[Phil_G]

They are in a portion of the electromagnetic spectrum that simply does impact on the 2.4GHz equipment

As our colonial friends would say, "NOT!"

[grahamstanley]

yep shows are ditching 35 just so they don't have to pay people to run the TX tent
so i'm forced to borrow the gear from the club trainer which will be plopped into place ( i might not even bother removing the 35mhz rx ) and the tranny quickly programmed up
i may or may not do this the weekend before the show so i can get a test flight in, might even be on the friday when we get there.

result is i'll be using a tranny i'm not used to, with control deflections i'm not used to and the first time i get to find out how that feels is when i'm flying infront of 10k people, with 10 other planes, at 120mph flying around trees.

the change of being shot down at a show now is very slim, i've never had an issue, the system worked just fine. ( however that might change for the reason i'll state in a min ) no-one at shows is selling 35mhz, and no-one is now using it in their show plane, so no-ones quickly checking something back at the campsite.

if anything your now more at risk from someone who thinks it'd be cool to video the show from the air.
where as someone switching on 35mhz is only going to cause a problem to one pilot, assuming they both just happen to be on the same frequency and that the aerial down in the campsite overpowers the aerial up on the flightline ( i've had this happen with just 50' separation, i didn't even notice a glitch! ), a powerful 2.4 transmitter is everyones problem.

of course now 35mhz isn't supported, those still bringing other toys to play with will have the 2.4 mindset, just turn on, no-one else is using it.

I have been shot down at a show on 35MHz.  Someone had probably purchased a radio set and decided to try in in the car park.  I nearly nailed the chap due in the next slot, and he nearly nailed me as he thought I had crashed deliberately    Fortunately Boddo was on Tx control and saved me from a revised nose by showing the pilot the scanner lights...

If the pilot is not familiar with the radio and aircraft set up, he should not fly at a show.  That is not the time or place to try a new radio set up.

I do not think Tx control cost is the issue to organisers, it's the inability to control the public.  2.4 is obviously a huge step forward with it's massive improvement in interference proofing and with the added advantage of telemetry for battery voltage and signal strength at the Rx I will not be going back to 35MHz quickly.

Powerful 2.4 Tx should never be at a show.  Outside broadcast units and other legal users should be well briefed by the organisers.

Having said that, it clearly does not solve all the quality and design issues just by being 2.4.....  Choose the brand with care.     

[Cactus]

I do not think Tx control cost is the issue to organisers

you'd be surprised 

I have been shot down at a show on 35MHz.  Someone had probably purchased a radio set and decided to try in in the car park.

thats pretty bad luck, as i said earlier i had a glitch free flight while someone accidentally turned on 50' behind me and couldn't figure why their plane was going mad, yes they had aerial down but as i was closer to my plane with aerial up i had full control.

[VinceHaworth]

so chaps - if we had a 'dual channel 35mhz system with some fancy interference rejection coding' available, how many of us would buy it in preference to 2.4 ghz kit?
I think FrSky would be our best hope of any manufacturer to produce a 'super' 35mhz tx module & rx.

weatronic have a dual 35mhz system but the prices are expensive, €500 and the rx is a brick

[Lplus]

so chaps - if we had a 'dual channel 35mhz system with some fancy interference rejection coding' available, how many of us would buy it in preference to 2.4 ghz kit?
I think FrSky would be our best hope of any manufacturer to produce a 'super' 35mhz tx module & rx.

weatronic have a dual 35mhz system but the prices are expensive, €500 and the rx is a brick

Much as I'd like to think FrSky could produce such an item, it would have to be something that could be used in multiple countries for the sales to be worth the development.  2.4 is virtually worldwide but I'm not sure how they would produce a system that could be used on 35, 36, 72 Mhz etc.
 

[Yoyo]

Much as I'd like to think FrSky could produce such an item, it would have to be something that could be used in multiple countries for the sales to be worth the development.  2.4 is virtually worldwide but I'm not sure how they would produce a system that could be used on 35, 36, 72 Mhz etc.
 

