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Strange video noise even with capacitors

#1
Hi,

I have a fairly new build and In the first few minutes of flying the video feed is really clear even at full throttle but once the lipo gets to around 18v (I'm running 5s) video noise starts to appear. This video noise only happens though at high throttle inputs and it's pretty bad. The strange thing is that even when I give a small blip of high throttle and return to hover the noise appears and stays for around 3s even though the quad is just hovering.

To tried to fix it by soldering 4 470uf capacitors directly on the escs however this seems to have made it a little worse because now there is a minimal amount of noise even at the start of the flight and once the lipo voltage gets to around 18v the noise is worse than before.

Setup:

Betaflight F4
Wraith 32 v2 escs
Hypetrain 2306 2150kv motors

Tbs Unify pro V3
Runcam micro Eagle jb


Both the the vtx and the fpv camera are powered off 5v and I soldered both the ground wires to the agnd pad, I also have isolated the sma connector from the carbon fibre.

Any advice?

Thank you for your help
 

Captain Video

Well-known member
#2
Good Morning:
I recently discovered if I have my FPV cam to close to the battery or it's power leads, you can get horizontal lines of distortion in the picture. Try moving the camera and its power leads away from the battery
 

PsyBorg

Wake up! Time to fly!
#3
Sounds like your video wires are close to something really noisy.

When I do a build I braid the three camera wires. That elliminates alot of issues as it becomes its own shielded cable.

Second on larger quads like my Alien the power wires for fc and escs stay on the lower plate and the video cables are run along the top plate.
 

Merv

Well-known member
#4
once the lipo gets to around 18v (I'm running 5s) .... Both the the vtx and the fpv camera are powered off 5v
18V on 5S, sounds like you should land soon.
Question: How are you getting 5V? Why would it work fine until your batteries get low?
 
#5
Sounds like your video wires are close to something really noisy.

When I do a build I braid the three camera wires. That elliminates alot of issues as it becomes its own shielded cable.

Second on larger quads like my Alien the power wires for fc and escs stay on the lower plate and the video cables are run along the top plate.
Thank you for your reply,
The video wires from the camera were loose and basically resting on the esc power and signal wires so I braided the wires and taped them to the top plate however with 20mm standoffs I was only able to get 1cm or who of clearance. I can't fly till Saturday so I will post an update in a couple of days.
 

Bricks

Well-known member
#9
Dumb question what is your camera rated for voltage? Some of my newer cameras and transmitter are rated 12 volts Sounds like the camera could be getting to low of a voltage as the battery sags..

One of my quads for camera power I added a JST connector and that plugs into my battery balance leads.
 
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Merv

Well-known member
#13
I have Betaflight set to warn me when cells reach 3.5 and minimum cell voltage set to 3.3
You say this only happens when voltage drops to 18V. Is Betaflight giving you this voltage or is it coming from somewhere else? If it's coming from a separate reading, is it possible that the two are giving different readings. Your seeing 18V & Betaflight is seeing 17.5V. Could the interference is from some warning Betaflight is giving?
 

Merv

Well-known member
#14
But why would it work throughout most of the battery and not work only at the end?
Could the BEC in Betaflight be switching to a different circuit @ 18V? One circuit is for 21V to 18V & switches to something else below 18V.

Could you try a different source for 5V?
 
#15
You say this only happens when voltage drops to 18V. Is Betaflight giving you this voltage or is it coming from somewhere else? If it's coming from a separate reading, is it possible that the two are giving different readings. Your seeing 18V & Betaflight is seeing 17.5V. Could the interference is from some warning Betaflight is giving?
Betaflight is getting the voltage from the from the Betaflight f4 current sensor and it's just being displayed on the osd.
 
#16
Could the BEC in Betaflight be switching to a different circuit @ 18V? One circuit is for 21V to 18V & switches to something else below 18V.

Could you try a different source for 5V?
It could be that but there is no other source for 5v apart from the Betaflight f4 because the vtx I'm using doesn't have voltage out.
 

Merv

Well-known member
#18
there is no other source for 5v apart
It may be worth you while to find another 5v source. Even if you need to install a separate battery. Try to completely separate your FPV system from the any voltage on the Quad. If the problem still exist then both @Bricks theory and mine have been eliminated. If this is a fix, then we know where to look for a solution.

Unless someone else has ideas, we need to start eliminating possibilities.
 
#19
I flew I a few packs today and the problem is still there. I forgot to mention that I'm getting horizontal black lines but only on high throttle inputs and when the battery is under around 18.6v. This might be a problem with vtx not getting enough power when the battery is lower in voltage. I will try again tomorrow and see if lowering the vtx power output from 600mw to 200mw or even 25mw makes a difference.