Brown outs and Grey areas - the truth!

[Bob Cotsford]

Good point Gangster, with the instant reconnect we had on AM and FM systems any signal loss would have been included in the category of 'glitch' regardless of cause. I think you are right that it was the slow reconnect times on early 2.4 systems that highlighted low voltage drop-out as an issue. It'd be interesting to see a comparison on PCM/IPD FM systems against early and current 2.4 systems.

When FrSky 2.4GHz receivers and modules first appeared Rob Carpenter asked me to try one out and I tested the low voltage drop out using a variable supply and various servos. What I found was that the servos stopped working at around 2.9-3.2v depending on brand and load, but the receiver still worked down to 2.8v so a low battery would have killed the plane long before the receiver stopped working!

[Simon Chaddock]

I would tend to agree that 'brown out' as a problem has only appeared on 2.4 simply because 35 Rxs tend to recover from a voltage loss/drop very quickly.

I still fly both and when I connect the battery on a 2.4 plane I am just starting to think "hello what's wrong" before the ESC arms. The only 35 Rx that seems to take anything like as long are the 'synth' type with no crystal.

[gangster]

2.9-3.2v depending on brand and load, but the receiver still wor ked

Yes that is exactly what I discovered with the Spektrum 6210 this morning. So to make the blanket statement that Spektrum receivers suffer brownout badly is incorrect Probably referred to some of the earlier ones. I have no "Pre DSMX" receivers to try

Will try on an Orange one later to see what that does. I would be interested what the recovery time is for earlier receivers, certainly was not an issue on the 6210

Oh no! another test to do Simon Synth 35 vs crystal

[Don Fry]

Correctly installed, with a tidy battery, maintained, radio sets in the 1960's were reliable. Correctly installed, with a tidy battery, maintained, today, radio sets are incredibly reliable. I, in 50 years in this game have yet to see an aircraft go in due to failure of the system {except the switch, it seems to be the same rubbish as 50 years ago}. Pilot failure, yes, airframe failure, yes, boredom, yes, poor installations, yes, blame something else, yes. In fairness a couple of rubbish builds by the manufacture, usually a dry joint. Radio design, in fairness be it JR., Sanwa, Futaba, spektrum, Fleet, OS, Horizon ad sickness ( can't spell nausium) has worked, waggle the stick, and it does what you put in, not necessarily what you wanted.

[Dave Hopkin]

Posted by Donald Fry on 04/04/2015 17:09:43:

Correctly installed, with a tidy battery, maintained, radio sets in the 1960's were reliable. Correctly installed, with a tidy battery, maintained, today, radio sets are incredibly reliable. I, in 50 years in this game have yet to see an aircraft go in due to failure of the system {except the switch, it seems to be the same rubbish as 50 years ago}. Pilot failure, yes, airframe failure, yes, boredom, yes, poor installations, yes, blame something else, yes. In fairness a couple of rubbish builds by the manufacture, usually a dry joint. Radio design, in fairness be it JR., Sanwa, Futaba, spektrum, Fleet, OS, Horizon ad sickness ( can't spell nausium) has worked, waggle the stick, and it does what you put in, not necessarily what you wanted.

[gangster]

I agree with every word of that Donald

[Don Fry]

Clever me, 2 bottles and 4 courses for lunch. Gale blowing.

[Tim Mackey]

Posted by Simon Chaddock on 04/04/2015 12:34:48:

I would tend to agree that 'brown out' as a problem has only appeared on 2.4 simply because 35 Rxs tend to recover from a voltage loss/drop very quickly.

I still fly both and when I connect the battery on a 2.4 plane I am just starting to think "hello what's wrong" before the ESC arms. The only 35 Rx that seems to take anything like as long are the 'synth' type with no crystal.

Ah but Simon with respect the delay after switching on is not connected with brown outs - this delay is merely whilst the tx acquires its channel and talks to its matched rx. Once they have done this "handshake" communication is instant. If signal is lost there could well be delay whilst they reconnect but again this is NOT brown out

Brown out is solely a failure due to insufficient power supply level and is not connected with rf signal loss.

As to reconnect time after BROWN OUT Spektrum's patented "quick connect" adressed this very well. In all tests that I did, reconnection was instantaneous and indeed were it not for a flashing led on the rx one would not even know that a brown out had occured.

[Paul Marsh]

The difference between 2.4 rx and 35 meg is that 2.4 uses a processor, 35 meg don't. And when the voltage drops, the processor crashes and has to re-boot - like your PC. Get low battery and it shuts down. 35 MGhz rx's are analog and will work to almost no voltage - usually the servos stop working before.

[Bob Cotsford]

Paul, PCM, IPD, synthesised frequency and 2.4GHz receivers all use signal processing programming. I would think that the main difference is that 2.4 needs to initialise it's frequency hopping algorithm, then locate and get in sync with it's matching transmitter. I'd still be interested in how a modern but more complex 2.4GHz processor compares with older tech but simpler FM processing.

[ted hughes]

This is not being antagonistic, but it will probably be seen as such.

I have heard many anecdotes about signal loss due to:trees,wires,pylons,solder joints, manufacturers, brown outs, blackouts,etc.

These are traced back as the causes as a sad owner recovers the various components of his pride and joy.

Occam's razor! The simplest explanation is likely to be the true one! We lost flying control!

During a slack period at work I have been YouTubing various full scale accidents, in which the pilots, against all odds, and with their lives at stake, have lost control of their aircraft. Looping too low to the ground (a common one),banking too steeply, allowing speed to decay on approach - all of these things have killed pilots and have been recorded.

Inexperienced r/c pilots seem to have a lot of mechanical and electrical faults. Experienced r/c pilots have less. Just saying.

 

 

Edited By ted hughes on 05/04/2015 02:57:59

Edited By ted hughes on 05/04/2015 02:58:43

[Masher]

Now I agree with you Ted!

[trebor]

I had my first dead plane, lost control while on a buddy link. Not too much damage but it turned out to be on a dry joint on a pre soldered brand new battery. Also as I fitted the motor had connectors fall off the wires. As this is my first lipo powered plane I've found you can't trust anything.

[Robert Armstrong 2]

Just a thought;

The advent of 2.4Ghz radios has coincided with a trend to significantly bigger models at club level, Bigger models need bigger servos which place more load on the poor batteries, which probably haven't quite kept up with the demands placed upon them in manny cases. Has 'club level' power supply provision kept up with the requirements of current 'club level' models?