That was going to be my question - how widespread is 35Mhz?

Although I was also thinking that the RF stage on most 35 txs takes PPM and the receiver decodes it, so if we inject the digi signal to the RF stage and extract the same from inside the rx (as the quadcopter boys do) then that should work for any frequency and also shouldn't invalidate the CE Mark (maybe?).

That would mean using standard kit (well-tested, small, approved  synthesised tx and rx) plus a small PPM->digi hack module inserted between the mixer out and RF in inside the Tx, and a small digi->servo outputs box as well as the rx on board.

That sounds more achievable, but would be a definite knowledgeable enthusiast job to fit, at least until a few known good combinations of tx and rx were well documented...

[mart49]

Quite clearly 2.4ghz is in manufacturers interests. Widely available and cheap ic's and one frequency worldwide albeit with some bandwidth restrictions and output power restrictions which are presumably dealt with in firmware enable the cost of manufacture to be reduced. Result either cheaper sets or greater profits or both. Interestingly however, was looking around PC World with a view to replacing our wireless router to find that 'dual band' routers are available using both 2.4 and 5.3ghz frequencies 'to avoid interference on 2.4ghz'  Whatever next, anyone got any 5.3.ghz chips?

Mart

[aesmith]

Well my RF is a bit rusty, but here goes:

Cheers.  To be honest that sounds too slow.   Obviously any 35MHz system would need to co-exist with conventional 35MHz users, so I don't see how it could use more than one channel without being an absolute minefield for frequency control and transmitter programming.   

Any "smart 35Mhz" system really needs to allow multiple transmitters and models to share a given frequency range.   I had a sort of idea that if the data rate was maybe 50 or 100 times that needed by one model, then the multiple models could share the same frequency while picking up only "their own" data packets a bit like shared media Ethernet.

[VinceHaworth]

Much as I'd like to think FrSky could produce such an item, it would have to be something that could be used in multiple countries for the sales to be worth the development.  2.4 is virtually worldwide but I'm not sure how they would produce a system that could be used on 35, 36, 72 Mhz etc.
 

but there are already synth rx's from corona on 35mhz and 72mhz at £10 a go. The 'super 35mhz' rx could use that off the shelf corona as a starting point ? 
it cannot be that difficult or expensive !

[leccyflyer]

Fantastic service from RS Components. After getting the "voltage regulator" electrolytic capacitors from Ali's last week I found the same gadgets at RS Components and order them on Saturday. They've just been delivered now. That's free postage, Saturday dispatch by Parcelforce  and delivery on the next working day, over a Bank Holiday weekend. Can't praise them enough.

Now then....a question for you electronics gurus - I guess these things are polarised? They have one long leg and one shorter leg - which one is which?

Okay chaps - my boy has informed me that the shorter leg is the negative (and Wiki confirm this) and warned of the dire consequences of incorrect polarity, including the horrible fishy smell The case also  has a silver bar on the side of the capacitor next to the shorter leg, with a big negative symbol on it.

[PDR]

They are normally marked with a stripe on the side of the "can" which indicates the negative leg.

PDR

[leccyflyer]

Cheers - until I'd read the Wiki I hadn't actually realised that those were negative symbols

I've got 15 of the blighters to install now anyway, so I'd better break out the soldering iron and heatshrink.

[Phil_G]

   intrigued....


Phil

[leccyflyer]

I'll recap (no pun intended).

We lost my boy's Ripmax Spitfire last weekend. Total radio failure, but it didn;t go into failsafe as the throttle remained open. After much discussion the consensus was that "it was one of them AR500 things" and that the radio had suffered a brown out and locked out. The voltage on the crumpled pack was fine - 3.85v a cell and well balanced, but I suppose that it is a possibility that throttling up to pull up into a loop at the end of a 7 minute flight might have caused a temporary voltage depression and a brown out. It seems the best explanation. The model performed a series of loops, impacting the ground heavily, totalling the wing and badly damaging the fuselage. Checking the radio - some days later - the RX works, the servos work, the mechanics are all sound. I witnessed that the transmitter did nothing at the time of the crash and that the transmitter voltage was 10.5V, absolutely fine. All the other models on the transmitter performed faultlessly, as had that one.

