RSSI pins for various receivers - Page 22 - RC Groups
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Dec 04, 2011, 08:00 AM
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i put a 170k ohm set of resistors in series with a capacitor(47uF) and it seems to be working. getting nice slow readings on the output. takes 1-2 seconds to change .01v(i need 10uF... 47uF is too slow)
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Dec 04, 2011, 09:47 AM
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flylite's Avatar
Originally Posted by chatch15117

you can just use the capacitor on the board. trace the 7th pin to some capacitor and tap it

looks like your pin isn't even being used... unless there's more from a different angle
Guys I have R128DF which has the same chip as this - Can I take it that this also will pipe out RSSI?
I'll upload a pic if you need.

Dec 04, 2011, 04:25 PM
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yes the second page of the thread says any 7761f chip will work on the 7th pin

Originally Posted by RENATOA
For anyone asking for RSSI for unknown receivers:
- open it
- try to locate chips like 7761 or 31136, 99% of the FM receivers (35/40/72MHz) use such chip
- some pictures of the two chips below:
- RSSI is on pin 7 of 7761, or pin 12 of 31136

If the above fails, first search rcg archive using "rssi <your receiver>"
If fails again, try Google
Finally, ask here, but always post pictures !
Dec 05, 2011, 03:03 AM
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my range is very small... 0.23v to 0.25v. maybe i need more than 170k ohms?
Dec 09, 2011, 02:59 PM
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bamabaxter's Avatar
Found an easier and still reliable tap point for RSSI on the newer Corona RP8D1. Here is a picture. Make sure that a voltage follower or a 10K resistor is used at the minimum. I get ~1.7V full strength and ~0.8V weakest. Hope this helps. Remzibi's way works well, but this is just a little easier.
Dec 09, 2011, 05:57 PM
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Last edited by 999vertigo; May 21, 2012 at 07:29 PM.
Jan 13, 2012, 07:07 PM
Power-line attraction pilot
Has anyone actually successfully gotten the turnigy 9x receiver to output a useful rssi value and used it with an osd??? Bakchos never actually got it working.
Jan 18, 2012, 11:16 AM
Registered User
Originally Posted by Freedom35
I found this image at a Russian R/C forum (here:

Attachment 3205801

And I gave it a try. The pin selection is a header between the two boards, so I used the other side for convienence sake. I read 560 mV max and 145 mV min. I hope RVOSD can calibrate to such a small swing.

Attachment 3205802 Attachment 3205803 Attachment 3205804 Attachment 3205805 Attachment 3205806 Attachment 3205808 Attachment 3205809 Attachment 3205810



First, I apologize for the bad translation. I do not speak English and I communicate with Google translation.

I just made adding the RSSI Pin. I did the test with a multimeter and with the OSD Remzibi. The values ​​of 0% and 100% vary hugely.
0% = 12mV to 27mV
100% = 520mV to 565mV

Have you noticed the same phenomenon?

In the photo of the Russian site, the second is interresting. If the translation is correct, it is the red LED. The output shows the packet loss. Can we also add the signal to the OSD remzibi?

Thank you for the tutorial.

Jan 18, 2012, 01:30 PM
Power-line attraction pilot
Originally Posted by caall99
Has anyone actually successfully gotten the turnigy 9x receiver to output a useful rssi value and used it with an osd??? Bakchos never actually got it working.
Bumping this. I assume there are a lot of people interested, but not forward enough to ask for proper guidance.

Jan 18, 2012, 01:56 PM
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Id like to hear exactly how to make that rssi buffer, exactly which components to use...
Jan 18, 2012, 02:35 PM
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bamabaxter's Avatar
Originally Posted by msev
Id like to hear exactly how to make that rssi buffer, exactly which components to use...
Jan 18, 2012, 06:10 PM
sfakias's Avatar
Originally Posted by caall99
Has anyone actually successfully gotten the turnigy 9x receiver to output a useful rssi value and used it with an osd??? Bakchos never actually got it working.
Originally Posted by bamabaxter
Hi all.

I am puzzled as well because after doing lots of research I was not able to find a post including a straight forward working solution for displaying the Turnigy 9X RSSI with ET OSD pro, since both of these products are quite common.

I did add a RSSI out pin on my rx by connecting the RSSI pin of the TGY 9X rx according to Bakchos' post. The results were not as expected, since the RSSI value displayed was fluctuating way too much (about 100% to 40% with the tx sitting next to the rx)

Then, I did built the RSSI buffer using the LM358 according to BlueAngel2000's post, but that did not improved the situation, since the same fluctuations were evident.

Time for a disclaimer here: I am not very familiar with the theory or practice of electronics. I am slowly building my knowledge on the subject and what I usually do up to now is trial and error (read:magic smoke). My comments below could well be totally wrong - the input from electronically educated people is desired and welcomed.

Then, I did built a PC oscilloscope and checked the RSSI output of the LM358. The output puzzled me even more, but I do not have the background to explain it: The LM358 outputs some form of pulse waveform voltage, and not a constant voltage (always tx sitting next to the rx). It seems to me that the RSSI value that the OSD displays is the momentary volt value at the time of sampling, which could be at the top of the pulse, at the bottom of the pulse, or anywhere in between. Maybe some form of R-C circuit could be used to smooth out this pulse, but this just an uneducated guess on my part. Does RSSI outputs digital signal, but the OSD expects analogue signal?

To complicate things even more, and confuse my uninformed self, the amplitude of the volt output pulses that is displayed in the PC oscilloscope, is great the moment I connect the LM358 to the oscilloscope probe, but it constantly decays with time, and after 3-4 sec the oscilloscope display shows effectively a flat line, until I disconnect and reconnect again when this decaying pulse is again shown. I suspect that this behaviour has to do more with how the pc oscilloscope works than whith what the TGY9X rc RSSI pin really outputs.

Then, there is the red LED solution that could be a better approach, but I have not tried it yet. I am aware of the RCexplorer tutorial on how to do it on a FASST rx, and the relevant thread by reely340. I suppose it could be done in a similar way with the TGY 9X (please advise).

Please show understanding if the above post is not very clear the first time you read it, I am writing in a language that is not my mother language, and I am writing about electronics, that I do not understand well.

However, it would be GREAT if this post makes knowledgeable members (and there are a few) to cooperate in order to come up to a working solution for TGY9X RSSI with ET OSD pro. I bet that there will be many, many people that will be grateful for that (myself included)!

Best regards,
Jan 18, 2012, 11:29 PM
Registered User
Just did the rssi mod to my FS-R8B. Let me just say, wow thats small. It's been a while since I've soldered something this small. Got it all done though and it looks great.

With the transmitter off I get .8 volts, with it on and the tx right next to the rx I get 1.050volts avg. The number then goes up the further away I place the tx. Haven't tried the microwave trick, but when I do I'll post the numbers.

With this mod I'll be able to hold off on the FRSky telemetry setup for my 9X for a little while. In a week I'll be able to plug this into my OSD and see what it does.
Jan 19, 2012, 02:12 AM
Registered User
With pulsed rssi signal you need to make a low pass filter.
You can increase value of both to increase filtering.
If you are not using a buffer, I would recommend a high R value ( >100kohm)
Jan 19, 2012, 06:07 AM
Registered User

Who can tell me why my RSSI value varies from 0% to 17% when the radio (transmitter) is off?

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