HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Mar 06, 2011, 11:57 PM
Registered User
Kambalunga's Avatar
Deutschland, Hessen, LA
Joined Jan 2009
1,203 Posts
Quote:
Originally Posted by cayars View Post
Yea, but this is about Spectrum equipment and not Futaba FAST.
Yea, the power recommendation and the brownout threshold are two different things. That is what you not understand.

A system with a lower latency has a higher power demand.
The latency of a DX7 and DX6i is higher as for a DX8 or DX7se.
A power source that only just works with a DX7 or DX6i may be caused a brownout with a DX8.
Kambalunga is online now Find More Posts by Kambalunga
Reply With Quote
Sign up now
to remove ads between posts
Old Mar 07, 2011, 12:14 AM
Registered User
cayars's Avatar
Bridgeton, NJ
Joined Mar 2009
2,083 Posts
Kambaluanga, that makes no sense.

The DSM2 receiver should not know or care what transmitter is feeding it info and thus the power requirements should not change.

But what I was commenting on was that you were quoting FAST info and it's different for DSM.
cayars is offline Find More Posts by cayars
Reply With Quote
Old Mar 07, 2011, 12:34 AM
Registered User
Kambalunga's Avatar
Deutschland, Hessen, LA
Joined Jan 2009
1,203 Posts
Wrong assumption again!
DX7se, DX7 and DX6i all clean DSM2 but different latency.
Then is not the RX your problem, with a lower latency increased your servo power demand.

http://rc.runryder.com/helicopter/rr...?p=1310272&i=2
Kambalunga is online now Find More Posts by Kambalunga
Reply With Quote
Old Mar 07, 2011, 01:19 AM
EDF Junkie
Pacific Northwest
Joined Oct 2007
1,496 Posts
Quote:
Originally Posted by Kambalunga View Post
Wrong assumption again!
DX7se, DX7 and DX6i all clean DSM2 but different latency.
Then is not the RX your problem, with a lower latency increased your servo power demand.

http://rc.runryder.com/helicopter/rr...?p=1310272&i=2
Please help my pea brain understand this. You are saying the DX8 updates the servo positions more frequently than the DX7 does so the servos use more power? Therefore if your plane has marginal power you may brownout your receiver on the DX8 when you didn't before with the DX7 or DX6i?

Then if voltage doesn't return to an acceptable level you crash because the receiver isn't functional. Or if acceptable power is restored but your receiver doesn't do a quick reconnect after the brownout you crash.

Is this the possible scenario?
NwRcFlight is offline Find More Posts by NwRcFlight
Reply With Quote
Old Mar 07, 2011, 01:52 AM
Registered User
Central California
Joined Dec 2006
2,513 Posts
Quote:
Originally Posted by cayars View Post
Thanks Andy, guess I'll cross that off my list.

Anything you can think of off the top of your head I didn't cover I should try/test?
Thats kind of a loaded question.The one most important thing is to assure the system is getting the proper voltage through the entire flight under all conditions of load.How a person goes about doing this is a whole other topic.
The information is there if you search a little I know its been gone over.

Quote:
Originally Posted by cayars View Post
Kambaluanga, that makes no sense.

The DSM2 receiver should not know or care what transmitter is feeding it info and thus the power requirements should not change.

But what I was commenting on was that you were quoting FAST info and it's different for DSM.
Quote:
Originally Posted by Kambalunga View Post
Wrong assumption again!
DX7se, DX7 and DX6i all clean DSM2 but different latency.
Then is not the RX your problem, with a lower latency increased your servo power demand.

http://rc.runryder.com/helicopter/rr...?p=1310272&i=2
Carlo
I know at first glance it doesn't seem to make sense but think about it a bit more.
Ive heard many different explanations as to why this occurs.But what he is saying is exactly what I have noticed happens to be true.In my case the differences between my DX7 and DX8 werent alot different.But it was enough to see that DX8 does use power differently and in general just a little bit more of it.I almost got sucked into going farther to try to figure out why.Too much like school then.I just want to fly and have fun not argue about why something is the way it is.Apply a little basic logic...Get some basic test equipment setup your plane making sure it has enough voltage at the Rx and go fly it.This is true for any combination of equipment not just the DX8.
I still say that all other things equal the DX8 is a bit more demanding to the Rx/servo power.A model that may have been running marginally with no obvious issue like it stops working and crashes could very possibly be pushed over the edge being used with a different Tx.Thats my story and Im sticking to it.
aerocal is offline Find More Posts by aerocal
Reply With Quote
Old Mar 07, 2011, 01:59 AM
Registered User
Central California
Joined Dec 2006
2,513 Posts
Quote:
Originally Posted by NwRcFlight View Post
Please help my pea brain understand this. You are saying the DX8 updates the servo positions more frequently than the DX7 does so the servos use more power? Therefore if your plane has marginal power you may brownout your receiver on the DX8 when you didn't before with the DX7 or DX6i?

