After successfully bringing 4 quads back to the future with your help I'm asking again  It is the last one, a Code Red designed 3" racer using 1000 mAh 4s packs.
I will be replacing the FrSky XSR Rx with a Radiomaster ELRS-RP3-V2 RX (the twin antenna version) and maybe the VTX.
The FC is a Lumenier Micro LUX F4 V2 which I just reflashed to BTFL 4.4.3 LUXF4OSD so that is great.
ESC is a Lumenier 25Ax4 OPTO 2-4s BLHeli_S
VTX is a Lumenier TX5G2R 200mW ((changed to TBS Unify Pro 5G8 V3))
 
1. Replacing the The ELRS Rx looks easy, connect to GND/+5V/TX3/RX3 (or TX6/RX6 ?) on the FC. 
2. But I am really confused about the VTX arrangement on this quad. Note: I read that this FC did not have a good OSD. Maybe that is why in this old quad we have battery power coming from the FC to a 12V Pololu which powers the VTX and camera (Foxeer Arrow V3) with a blue (VSEN) wire going to the camera, which is messy because the VTX could have run on 4s power, its operating voltage is 7-20V, and the FC has 5V out, so no need for Pololu? Anyway this is where I think a component change might be in order. But I have never built a ELRS Rx version all my others have Crossfire. So I don't know which VTX would work with this FC and camera to give me SmartAudio with all of the OSD choices like RSSI, LQ, batt total and cell, flight time, modes, etc. It looks like this VTX (camera) only gets voltage to display, nothing else. If I get a VTX with a SmartAudio wire can I simply connect it to either TX3 or TX6 (whichever one I don't use for the Rx) and get SmartAudio? Any recommendation then?
Oh yeah, this FC has buzzer pads, which I used for a remote buzzer. Can I use motor beeper instead with this ESC? It was running DSHOT600.

you can choose uart 3 or uart 6 for elrs
enable telemetrie, you will getvall the infos

your vtx need to support smartaudio or tramp protocoll, you can connect it to a tx on your fc and controll it over betaflight osd.

OK that sounds pretty straight forward. Any UART is as capable as another. I just need a VTX that can support SmartAudio. The camera is OK as is.

I got a TBS Unify Pro 5G8 V3 VTX. The manual says to connect it to a regulated 5V it also says "connect to converter with proper LC filtering!". Do the 5V pads on an FC (Lumenier Micro LUX F4 V2 in this case) satisfy this requirement? I'm also going to post over on the FC forum some general questions about connecting to FC power...

(27-Nov-2023, 10:17 PM)husafreak Wrote: …
Oh yeah, this FC has buzzer pads, which I used for a remote buzzer. Can I use motor beeper instead with this ESC? It was running DSHOT600.

You probably can, you also can probably customize the start up chime sequence. I’ve got most of my drones set for the ‘Imperial March’ from State Wars
In my experience using the motors as a beeper is ok for signaling status while in the house or setting up at the bench but it isn’t so good for Locating. I recommend keeping the buzzer unless you’re only using it indoors. Just my opinion.
I think betaflight has a feature that silences the beeper while the FC is connected to your computer.

Thanks @Hex. I got that advice from another forum member too. Motor beepers are nice but can be pretty feeble, and it's hard on the motors if you try to make them loud. I've been getting more into small quads and they get lost in the hedges pretty easily, need a dedicated beeper.

   

This one taught me about the Betaflight Configuration page board and sensor alignment feature, LOL. I put the board back in differently by accident after a bunch of soldering new connections, obviously, it did not fly, it did really scary stuff. So I took the quad apart and turned the board manually, but it still didn't fly right! I finally realized I could change the settings in Betaflight (no matter what direction the arrow on the FC pointed) by looking at the Setup page and get the board to transmit the correct instructions to the ESC. Voila! It flies! And it only cost me one set of props  How someone could go so long without ever figuring out how that BTFL feature works is a mystery. I will never stress over board orientation again


Added: I never thought about how the preview quad in the receiver page does not show the actual orientation of the FC the way the quad in the Setup page does. Something to be aware of.

I flew it today with the "Supafly Freestyle 3/4" tune preset" and it flew good, really sharp and quick response. But way too heavy. The smallest 4s packs I have right now are 1350's and so the AUW was 334g, for a 3" quad. Cut thrust and it drops like a rock. Gotta get some 850's. I'm glad I changed the VTX to Smart Audio, it's nice having the same OSD in all my quads.