This Mosfet should really be placed right after the battery connector, on the back board. :(
I did design a switch board for my radios with all sorts of protections, one of them being that the radio wouldn't turn off if the power switch failed :)
I believe the forum user Andrewju also designed and produced some switch PCBs based on this circuit.. I don't know if he still has some.

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Re: Reverse polarity mod on plain 9x.

Post by Rad »

bob195558 wrote: Mon Jul 06, 2020 12:58 am I am not sure,
but I think Mike is suggesting this for the MOSFET connections.
MOSFET on Switch Board_G.jpg
Hi, I tried this in the plain 9x and worked fine! :D

Then I tried it in my 9xtreme, and does not work good. The radio seems to be fine and everything works, but when I switch it off it does not power off.

Can somebody guide me here? That 9xtreme radio is my main radio and I need to have it working as soon as possible!
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Re: Reverse polarity mod on plain 9x.

Post by jhsa »

On the 9xtreme use the diode exactly as shown on the 9xtreme mods thread.. Not the Mosfet..

viewtopic.php?f=126&t=7987

The 9xtreme has a complete different power circuit.

João
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Re: Reverse polarity mod on plain 9x.

Post by Rad »

jhsa wrote: Tue Jul 14, 2020 1:34 pm On the 9xtreme use the diode exactly as shown on the 9xtreme mods thread.. Not the Mosfet..

viewtopic.php?f=126&t=7987

The 9xtreme has a complete different power circuit.

João
Oh, great to know. Will do immediatelly, thank you very much!
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