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Old Dec 14, 2011, 01:33 AM
The Flying Circus
ommadawn's Avatar
Adelaide South Australia
Joined Sep 2007
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Quote:
Originally Posted by lrrps View Post
Frank,
i'm amazed that such a powerful VTX doesn't create any interference of some sort, contrarily to what I read before.
That's a good point.
Do you use a seperate battery to power the VTX ?
That is a very sore point. I dont usually use a separate battery, so I am not used to monitoring one. I added a separate 3s 1000 recently to run my FPV gear and UBEC. Wanted to see how it affected the video. After about 40 minutes flying i noticed that the Aux battery was at 9.3v and dropping rapidly and I was > 1 mile from home. I quickly woke up and headed home as fast as I could, all the time watching the V dropping rapidly, just waiting for the video to drop out.
It went flat about half a mile away so I lost video but still had RTH. This worked until i regained visual and took back control. I almost pulled off the save, but the battery went totally flat and took the Ubec with it. Plane crashed 500m away.
So NO I DONT USE A SEPARATE BATTERY ANYMORE!!!!!!!!!!!!
Cheers
Frank
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Old Dec 14, 2011, 02:48 AM
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Le Havre, FRANCE
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Quote:
Originally Posted by ommadawn View Post
That is a very sore point. I dont usually use a separate battery, so I am not used to monitoring one. I added a separate 3s 1000 recently to run my FPV gear and UBEC. Wanted to see how it affected the video. After about 40 minutes flying i noticed that the Aux battery was at 9.3v and dropping rapidly and I was > 1 mile from home. I quickly woke up and headed home as fast as I could, all the time watching the V dropping rapidly, just waiting for the video to drop out.
It went flat about half a mile away so I lost video but still had RTH. This worked until i regained visual and took back control. I almost pulled off the save, but the battery went totally flat and took the Ubec with it. Plane crashed 500m away.
So NO I DONT USE A SEPARATE BATTERY ANYMORE!!!!!!!!!!!!
Cheers
Frank
Wow, that sounds scary.
The reason I asked is because my downlink video is terrible, I got lots of interferences and at times only noise for a few long seconds, I'm running 4S with a 12V DC regulator for the video system.
I suspect noise from the main lipo pack that's why I want to try running a seperate 3S pack for the 5.8Ghz video system.
My 900 Mhz video system doesn't have this problem, go figure.
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Old Dec 14, 2011, 06:15 AM
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ommadawn,

That's what I was trying to tell Trappy some time back, that there are advantages to using two batteries.

Daniel
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Old Dec 14, 2011, 06:34 AM
The Flying Circus
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Adelaide South Australia
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Well Daniel, the only advantage I can see from this is I now have more room in my shed.
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Old Dec 14, 2011, 06:44 AM
The Flying Circus
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Adelaide South Australia
Joined Sep 2007
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Hi Gaston,
I also use a home made LC filter on the 12v supply. This probably helps. I am running 3s and dont use a regulator. When I get a chance I will post the video of the aux battery discharging and the resultant events. Its interesting to see the V dropping. The camera quits first, but OSD still displays on a blank screen and the VTX still works right down to around 7v before either OSD or VTX quits. Obviously the crash which happened 2 mins later didnt get recorded.
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Old Dec 14, 2011, 06:44 AM
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ommadawn,

And an excuse to buy more toys, stuff I mean.

Daniel
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Old Dec 14, 2011, 06:49 AM
The Flying Circus
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Adelaide South Australia
Joined Sep 2007
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I dont need an excuse! This week my Servo City gearbox antenna tracker, new Head plays, Rob38's Ski mask for the HPs, and a bonus DL rx all turned up in separate parcels. My wife thinks I have a deal with Santa. Ho Ho Ho.
Frank
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Old Dec 14, 2011, 07:03 AM
KJ4YYJ
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Saint Petersburg FL
Joined Jun 2009
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Todd: what VTx Are you using?

