Hi everyone!

So I'm very new to this hobby but am loving it. I just built a new mini quad (Armattan Chameleon) with an Omnibus F4 Pro FC, Armattant PDB V3, FrSky XSR, and originally a TBS Unify Pro VTX.

After my first couple of flights my VTX would only give me video if I was pointing straight at it and within a couple feet. I thought I messed up the UFL connector so I had a spare unify pro I swapped for. Same issue happened. I ensured I powered it via a 5V pin as I had to bridge RAM to VCC for full 4S to camera as camera wouldn't produce an image (Omnibus was putting out 4.43V when bridging RAM to 5V so I had to use 4S.)

Because the unify pro only supports 5V I used a spare 5V on the board. The board is rated to supply 5V 3A.

After the second unify pro stopped working I swapped it out for my Aomway 200mW VTX. To use the Aomway I had to solder leads to the RAM pin to get full 4S as it needs at least 7V.

The Aomway worked for quite a while. I actually don't know if it died from a wreck or not where I noticed too late that the SMA male tip broke off. Maybe it over heated without that small piece, but it stopped transmitting altogether. I tried a new antenna on it and confirmed it is done.

The one thing that concerns me, and why I came here to you all and tell this to ...is maybe it's back current from active braking from the ESCs? I was running it pretty hard to see how it performed. I did some 5-10 second punch outs. In blackbox I notice during those punch outs that it couldn't record anything (just missing data for those blocks.)

Any thoughts? How do I keep from eating up VTXs? (I'm also worried that maybe the Omnibus BEC cannot handle the active braking ...and I have Lipo positive lead going into Omnibus FIRST in order to use the FC's onboard current sensor.)

Thanks in advance!

You are right, reason is most likely voltage spikes fed back from the escs.

Best tip is to fight them at the source: put low-esr caps on escs, or on pdb. There's also filters to smooth voltage between power source and video gear, usually called lc-filter (if you're an audiohead: lc does not mean low-cut in this case - it stands for a spool and something else i don't remember).

PS: there's a good video of a guy testing this with littlebee 20a escs on 4s - voltage spikes went up to 30V if i remember right.

(27-Feb-2017, 09:47 PM)fftunes Wrote: You are right, reason is most likely voltage spoikes fed back from the escs.

Best tip is to fight them at the source: put low-esr caps on escs, or on pdb. There's also filters to smooth voltage between power source and video gear, usually called lc-filter (if you're an audiohead: lc does not mean low-cut in this case - it stands for a spool and something else i don't remember).

PS: there's a good video of a guy testing this with littlebee 20a escs on 4s - voltage spikes went up to 30V if i remember right.

Awesome! Thank you. I guess I'll install the low-esr cap where the Lipo connects ...before the shunt on the FC for positive and then on the ground on the bottom side of the FC.

Do people put a cap on each of the ESCs?? Or just by the Lipo connection?

I'll look into LC filter too. I ordered a Diatone SP2 ...i wonder if it has a built in LC that will also help.

Thank you for your reply!!

4x470uf capacitors on all my 5" quads. one on each esc

Let me reply like that



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I use 1000uf low esr cap (panasonic) 16v. I know the voltage is not high enough, but none of them failed on me yet and it seems to be working very well.

Thank you all. I just ordered some 1000uF 25V and 330uF 25V caps. I figured I'd try to see how it fits either putting 330 at the ESC or 1000 at the Lipo connection source.