What's the best practice on wiring in the minimosd micro? My vtx has no separate ground for the video (or audio). When I wire the camera, I'm using 12v reg for it. Should I have the black wire from cam also hooked to the regulator? Then just run the yellow video wire in and out of the osd? Right now I have the camera black and yellow to video in on osd, and only yellow on video out to vtx.

I got myself confused on grounding practices basically. It works the way it is now, but I've heard of ground loops and I'd like to avoid one...even though I'm not sure what they are . Is the ground coming from the camera for the power, video or both? Should I "Y" off the camera ground and run it both to osd and regulator?

Thanks for helping me get the cotton out of my head.

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Forgot I made an LC filter too. Here's a sloppy sketch of how I currently have it wired.

I think a better practice would be to create a common ground

Ground loops are simply what the name suggests - a possible loop in ground wiring ie. when You connect camera ground to both the PDB and VTX "video ground" (which is the same ground BTW) and then VTX to the PDB ground. So a very small current can be induced and flowing trough a loop like: camera -> VTX -> PDB -> camera -> and so on. That's why using a single ground is recommended.

The simplest way to avoid that is remembering that every component has just one ground (and if You are not sure, do a continuity test with a multimeter) and to connect every used ground cable into a PDB pad/pin (or other power source) and not using excess connections like additionally grounding video signal or - another example, a vbat pin on the FC where only + is needed and 1 ground for the whole board (yes, You can ground the FC on vbat pin and that is enough).

There are some exceptions on the ground rule - ESCs for instance sometimes behave badly when "signal ground" is not connected (which is also the same ground as "power ground"). Can't explain that, as I'm no electrician my understanding of this topic is limited. "Just a single ground" rule works on all my FPV systems flawlessly though.

OK thanks guys, I think I'm good now. Eventually my osd stopped working. It started dropping the overlay on throttle punches. Thinking it was an ground issue I wired the vid in out ground (in from camera, out to tx). Plugged in lipo and had no signal at all. I think I fried that osd in the process too. Lucky for me I had ordered a spare and it came in the mail yesterday.

That's when I learned the overlay drop issue is commonly seen when powering the osd from the FC. So I just unsoldered the + from the UART and hookednit directly to 5v pdb. Left everything else the same and its all good now!


tl;dr.... Best practice is to get 5v from a dedicated regulator. The minimosd is very sensitive to fluctuating voltage. And ground camera to vtx through the osd if you still have issues.

Yes you are right, the overlay disappearing is due to voltage sag... which introduce noise in your 5V... (minimosd is extremely sensitive to noise in power)
I found a good LC filter or PDB could sort this out... I am using Demon Core and never had any problem with it...

OK, another issue has cropped up. Finally got my quad flying well after having some random rolls after a pitch. Guys on betaflight thread helped. BTW, raising min_throttle to 1060 (30 over where my motors spin) took care of the death rolls.

Flew 3 packs and had a great time. Then another video issue crept in . If u do any hard pitch or roll, the video goes to snow. I can still vaguely make out the horizon so I haven't crashed. It comes back in 2 seconds. Even if I flip the stick and let it snap back to center, it will do it.

Thought it was a loose cable, figured easy enough I'll just tap things and see what's loose. But with motors off I don't get a single glitch. BUT, if I arm the moyors (motors spinning) and tap the quad on the ground it will drop the video.

Also if the video doesn't cut out entirely, it will get real bright like its over exposed. Sounds like a camera problem, but why its perfectly fine when the motors are not spinning has me stumped.

So, I'm probably going to redo it all again. I'm half tempted to put a separate regulator for each device. I just got 4 adjustable in the mail. The camera is the only thing on 12v on the pdb.

Next build I'm gonna try an all in one pdb with osd for sure. If the rrosd wasn't sold out I'd get one now. Any one know another reliable pdb with osd?

(13-Apr-2016, 04:38 PM)Bandook Wrote: Next build I'm gonna try an all in one pdb with osd for sure. If the rrosd wasn't sold out I'd get one now. Any one know another reliable pdb with osd?

I like Quadrevo PowerOSD Pro.  It has filtered 5V and 10V (not 12) out.

You can try supplying 5v to the OSD from the VTX. Works perfectly on my aomway (with all devices grounded on PDB directly)

(13-Apr-2016, 07:09 PM)Konrad Stepanajtys Wrote: You can try supplying 5v to the OSD from the VTX. Works perfectly on my aomway (with all devices grounded on PDB directly)

I think I'll try that, thanks. I forgot I had swapped in a new vtx and it has the 5v out. Old one didn't. The issue with the video dropping must be a bad solder joint, only thing I can think of. I'll clean up all my joints and try again. I like tinkering around on the bench...but the weather has turned nice and now I just want a reliable quad lol. Once I get this one nailed I can rebuild my old quad for a backup.

Well, I rewired my camera and vtx. Took out my homemade LC filter I had hooked to the camera. Went for a fly this morning and issue is still there. But m pretty sure its the minimosd AGAIN lol. I found it dropping the overlay sometimes but not always. Sooo, I'll rewire the osd and try again. I'd remove it if it wasn't for the stick tuning feature. I can time my flights now. But osd tuning is so sweet.

On the bright side, I was still able to fly 6 packs. Just had to be more careful with the right stick, if I flicked it video cut out. But I am loving rewrite pidc with superexpo! I've never felt so in control of my quad.

Well, I got through the race this weekend. Had a couple issues where the camera bleached out or went dark and my reception slowly got worse. This was using a new Eachine 200mw vtx for the first time.

Went for another session yesterday and could only get a black screen. Turns out the new vtx gave up the ghost . Installed old vtx and a new minimosd and all is well again.

I did have one hickup where I lost reception, but I think I know what may be causing that now. During all this I found some info regarding the Quantum v2 goggles where IBcrazy is saying that an impedance mismatch with the fr632 receiver is known to cause issues like mine. I'm using the fr632.

Anyways, just putting all this here to log my issues and progress in case anyone else has these issues.

(19-Apr-2016, 03:33 PM)Bandook Wrote: I did have one hickup where I lost reception, but I think I know what may be causing that now. During all this I found some info regarding the Quantum v2 goggles where IBcrazy is saying that an impedance mismatch with the fr632 receiver is known to cause issues like mine. I'm using the fr632.

impedance mismatch between FR632 and Quantum V2??

Yeah, something about the fr632 receiver and the monitor on the V2's.

Here's the thread.

http://www.rcgroups.com/forums/showthread.php?t=2641715

At first I thought it was bad luck... Now I just think I'm an idiot Since my best quad is awaiting parts, I put my 250 back together. I flew for about 60 seconds landed noticed my antenna was loose went to tighten it with some metal needle nose pliers and shorted on my LED wires. When to take off again and my video is crap looks like I burned another minimosd. Bahahaha... I suck. Did a quick field repair to bypass it and thankfully my vtx and cam are fine.

I was gonna order the rrosd but you can't do pid tuning with it, so more minimosd's on the way...

Was thinking, it would be nice to have some kind of fuse inline. The surge likely came from the vbat connection. Some type of current limiter inline with the vbat would be smart

burning stuff is help you learn quicker LOL
I must have burned 10+ minimOSD now still learning! haha