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What could possibly go wrong? (Powering FPV Camera & VTX from radio RX battery)
#1
OK, so I've been involved with FPV long enough to know that it's generally advised to avoid doing what I'm about to propose.

Specifically, I'm asking for input from those who have experience running their FPV camera and video transmitter off the same battery that powers their radio receiver and servos.

Yes, I know... read the first line again.

The reason for this question is the somewhat unique use case I want to explore for a FPV rig:

Specifically, I want to further explore FPV slope soaring, and I live in a place where my best / favorite soaring site requires the use of very lightweight gliders. VERY lightweight... think 1.2m (48") wingspan weighing around 350g (12oz) all up, including battery.

Running a separate FPV battery wouldn't be the end of the world, but if there's any way I could avoid it, I'd prefer to.

I've found the Lumenier 200mw AIO FPV camera & VTX package thanks to a recent Charpu video where he used one on a 2" quad. It weighs only 4.5g, will run on 3.3 - 5V, which should be well within the range of a typical 4.8V receiver pack, especially if I used a small Pololu voltage regulator to ensure I never went above 5V.

Now, my thinking is this: Quads run everything off a single battery pack, and those motors must certainly generate way more noise than a few servos... am I way off base here?

Obviously I'll need to carefully monitor pack voltage to ensure I don't get brownouts on my radio system (yay Spektrum!) and blackouts on my video system. But that's easy, and the glider I have in mind will make switching batteries in the field no big deal.

Am I way off base here? Would appreciate a sanity check.

P.S. - I do tons of LOS slope aerobatics and want to explore / potentially help pioneer FPV slope aerobatics. Here's a sample of what I'm talking about, including the glider - Dream-Flight Ahi (1.2m / 350g) I plan to try flying FPV with.

#2
Sound right to me, as far as I know most of the 'noise' in the fpv feed is from back EMF from the motors, but I think I have read somewhere that the 'Damped Light' (active braking of the motors when reducing throttle) can cause large voltage spikes too. I have never flown anything with servo's before so I don't know how much noise they may introduce, but I'm pretty certain that it's not going to be anywhere near that generated by the motors.

The consumption of this Luminier AIO (not sure if this is the exact one you were looking at?) is 500mA at 3.2-5v which means that you could get over half an hour of FPV from a separate 300mAh battery that weighs about 9 grams. As I understood from your other posts that you add ballast to the nose of the slope gliders, could a separate battery and the AIO camera provide this ballast? Or do you think that it might just make it difficult to get the CG right and expose the camera to damage?
Windless fields and smokeless builds
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#3
You'll be fine.

If your receiver can cope with the spikes that your servos cause then so can the AIO FPV camera!
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#4
Thanks for the replies!

Here is the actual Lumenier AIO I'll be using:
http://www.getfpv.com/fpv/cameras/lumeni...tenna.html


Claims a maximum consumption of 350mA, presumably that's at 3.3V and 200mW transmit power.

This is what Charpu was able to do with the thing, on a 2" quad:


Assuming my glider is electronically quieter than a 2" racing quad (lol!), I am hopeful it will give at least an OK picture. I have flawless, crystal-clear views well beyond 250m with my 100mW Fatshark transmitter from 5 years ago (still running strong) using a CP cloverleaf on the VTx and a skew planar wheel on the VRx on my FPV-converted Radian, so I'm hopeful that I can run the Lumenier AIO at 50mW or maybe even 25mW on my aerobatics glider and get better run times.

@Tom, we do have to add ballast to the nose, but the way our modern gliders are designed, they'll balance using a 700mAh 4.8V 4S iMH pretty perfectly. My theory is to switch that for a 700mAh 6.6V 2S LiFe pack (or possibly a Lipo) and make up the difference in weight between the heavier NiMH and lighter LiFe using the FPV camera, VTx and BEC/voltage regulator. My "back of the envelope" calculations indicate the AIO plus a Pololu will be pretty close to the difference in weight between my current 700mAh NiMH and the LiFe pack I typically use. The LiFe has a nice flat discharge curve, too.

The real question is how the heck I'll wedge a pan and tilt into my glider Big Grin

Brand new video from a recent trip to the Alps. FPV in this setting would have been hallucinogenic!
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#5
If you're going to use a small regulator to provide power to the cam/VTX, you should get crystal clear video. As long as you keep wires away from interference sources and all that stuff you already know.

You have a much more friendly electrical environment on a glider. To say that quads are a noisy environment electrically is putting it far too mildly. "Downright hostile" is probably more accurate!
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  • Tom BD Bad, RENOV8R
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