HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Mar 27, 2012, 12:12 PM
|Taranis|>|All other Tx's|
scott page's Avatar
United States, WA, Richland
Joined May 2009
6,779 Posts
Quote:
Originally Posted by ands View Post
Guys, just wondering how low you run your 2200's?
Trying to get my head around the fact I can stay up for for than 8 mins as i have only ever flown warbirds.

thanks

ands
So many factors --- I finally got the FrSky telemetry transmitter module so I can KNOW what my cell voltage is.
scott page is offline Find More Posts by scott page
Reply With Quote
Sign up now
to remove ads between posts
Old Mar 27, 2012, 01:07 PM
Registered User
United Kingdom, England, Ripon
Joined Dec 2011
309 Posts
Quote:
Originally Posted by ands View Post
Guys, just wondering how low you run your 2200's?
Trying to get my head around the fact I can stay up for for than 8 mins as i have only ever flown warbirds.

thanks

ands
I "TRY" to run my 2650's to about 70% but it doesnt always happen so many different factors on each individual flight. Ive had LVC after 10mins and then Ive had to land after a 40min flight because I needed to rest my thumbs
Simon2504 is offline Find More Posts by Simon2504
Reply With Quote
Old Mar 27, 2012, 01:21 PM
CURIOSITY Has Landed!
Fugitive_Bill's Avatar
Sydney, Australia
Joined Jul 2005
1,178 Posts
And sometimes ya need to neck and eye balls!
Fugitive_Bill is offline Find More Posts by Fugitive_Bill
Reply With Quote
Old Mar 27, 2012, 01:41 PM
Registered User
Eagle202's Avatar
United States, FL, Clearwater
Joined Aug 2011
1,604 Posts
Quote:
Originally Posted by Dkumagai View Post
No one seems to be asking so one would assume so. In case anyone was being shy, a brownout means current to your receiver has dropped below operating range causing a momentary loss of control. This is typically caused by said receiver being powered by an integrated bec where the current demand from the servos exceeds the maximum supplied current.

This condition will cause your receiver to hard reset and it may take a number of seconds to regain control. Spektrum receivers are notorious for browning out and I've seen a few videos demonstrating they're more susceptible to brownouts than orangerx receivers.

I haven't been able to get my sky surfer w/ar6210 to brownout even with vigorous servo movement, probably because I use an esc with a 3amp bec. I have, however, been able to brown out an orangerx powered by a cheap 20 amp esc on a scratch built plane I have.

I saw somewhere that there is a spektrum product that helps to alleviate brownouts. It's essentially a small capacitor that attaches to the receiver.

Today when I was at the park flying I experienced a momentary link loss due to children crowding around me and asking me to do tricks. Thankfully, the SS is stable enough to where you can let go of the controls for a while and it will fly itself for the most part.
You mentioned that the Spektrum receivers have a tendency to brown out. Is that across the board for Spektrum or just specific receivers?

Does this issue happen in the Spektrum clone receivers or for that matter any other manufacturer of receivers?
Eagle202 is online now Find More Posts by Eagle202
Reply With Quote
Old Mar 27, 2012, 01:48 PM
Suspended Account
Joined Feb 2012
123 Posts
Quote:
Originally Posted by ajbaker View Post
1. First, I am not going to tell you that you are wrong. I have too much respect for you to do that. I think a brief explanation might be more helpful.

2. 1-2 seconds on the 4 receivers (all HK) that I have experienced it on. 2 receivers by accident and two on purpose. I can tell you that ~2 seconds feels like 10 mins. My futaba receivers just cut off the motor with no loss of other controls at all.

3.Yes (for the time stated above).

4. Exactly.

5. Well, in a word, No. All that is needed is the requisite ~4.8v for ~2 seconds so the receiver does not reset. In practical application and my own bench testing, a 10V-3300uf electrolytic capacitor will furnish enough current for ~4-5 secs (servo load dependent). However, if the problem is caused by a jammed servo, then, you are totally right - a capacitor will not stop the brownout.
Also, whether the motor is running is immaterial (for this discussion) because the current going to it is coming from the ESC. As you will recall, the current for the signal wire of the servos (and motor level control only) comes from the inbuilt BEC.