Then if voltage doesn't return to an acceptable level you crash because the receiver isn't functional. Or if acceptable power is restored but your receiver doesn't do a quick reconnect after the brownout you crash.

Is this the possible scenario?
Bingo.
It also cant quick connect if the power takes time to return.Like the time it takes an overworked hot BEC to cool down and return its output.
aerocal is offline Find More Posts by aerocal
Reply With Quote
Old Mar 07, 2011, 02:00 AM
Registered User
Kambalunga's Avatar
Deutschland, Hessen, LA
Joined Jan 2009
1,203 Posts
Quote:
Originally Posted by NwRcFlight View Post
Please help my pea brain understand this. You are saying the DX8 updates the servo positions more frequently than the DX7 does so the servos use more power? Therefore if your plane has marginal power you may brownout your receiver on the DX8 when you didn't before with the DX7 or DX6i?

Then if voltage doesn't return to an acceptable level you crash because the receiver isn't functional. Or if acceptable power is restored but your receiver doesn't do a quick reconnect after the brownout you crash.

Is this the possible scenario?

The RX must not stop working your servos can make all the trouble. The most servos need a 3V servo impulse voltage. The problem is some servos twitch at such low voltage that make this even worser. The twich after the voltage rise and then drops the voltage again, plus now maybe the increased airspeed caused a increased power demand. The twitch is the most time in the same servo travel direction. Simpel an infinite loop.
Kambalunga is online now Find More Posts by Kambalunga
Last edited by Kambalunga; Mar 07, 2011 at 02:24 AM.
Reply With Quote
Old Mar 07, 2011, 02:19 AM
Registered User
Kambalunga's Avatar
Deutschland, Hessen, LA
Joined Jan 2009
1,203 Posts
Quote:
Originally Posted by aerocal View Post
Bingo.
It also cant quick connect if the power takes time to return.Like the time it takes an overworked hot BEC to cool down and return its output.
Therefore are ESC with linear a BEC the worst choice. The a linear regulator have a thermal fuse to avoid thermal damage. More input voltage caused a higher dissipation power and a lower possible servo count. Part load make this even more worser, the ESC produce additional heat. Then maybe the side where the BEC placed has no cooling--> thermal shutdown.
Kambalunga is online now Find More Posts by Kambalunga
Reply With Quote
Old Mar 07, 2011, 02:22 AM
EDF Junkie
Pacific Northwest
Joined Oct 2007
1,496 Posts
Quote:
Originally Posted by Kambalunga View Post
The RX must not stop working your servos can make the trouble. The most servos need a 3V servo impulse voltage. The problem is some servos twitch at such low voltage that make this even worser. The twich after the voltage rise and then drops the voltage again, plus now maybe the increased airspeed caused a increased power demand. The twitch is the most time in the same servo travel direction. Simpel an infinite loop.
So another possible scenario is: you have a model you've been flying with a DX6i or DX7 and it has marginal power but has been working fine. You switch over to the DX8 and because of the lower latency it updates the servos more often requiring more power. Because of the increased servo power requirements when using the DX8 your voltage drops below 3v but is above 2.7v. The receiver is still functioning because you're above 2.7v but the servos are not functioning. They are twitching and trying to achieve the set position. You have no control and crash.

One of the firmware updates set the default frame rate from 11ms to 22ms. Was this done to help alleviate this issue perhaps? So the servos don't update position as frequently and therefore don't use as much power. When using analog servos the frame rate is 22ms (same as the DX7) and only digital servos use the 11ms rate.

The bottom line seems to be that you can have a failure with a plane that is working fine with a DX6i/DX7 simply because you change to a DX8 in combination with having a marginal power system. It explains what might have happened in Cayers case.
NwRcFlight is offline Find More Posts by NwRcFlight
Last edited by NwRcFlight; Mar 07, 2011 at 02:31 AM.
Reply With Quote
Old Mar 07, 2011, 03:39 AM
Registered User
Vienna, Austria
Joined Oct 2010
2,599 Posts
Sorry guys, but the DX8 does not cause more power draw in the model. At least in my model. If you use the same RX (6200) on DX6i and DX8, the DX8 cannot feed 11ms to the model, simply because the RX is not capable. Also, if a brownout occurs, the telemetry alarm goes off and the orange led blinks. Also, my setup on my 450 has plenty of power (BEC has 10A peak, that should be sufficient for 4 small servos). No brownout. I think of a bug in the RF deck, when transmitting in 6ch legacy mode, the is some data which makes the RX go nuts. Just an idea....
Mukenukem is offline Find More Posts by Mukenukem
Reply With Quote
Old Mar 07, 2011, 04:22 AM
Registered User
Kambalunga's Avatar
Deutschland, Hessen, LA
Joined Jan 2009
1,203 Posts
Latency has only secondary to do with framerate.
When I use the DX6i with the AR6100 is the servo travel slower as with the DX8.

