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Old Oct 04, 2012, 01:53 AM
FPV in Hawaii
iskess's Avatar
United States, HI, Kailua
Joined Feb 2012
2,360 Posts
I'm flying a Twinstar and I've been having some vibration and trim issues. I bought a digital tachometer and found that one motor is putting out 800 rpm more than the other. I'm very pleased to find the problem, but not sure what to do about it.
I can only afford one channel for throttle. Is there a way to balance the PWM signals? A variable resistor perhaps?
I know this is the wrong thread, but I can't find the right one and this feels more like home.
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Old Oct 04, 2012, 02:52 AM
Registered User
Castel101's Avatar
United States, OR, Portland
Joined Sep 2011
766 Posts
Maybe try a JR matchbox?
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Old Oct 04, 2012, 03:08 AM
Team Lumenier Pilot
Grazer's Avatar
Australia, WA, Perth
Joined Aug 2011
2,543 Posts
Quote:
I can't speak for anything FPV, but I can say don't use the DX6i for FPV! I flew LOS and "browed out" many times causing a crash. If you want to stick with 2.4ghz for controlling your plane, go with a Turnigy 9x with FRsky module. Or do what I did and get a cheap 72mhz radio. I have a JR XP6102.
On my SW 1900mm FPV setup, I have been flying 2.4Ghz Spektrum. Tx is DX8 and Rx is a 9020 with two satellites. The satellites have been carefully positioned. One horizontal at nose and one vertical at rear of fuselage. I also used antenna tube to keep the sat antennas straight and at the desired angle. Furthest I pushed out is 3.2kms at a fairly conservative altitude of 150m.
I am impressed with that range. Having said this, I have just invested in a EZ UHF setup (433Mhz) for longer range flights.
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Old Oct 04, 2012, 10:00 AM
Gary
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United States, MD, Salisbury
Joined Mar 2011
2,474 Posts
Grazer: thanks for that input! I'm planning on replacing my AR6000 with the Ar8000 w satellite on my FPV/DX8 bird. I'm not really looking for distance as much as super reliability, so I can port over to my Cinestar. I'm thinking 1.2ghz for the video and switching to Graupner mx-20 for it's built-in diversity and telemetry. The guys at Quadrokopter have been testing the Lawmate 1.2 for 2.4ghz signal problems and have seen none. The nice thing about Mikrokopter is the SD card stores the signal strength data (along with alot of other stuff). With a HK 5.8ghz 200mw I got no discernible change in signal strength vs. unplugged after 5 flights with my DX8. Which is why I asked about why people keep saying "don't use Spekrum". I think at the distances I'm going, less than 1km, I'm good.
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Old Oct 04, 2012, 12:08 PM
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Castel101's Avatar
United States, OR, Portland
Joined Sep 2011
766 Posts
This has been my experience as well. Maybe it's the DX8 that is different but I have reached 10000 feet when my RC control starts to glitch (failsafe RTH engages). This was with an AR8000 with careful satellite placement just as Grazzer.
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Old Oct 04, 2012, 12:43 PM
Rocket Programmer
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United States, AZ, Mesa
Joined Jul 2007
25,460 Posts
Quote:
Originally Posted by Castel101 View Post
This has been my experience as well. Maybe it's the DX8 that is different but I have reached 10000 feet when my RC control starts to glitch (failsafe RTH engages). This was with an AR8000 with careful satellite placement just as Grazzer.
I think it's more likely the receiver than the transmitter. If you're using a DSMX receiver with a satellite, it's a much better system. I had trouble with a standard DSM2 receiver, but the DSM2 receiver with the satellite worked really well. I did a lot of testing to figure out how to place it though, and some placements didn't work. Basically my video transmitter is in the tail, and the receiver is in the fuse, but the satellite is way out on the wing, as far as I could get it. This allowed me to have good control from one runway to the next at our field, but I think that's not much more than half a mile.
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Old Oct 04, 2012, 01:16 PM
KG5AWQ
guaglione87's Avatar
United States, TX, Arlington
Joined Apr 2012
687 Posts
what are good clover leaf antennas to get with the hk 5.8 200mw tx rx?
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Old Oct 04, 2012, 02:22 PM
Gary
glmccready's Avatar
United States, MD, Salisbury
Joined Mar 2011
2,474 Posts
Thanks guys! It is nice to know I'm not the only one using Speckrum. I'm not going out very far, and have had no trouble. Alex just put the scare in me, and I trust him to know. But I guess alot of the problems occur when you push the envelope of distance. I'm only flying quads close to home, no more than 1000ft, and when I go over 700ft I add altitude. Just put my AR8000 with satellite on, for extra safety.
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Old Oct 04, 2012, 02:47 PM
"FPV"er not a "LOS"er
Wettfeat's Avatar
United States, NC, Charlotte
Joined Feb 2012
360 Posts
Quote:
Originally Posted by ror1 View Post
sorry why not?
if go out of range you lose plane?
Yes. But you don't go out of range and learn to notice when your aircraft is ABOUT to go out of range.
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Old Oct 04, 2012, 06:19 PM
Unregistered User
cmanley_nl's Avatar
The Netherlands
Joined Jul 2010
511 Posts
With ESC voltage spikes, are there voltage spikes on the ground too?