I hope all this helps and that it is useful to some of the readers here that want to know a bit more about ESC's/BEC's. I still feel like it might be a bit OT. But, there seems to be some interest in the topic. At this point, I should probably look for a link to a thread that deals specifically with ESC's and their function because the topic applies to almost all electric planes.
Read about what other folks think about brownout eliminators (capacitors) HERE . That one is the cheapo, too.
AJ
Using the formula E/I = R, 4.5 volts devided by say 300 milliamps (receiver and 4 servos at very conservative demand) equals 15 ohms.

The formula for the RC time constant ( the time in which a capacitor dicharges through a resistance) is R times C in Farads. so 15 times 3,300 times 10 to the minus 6 = 49.5 milliseconds or .0495 seconds.

I'm trying to understand how it could hold the system up for 2 or more seconds. The current drain for the receiver alone is only about 9 milliamps so it could conceivably hold the receiver for about one second. What am I missing here?
buracho topspin is offline Find More Posts by buracho topspin
Reply With Quote  (Disabled)
Old Mar 27, 2012, 02:00 PM
Me a long time ago
Flypoppa's Avatar
London N.E. UK
Joined Jan 2007
6,111 Posts
So what I have been saying is that those capacitors are a waste of time. If the brown out or signal lose is more than a fraction of a second... That's it.
If you had some height and flying carefully such as in glide mode, the time the rx get a signal back say 2 seconds, then no harm will be done.
As for reliability of Spektrum RXs.. There have been rumours about the unreliability. I have never experienced any problems and I have quite a few of them.
Saying this I do like the HK Orange ones. Got a few of them as well.
Flypoppa is offline Find More Posts by Flypoppa
RCG Plus Member
Old Mar 27, 2012, 02:15 PM
Suspended Account
Joined Feb 2012
123 Posts
Quote:
Originally Posted by Flypoppa View Post
So what I have been saying is that those capacitors are a waste of time. If the brown out or signal lose is more than a fraction of a second... That's it.
If you had some height and flying carefully such as in glide mode, the time the rx get a signal back say 2 seconds, then no harm will be done.
As for reliability of Spektrum RXs.. There have been rumours about the unreliability. I have never experienced any problems and I have quite a few of them.
Saying this I do like the HK Orange ones. Got a few of them as well.
A brown out due to the BEC output voltage dropping below the receiver cutoff voltage is different than a brown out due to signal loss but the effect is the same. Regardless, in my opinion your first statement is correct, they are no help. Like you said only time and luck are your friends.

I also fly Spektrum and have only had one issue when a 6110 receiver totally failed in mid flight. Lost a plane on that one and HH gave me a new receiver. But never have had another problem with them.
buracho topspin is offline Find More Posts by buracho topspin
Reply With Quote  (Disabled)
Old Mar 27, 2012, 02:19 PM
Better then Sliced Bread!
NorCalMatCat's Avatar
United States, CA, Arcata
Joined Oct 2011
2,650 Posts
Quote:
Originally Posted by Flypoppa View Post
So what I have been saying is that those capacitors are a waste of time. If the brown out or signal lose is more than a fraction of a second... That's it.
If you had some height and flying carefully such as in glide mode, the time the rx get a signal back say 2 seconds, then no harm will be done.
As for reliability of Spektrum RXs.. There have been rumours about the unreliability. I have never experienced any problems and I have quite a few of them.
Saying this I do like the HK Orange ones. Got a few of them as well.
Assuming your control surfaces stay good when it happens, but reality is brownouts are often caused by using the control surfaces, if you are in the middle of doing a fast turn and the draw of servos causes a brownout more then likely your control surfaces are NOT going to be at neutral when it browns it, it's going to be stuck in what it was.
NorCalMatCat is offline Find More Posts by NorCalMatCat
Reply With Quote
Old Mar 27, 2012, 02:41 PM
Registered User
United States, WI, Fond du Lac
Joined Sep 2008
1,740 Posts
Quote:
Originally Posted by Eagle202 View Post
You mentioned that the Spektrum receivers have a tendency to brown out. Is that across the board for Spektrum or just specific receivers?