Birds Eye Video of Mountain Goats in a Winter Wonderland with GoPro Hero2 and DragonLink FPV

Thanks
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Old Dec 14, 2011, 07:30 AM
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Le Havre, FRANCE
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Quote:
Originally Posted by ommadawn View Post
Hi Gaston,
I also use a home made LC filter on the 12v supply. This probably helps. I am running 3s and dont use a regulator. When I get a chance I will post the video of the aux battery discharging and the resultant events. Its interesting to see the V dropping. The camera quits first, but OSD still displays on a blank screen and the VTX still works right down to around 7v before either OSD or VTX quits. Obviously the crash which happened 2 mins later didnt get recorded.
Frank,

What are the values of the coil & capacitor of your home made filter, I might be interested.
Thanks.
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Old Dec 14, 2011, 07:43 AM
The Flying Circus
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Adelaide South Australia
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I dont know what the inductor was as it was an off the shelf item that was unmarked. It was a toroid wrapped with a heap of turns of quite heavy enameled wire. Inductor in series with (+). I used a 1000uF 24v electrolytic cap across the supply, and sealed the lot in heatshrink. I will see if I can get a pic of the inductor later. Its past bedtime now and I desperately need my beauty sleep.
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Old Dec 14, 2011, 08:00 AM
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Miami
Joined Apr 2005
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Quote:
Originally Posted by ommadawn View Post
That is a very sore point. I dont usually use a separate battery.............So NO I DONT USE A SEPARATE BATTERY ANYMORE!!!!!!!!!!!!
Cheers
Frank
I always use just ONE battery also Having to monitor and charge 2 seperate batteries is just unneeded extra weight, overly complicated, a pain in the ass, and really increases the risk for the type of crash you had . I set my ESC to cut out the motor long before the battery is dead. I can fly for another hour once the motor cuts out.

One battery will work very well ! If needed, some simple filtering will solve any interference problems form motor / ESC.

Mike
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Old Dec 14, 2011, 08:04 AM
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Quote:
Originally Posted by ommadawn View Post


Its not always true that gliders need to be light. Thermals can be very strong, and a higher wing loading adds stability. Onboard stabilization like RVOSD G5 makes it easier to thermal as well.
Fullsize actually carry ballast to improve L/D at speed.
Cheers and Seasons Greetings,
Frank
I just added 5 ounces of lead ballast to the nose of my glider, so I hope you are right. This one has the wing loading of a Jet If it test flys well, I will take the lead off and lengthen the nose to correct the CG problem. I am starting to find that most gliders need a longer nose balance without putting a bunch of lead in.

Mike
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Old Dec 14, 2011, 08:27 AM
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Las Vegas, NV
Joined Sep 2003
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I fly a two battery system...never had an issue. My 3S 1000mAh Vtx battery easily outlasts my 5000mAh main battery on 30 minute flights. I can usually get two flights on the one VTx battery with no issues. The VTx battery powers my DOSD and VTx. My camera is a GoPro with internal battery. My main pack powers the motor, Rx, and servos.
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Old Dec 14, 2011, 08:59 AM
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Le Havre, FRANCE
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Quote:
Originally Posted by JettPilot View Post
I always use just ONE battery also Having to monitor and charge 2 seperate batteries is just unneeded extra weight, overly complicated, a pain in the ass, and really increases the risk for the type of crash you had . I set my ESC to cut out the motor long before the battery is dead. I can fly for another hour once the motor cuts out.

One battery will work very well ! If needed, some simple filtering will solve any interference problems form motor / ESC.

Mike
Mike, what kind of filtering do you use on your plane, can I copy?
Here's the video I was talking about, not very nice, huh?

VID0010 (10 min 38 sec)
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Old Dec 14, 2011, 09:23 AM
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I moved my attention grabbing message to the next page because I figured he would probably miss it at the end of this page
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Last edited by atopcu; Dec 14, 2011 at 09:48 AM.
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