It is well known that in all battery to ESC connections, there are voltage spikes.
But are there voltage spikes on the ground wire too?
That's a very critical question in determining how to design a FPV circuit.

Example of why it's so important to know:
In a typical 3S lipo setup, there's a 5V UBEC (with filter) for RX, the OSD taps it's power from the current sensor (filtered or unfiltered), and a single RSSI wire runs from RX to OSD.
Now perhaps you see the problem: If the ground wire of the lipo-ESC connection is noisy, then the RSSI voltage measured by the OSD can never be stable because the ground potentials will differ at any instance in time due to different filtering ( UBEC toroid at RX versus toroid (or nothing) at current sensor for OSD).
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Old Oct 04, 2012, 09:44 PM
God is my pilot
JimTMich's Avatar
United States, MI, Kalamazoo Township
Joined Aug 2006
2,430 Posts
Quote:
Originally Posted by guaglione87 View Post
what are good clover leaf antennas to get with the hk 5.8 200mw tx rx?
Bluebeams should be top notch. IBCrazy makes those.
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Old Oct 04, 2012, 10:41 PM
KG5AWQ
guaglione87's Avatar
United States, TX, Arlington
Joined Apr 2012
687 Posts
Quote:
Originally Posted by JimTMich View Post
Bluebeams should be top notch. IBCrazy makes those.
Jim - thanks for the info. I actually have those book marked and will probably get those.

I went and got the hk 5.8g 200mw tx rx, so I am hoping that the bluebeams give that setup the boost that it will need.

I am going to do a nice range check with the gear on the bixler soon as it arrives, any idea what i should expect?
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Old Oct 05, 2012, 02:23 AM
Wallop!
Martin7182's Avatar
Bussum, Netherlands
Joined Oct 2009
798 Posts
Quote:
Originally Posted by cmanley_nl View Post
It is well known that in all battery to ESC connections, there are voltage spikes.
But are there voltage spikes on the ground wire too?
That's a very critical question in determining how to design a FPV circuit.

Example of why it's so important to know:
In a typical 3S lipo setup, there's a 5V UBEC (with filter) for RX, the OSD taps it's power from the current sensor (filtered or unfiltered), and a single RSSI wire runs from RX to OSD.
Now perhaps you see the problem: If the ground wire of the lipo-ESC connection is noisy, then the RSSI voltage measured by the OSD can never be stable because the ground potentials will differ at any instance in time due to different filtering ( UBEC toroid at RX versus toroid (or nothing) at current sensor for OSD).
IMO it depends on how you look at it. You may choose any point as GND reference which by definition is 0 volts. If you choose your battery's negative side as GND then, not to violate ohms law, you'll get spikes at the other end of the black wire. But if you choose the ESC's negative as GND then you're safe. Remind that most current flows between lipo and ESC and to your motor. The other electronic parts are way less loaded.

Martin
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Old Oct 05, 2012, 12:44 PM
God is my pilot
JimTMich's Avatar
United States, MI, Kalamazoo Township
Joined Aug 2006
2,430 Posts
Quote:
Originally Posted by guaglione87 View Post
Jim - thanks for the info. I actually have those book marked and will probably get those.

I went and got the hk 5.8g 200mw tx rx, so I am hoping that the bluebeams give that setup the boost that it will need.

I am going to do a nice range check with the gear on the bixler soon as it arrives, any idea what i should expect?
Circular Polaization is important for 5.8Ghz and you get that with the bluebeams. If you are going for distance, you should consider a different type of antenna for your ground station. Something more directional with some gain to it.
This would be a good setup if you are looking for longer range with 5.8. But you would have to keep the ground station pointed at the airplane as the receiver has a cone shape area that it is looking through, not omnidirectional like the bluebeams.

http://www.rcgroups.com/forums/showthread.php?t=1743582
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Old Oct 05, 2012, 01:38 PM
VOLTS > AMPS
stgdz's Avatar
United States, MN, Buffalo
Joined Jul 2011
3,867 Posts
I feel like I need to make a ms project timeline to try and understand all this stuff. Rite now I'm just putting a keychain camera on my radian and pro. I want to do fpv with it on my spectrum so I will pick up a 5.8 GHz setup and just stay with a sole setup.

I've got a go pro and tricopter kit sitting on my bench for awhile. Maybe I will finish it this winter.




With my first statement though, I've been looking at the z2 wing and going the full outfit with it. Odd, ruby, possible UHF. I'm likely going to laminate it but placement of components is critical correct. Once those components are placed its pretty much set in stone. In order to figure the placement do you need to do a lot of low power range testing?
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