Does this issue happen in the Spektrum clone receivers or for that matter any other manufacturer of receivers?
All 2.4g receivers are more sensitive to voltage than Mhz systems. Spektrum receivers are more sensitive than the OrangeRX receivers in my experience.

That said, there's nothing wrong with Spektrum. You just need to use quality ESC's or a separate switching BEC. Spektrum receivers will flash if they experienced momentary low voltage. If they come down flashing, you need a better power supply to the receiver.
pmullen503 is offline Find More Posts by pmullen503
Reply With Quote
Old Mar 27, 2012, 04:13 PM
Registered User
United States, WA, Seattle
Joined Oct 2011
286 Posts
Quote:
Originally Posted by ands View Post
Guys, just wondering how low you run your 2200's?
Trying to get my head around the fact I can stay up for for than 8 mins as i have only ever flown warbirds.

thanks

ands
I can run up to 30 min on my 2200s depending on throttle usage with a 450 Watt setup. Granted, I do a fair amount of gliding, so your mileage will vary.
Dkumagai is offline Find More Posts by Dkumagai
Reply With Quote
Old Mar 27, 2012, 04:29 PM
Registered User
Joined Oct 2007
66 Posts
Quote:
Originally Posted by buracho View Post
Using the formula E/I = R, 4.5 volts devided by say 300 milliamps (receiver and 4 servos at very conservative demand) equals 15 ohms.

The formula for the RC time constant ( the time in which a capacitor dicharges through a resistance) is R times C in Farads. so 15 times 3,300 times 10 to the minus 6 = 49.5 milliseconds or .0495 seconds.

I'm trying to understand how it could hold the system up for 2 or more seconds. The current drain for the receiver alone is only about 9 milliamps so it could conceivably hold the receiver for about one second. What am I missing here?
Buracho, your missing nothing. I just measured the current drain from 4 HK Orange 6 ch. rcvrs., and 1 Spektrum 6100e 6 ch. rcvr. and the AVERAGE
current drain for those 5 receivers was 23.5ma. @ 5.01V input from the ESC. Using those figures, it would be absolutely impossible to maintain the terminal voltage of a 3300uf capacitor at 4.8V as stated in the previous post by AJ. In just 1 RC time constant, approx. .7secs., the terminal voltage of the capacitor would be about 1.84V. That's far below the "requisite ~4.8v for ~2 seconds so the receiver does not reset" as claimed by AJ. He also states that in a practical application, and his own bench testing, that a 3300uf capacitor will furnish enough current for 4-5secs. That must be some very special 3300uf cap that he's using.
Ole Joe is offline Find More Posts by Ole Joe
Reply With Quote
Old Mar 27, 2012, 04:55 PM
Registered User
Eagle202's Avatar
United States, FL, Clearwater
Joined Aug 2011
1,604 Posts
Quote:
Originally Posted by Ole Joe View Post
Buracho, your missing nothing. I just measured the current drain from 4 HK Orange 6 ch. rcvrs., and 1 Spektrum 6100e 6 ch. rcvr. and the AVERAGE
current drain for those 5 receivers was 23.5ma. @ 5.01V input from the ESC. Using those figures, it would be absolutely impossible to maintain the terminal voltage of a 3300uf capacitor at 4.8V as stated in the previous post by AJ. In just 1 RC time constant, approx. .7secs., the terminal voltage of the capacitor would be about 1.84V. That's far below the "requisite ~4.8v for ~2 seconds so the receiver does not reset" as claimed by AJ. He also states that in a practical application, and his own bench testing, that a 3300uf capacitor will furnish enough current for 4-5secs. That must be some very special 3300uf cap that he's using.

