I've built a few "kit" quads and have seen different ways to power peripherals, the basic ones, Rx, VTX, camera. I don't think these are power hungry, (maybe that changes with HD or long range stuff). I'll use my Lumenier Micro Lux V2 as an example. It has several pads marked G, G, and Gnd. But they are all Ground. It has two 5V pads and a 3V pad. I have an ELRS Rx, TBS Unify Pro V3, and Foxeer camera. They all need 5V power. The VTX says it needs regulated and filtered power. I know the FC provides regulated power but what about filtering? So I see a lot of options, I could connect all three to one pad (GND and 5V) or I could connect the RX and VTX to different pads. I can power the camera from the VTX or from the FC. I can use a separate 5V regulator for the VTX/camera, like a Pololu or the clunky Lumenier ones that take power directly from the flight battery. What's "best practice" here?

I just realized this particular VTX only has four wires (why would TBS do that?) and I have to power my camera from the FC. But generally the question remains.

The main reason we stick a low ESR capacitor onto our battery pads is to clean up the power. As long as you're not drawing too much amperage, just use the 5V and it should be good. You'll know if the power isn't clean when you hit the throttle.

Thanks, have smaller and older quads which do not have capacitors across the battery connection. I guess I should pick some up and add them. What is "Low ESR"? Anyway I'm sure there is plenty of info online about which ones to get, sizing, etc. I know they have to be rated for the battery voltage, that's about it.

Put simply, a low ESR capacitor charges and discharges faster, so it's going to be better at soaking up the ripples in your DC voltage. Any change in the demand from your power supply will create some amount of dip or surge in the voltage, and will cause precision components to operate less optimally. As for capacitor max voltage, almost every capacitor I've used has been roughly 10-20v above the battery voltage. Gotta be able to go beyond the battery voltage to absorb a spike after all. I'll leave you with the caps I use on my models for some reference on what I've seen work.

75mm 1S tinywhoop - nothing
3" 2S ultralight - 16v 220uf
4" 4S freestyler - 36v 470uf
7" 6S cruiser - 50v 1000uf

But yeah, a good capacitor will make things like gyros and video transmitters perform much better, and everything should be a least a little happier from a stable voltage supply. The bigger and angrier your model is, the more important capacitors become.

Thanks! And FWIW I got the Camera and VTX working on this build. Due to pad placement I doubled up the Camera and Rx power wires on the same pads and the VTX to another set of pads. All is well. Just have to add a cap