10A peak how long?
The tailservo a digital over gyro?
120 swashplate mean that 3 servos can simultan run on.
What typ of servos?
Measure first your voltage and the current.

ESC Kontronik?
Kambalunga is online now Find More Posts by Kambalunga
Last edited by Kambalunga; Mar 07, 2011 at 04:35 AM.
Reply With Quote
Old Mar 07, 2011, 04:31 AM
Suspended Account
Rhode Island USA
Joined Aug 2010
5,350 Posts
Quote:
Originally Posted by aerocal View Post
Pete Pete Pete shame shame shame.



Ths really serves no useful purpose.Honestly it is kind of annoying as well.
Wondering if every flight is your last and losing planes is kind of annoying!
VP
Victory Pete is offline Find More Posts by Victory Pete
Reply With Quote  (Disabled)
Old Mar 07, 2011, 05:26 AM
Registered User
egicar's Avatar
Nuvolera (Italy)
Joined Jul 2007
666 Posts
About brownout.

I think that the larger part of brownout problems is related with an insufficient power supply (BEC underdimensioned or something else).
Why I think so?
Kambalounga has already written many interesting thing on this problem, but I want to add:
- we can find on the market some HV servos, that drops a lot of current when under load;
- the DX8 and the DX7SE have 11ms and 2048 steps. That means about the double of servo activity, in confront of what happen with a DX6i or a DX7;
- if you add an electronic flybarless system, the current consumption will increase even more, because the system will give work to the servos more frequently than the direct (human) command from the transmitter.
Maybe in the next future, the ESC Manifacturers will implement some better and powerful BEC in their ESC.
In my experience, a 200 class heli with 4 powerful servos and an electronic flybar system can drop more than 2A (peak) in some circumstances and the majority of ESCs for this class of heli has an integrated 2A linear BEC.
If you go with many S LiPo (4S or more), the charge on the (linear) BEC is increased.
In conclusion of my thinking, we should double check our power supply capacity of delivery current without entering in thermal protection.
IMO, I would exclude a loss of signal due to a TX/RX issue, in the 99% of brownout cases, pointing the attention on the power supply.

Ciao,
Egidio
egicar is offline Find More Posts by egicar
Reply With Quote
Old Mar 07, 2011, 07:19 AM
Registered User
United States, AZ, Gilbert
Joined May 2005
148 Posts
So I saw back on pg 133 that onthesnaps radio was going into bind mode when the AUX3 knob was turned all the way to the left. I found today that mine is doing the same thing and I wanted to see how many people have experienced this. To test yours; turn the AUX 3 knob all the way to the left (counterclockwise) and then turn on the radio. Should do nothing but mine goes into bind mode. I have tried this on both firmwares available.
carrera0to60 is online now Find More Posts by carrera0to60
Reply With Quote
Old Mar 07, 2011, 07:59 AM
Registered User
Orlando, Fl
Joined Jan 2008
1,494 Posts
Quote:
Originally Posted by aerocal View Post
Man it really as been a long winter.You guys are like a pack of hungry jackals. Oh yeah...Im going flying and having some fun so neener neeener neener.Im issueing a recall on warmer nicer flying weather.
I had to look that one up.
http://wiki.answers.com/Q/What_is_a_%27neener%27
I guess it is a sign that I'm getting old.
jhroof is offline Find More Posts by jhroof
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Question Receivers that work with Spektrum Radios that are not made by Spektrum BD Flyer Radios 29 Sep 26, 2010 04:09 AM
Discussion Spektrum AR6100E or Spektrum AR6100? LaurenceGough Off-road Cars 23 Aug 06, 2009 05:33 AM
For Sale Parkzone 5ch DX10 w/Receiver ch54 CarlHill Aircraft - General - Radio Equipment (FS/W) 7 Jul 10, 2009 12:07 PM
Discussion Can I use a Spektrum Air RX with a Spektrum Surface TX? Bigmaxy Radios 1 Jan 19, 2008 07:57 PM
Sold GeForce 8400Gs PCIx DX10 video card GFBurke Non R/C Items (FS/W) 6 Sep 05, 2007 10:43 PM