A brown out is nothing more than a voltage dip. The electronics to maintain or regulate a constant voltage is comprised of more than capacitors.

My guess is that the receiver electronics has some sort of voltage regulation circuit already inside. Using the calculations above does not take that circuitry into the equation.

Adding a capacitor to the circuit provides a place to store voltage. How the capacitor discharges that stored voltage is based on the other circuitry in the receiver. So the voltage levels and discharge duration may not be so easily calculated without knowing the rest of the circuit since it is not just a resistor.

Vince
Eagle202 is online now Find More Posts by Eagle202
Last edited by Eagle202; Mar 27, 2012 at 04:58 PM. Reason: sign off
Reply With Quote
Old Mar 27, 2012, 05:13 PM
ICrashRCs
United States, TN, Memphis
Joined Jun 2011
1,196 Posts
my layman's guess,
The voltage shortage is normally fractional.
The reset time is the big delay.
If the capacitor avoids the voltage shortage,
there is no multi second delay.

For me the question would be, How long does the voltage shortage actually last?
IFlyRCs is offline Find More Posts by IFlyRCs
Reply With Quote
Old Mar 27, 2012, 05:22 PM
Argue for your limitations
ajbaker's Avatar
Lincoln, CA
Joined Oct 2006
8,424 Posts
Quote:
Originally Posted by buracho View Post
Using the formula E/I = R, 4.5 volts devided by say 300 milliamps (receiver and 4 servos at very conservative demand) equals 15 ohms.

The formula for the RC time constant ( the time in which a capacitor dicharges through a resistance) is R times C in Farads. so 15 times 3,300 times 10 to the minus 6 = 49.5 milliseconds or .0495 seconds.

I'm trying to understand how it could hold the system up for 2 or more seconds. The current drain for the receiver alone is only about 9 milliamps so it could conceivably hold the receiver for about one second. What am I missing here?
What you are forgetting is the current already present from the ESC (actually, the BEC portion of the ESC.) That current is anything but constant and therefore not totally predictable. I can tell you from practical testing that using larger caps, I can get 8-12 seconds of "battery time" (for a receiver and one servo) from a charged capacitor .
AJ
ajbaker is offline Find More Posts by ajbaker
Reply With Quote
Old Mar 27, 2012, 05:25 PM
Argue for your limitations
ajbaker's Avatar
Lincoln, CA
Joined Oct 2006
8,424 Posts
An ounce of prevention

Quote:
Originally Posted by Flypoppa View Post
So what I have been saying is that those capacitors are a waste of time. If the brown out or signal lose is more than a fraction of a second... That's it.
If you had some height and flying carefully such as in glide mode, the time the rx get a signal back say 2 seconds, then no harm will be done.
As for reliability of Spektrum RXs.. There have been rumours about the unreliability. I have never experienced any problems and I have quite a few of them.
Saying this I do like the HK Orange ones. Got a few of them as well.
Not exactly. The capacitor prevents a brownout from occurring. It is like having a bigger battery on board to stop any brownout BEFORE it occurs.
AJ
ajbaker is offline Find More Posts by ajbaker
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
For Sale Cyber Sky Parachute (Sky Surfer) shv2sail Aircraft - Electric - Airplanes (FS/W) 6 May 28, 2013 03:14 AM
Discussion Sky Surfer nickwayne11c Electric Plane Talk 15 Nov 18, 2011 03:36 PM
Discussion Banana Hobby Sky Surfer Problems cavy92 Electric Plane Talk 56 Nov 02, 2010 03:49 AM
Question Sky Surfer LiPo mod, help... Freight Dog Power Systems 0 Aug 17, 2006 02:45 PM
Swashplate Assembly with Center Ball; is this the swash with ball mod i want? tekforce Micro Helis 4 Feb 08, 2004 06:28 PM