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Mikado V-BAR Mikado V-Stabi/V-BAR Flybarless System Software and Hardware Support


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Old 06-30-2014, 09:20 AM   #41 (permalink)
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Default Mini vbar servo brown out

Thx. 500 size heli, micro servos.
I am wondering if I am reading the units prefix correctly, as the caps I bought are micro farrads- 4.7, 10, 22, all are 35v rated. You and vstabi are referring to 4700 micro farrads, etc?
Here is the 10uf I got, but mine looks different than the picture, longer and skinnier, the one pictured is more stout. http://www.radioshack.com/product/in...ductId=2102509
I am having no issues, but for $1.50 and a few minutes, it seems too easy to not do it, if it may ever prevent a problem.
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Old 06-30-2014, 09:44 AM   #42 (permalink)
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4700F, 4700 micro Farads, yes. The first one I tried from RS looks like it was this one:

http://www.radioshack.com/product/in...lue=RadioShack

But this was comparatively bulky, due to the 35V rating. Going to 10V rated units made them a lot smaller for the same capacitance.

What BEC are you using? If it's a WR or something similar, the likelihood of needing a cap is lower. If it's the internal BEC on a Castle Ice/Edge ESC, on the other hand, I would be more inclined to use one, even if you passed the brownout test.

I had a setup that was totally fine. Then I had a servo start failing in-flight. I was lucky enough to get the heli down in one piece, but as I was walking over, I'm pretty sure my FBL reset (wasn't a VBar), I suspect due to the bad servo drawing more current than usual. It's certainly not something that *should* ever happen, but things can cause you to suddenly draw more current than typical.
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Old 06-30-2014, 09:57 AM   #43 (permalink)
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Default Mini vbar servo brown out

I'm using the hobbywing 60A, stock atom 500 esc/bec.
I will get appropriate caps.
My only experience with adding a capacitor is with automotive subwoofer amplifiers. Very notable performance boost. If any of the power reserve applies to my servos, I'm in.
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Old 07-25-2014, 10:00 AM   #44 (permalink)
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So what is the verdict on which cap to get? Is the best 6800uF at 10Volts?

I'm having the same issue, I'd like to try the cap method. If I can't find that exact size, what ranges are acceptable?
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Old 07-25-2014, 10:23 AM   #45 (permalink)
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I'd expect it's influenced by your servos, BEC, and heli.

My capacitance (10V 6800uF) worked for my particular setup. Smaller gave me intermittent low-voltage warnings.

If it were me, and I had to pick a different size from my 6800uF, I'd prefer to go a little larger, vs a little smaller. As far as I understand it, there is no real need to go higher than 10V on the voltage rating. But going somewhat higher on the capacitance (eg- 10,000uF) is probably fine. There must be a point where too-big makes things worse again, but I'm hoping that would be a much-much larger capacitance than what's being discussed.

Whatever you use (even if it's no cap), I'd suggest a rigorous bench test before flying, to be safe.
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Old 07-25-2014, 06:53 PM   #46 (permalink)
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OK, I managed to find 2 16v 3300uF caps I plan to use in parallel to add up to 6600uF.

Do these have to be put on a servo channel, or can I use RX?

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Old 07-25-2014, 07:08 PM   #47 (permalink)
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I don't know what good sources there are in Canada, but I bought mine from Digikey, just FWIW. Massive selection, and I thought the prices were good.

Ideally I think you want the cap as close to your load as possible. If, for instance, you had it on the RX, then extensions from the RX to the FBL, then servos from there, that would have more resistance between the cap and the load (servos) vs plugging it into an available port on the FBL.

I am using sats on my VBar, so no RX. I put my cap on a Y-cable from the FBL, with my tail servo on the other lead of the Y-cable.

I debated putting it on a Y-cable with the external BEC, but wasn't comfortable adding more connections between the critical BEC, and the FBL.

With all that said, the simplest thing, involving no added connectors, is just plugging it into the RX, if using one. Bench test it; if it passes, you're probably OK.
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Old 07-26-2014, 10:40 AM   #48 (permalink)
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Default Re: Mini vbar servo brown out

Thanks for the info redOctobyr.

Because I don't have an RX I guess I will need to make or get a y cable.

Actually I did the pitch pump test. I set pitch pump to 100 and moved collective as fast as possible for a minute. I never got a low voltage signal after doing this test twice, so I'm beginning to wonder if I really need this cap, or I have other issues.

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Old 07-26-2014, 11:05 PM   #49 (permalink)
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"To Cap...or not to Cap"....

Sorry, I'm not about to risk my $3000+ heli on a ten cent solution.

fwiw
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Old 11-20-2014, 08:13 AM   #50 (permalink)
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Quote:
Originally Posted by newbheliusr View Post
I use a 4700. And I would be happy to make one up for you and send it to you.


Sent from my iPhone using (***WARNING*** Stop Spamming Helifreak)
Can you plug a 6800 16v cap into an open sbus slot? All my mini vbar slots are taken.
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Old 11-20-2014, 08:17 AM   #51 (permalink)
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Anything that can accept incoming power should be ok. Not the special 'RXA' port, for instance.

Sent using Tapatalk.
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Old 11-20-2014, 08:21 AM   #52 (permalink)
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Quote:
Originally Posted by RedOctobyr View Post
Anything that can accept incoming power should be ok. Not the special 'RXA' port, for instance.

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Thanks very much.
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