On mentioning this on another forum, a net-flying colleague mentioned that he always fits one of the Alszone voltage regulators to his models and I bought a few last week and fitted them. they are just a 4700uf 10v electrolytic capacitor with a servo lead and plug, so I sourced the same capacitors from RS Components ('99p each versus £4 each for the model shop version and about £5 for the Spektrum item, apparently).

[JohnB]

On mentioning this on another forum, a net-flying colleague mentioned that he always fits one of the Alszone voltage regulators to his models and I bought a few last week and fitted them. they are just a 4700uf 10v electrolytic capacitor with a servo lead and plug, so I sourced the same capacitors from RS Components ('99p each versus £4 each for the model shop version and about £5 for the Spektrum item, apparently).

What you have described there isn't a voltage regulator, it's a capacitor - a small battery that 'may' just stop some of the voltage drops when demand is high but if your voltage is dropping so much you should look back upstream at batteries and wiring. Fit 5 cell for sure and make sure decent wiring and switch harness is in use.

J

[Phil_G]

IMHO its a placebo Brian... I'm all for decoupling and you'll see all my stuff is liberally sprinkled with mylars and tants. But a cap wont fix the situation you described.
I've posted this a couple of times, but to reiterate:
The idea of a capacitor as some sort of reservoir to supply servos during transient current demands is just unfeasible.
Take the example of a 4700uF capacitor. How much energy will that store?
F = C/V, and V = 5 Volts, F = 0.0047 Farads, thus C = 0.0235 Coulombs = 0.0235 Amp*seconds = 0.00653 mAh

A 4700uF capacitor has a A/H capacity of point nough nought six of a milliamp-hour.

A perfect 4700uF capacitor would supply 3A for just 7.8 milliseconds. Thats discharging it down to zero volts, not the 3.5v (?) minimum we need, which from BEC voltage would be reached in 2 or 3 ms. Once discharged, it contributes nothing, in fact actually absorbs more current if the voltage recovers, which will very slightly extend the time the supply takes to get back to working voltage.

Extra decoupling is usually good thing & wont do any harm, but its not a magic bullet, and it won't 'take over from the BEC' if the voltage sags.
This is just my personal take, but based on a bit of savvy.

Cheers
Phil

[leccyflyer]

What you have described there isn't a voltage regulator,

Yes, I know - that is, however what it says on the label of the packet

it's a capacitor - a small battery that 'may' just stop some of the voltage drops when demand is high but if your voltage is dropping so much you should look back upstream at batteries and wiring.

I'm not at all sure that was the actual cause, but if this helps to smooth out the voltage for a particularly fussy receiver then it's added peace of mind for very little effort.

Fit 5 cell for sure and make sure decent wiring and switch harness is in use.

J

I wouldn't fit a 5 cell nicd/nimh to an electric powered funfighter sized model, with 3 servos on 3s1p lipos. The BEC on a decent ESC, such as the Jeti Advance Plus 40 that was fitted ought to be fine. I might be persuaded to fit a separate switch mode BEC (and indeed have done so) but a 5 cell nimh is not an optimal solution for that type of model IMO.

[leccyflyer]

IMHO its a placebo Brian... I'm all for decoupling and you'll see all my stuff is liberally sprinkled with mylars and tants. But a cap wont fix the situation you described.
I've posted this a couple of times, but to reiterate:
The idea of a capacitor as some sort of reservoir to supply servos during transient current demands is just unfeasible.
Take the example of a 4700uF capacitor. How much energy will that store?
F = C/V, and V = 5 Volts, F = 0.0047 Farads, thus C = 0.0235 Coulombs = 0.0235 Amp*seconds = 0.00653 mAh

A 4700uF capacitor has a A/H capacity of point nough nought six of a milliamp-hour.

A perfect 4700uF capacitor would supply 3A for just 7.8 milliseconds. Thats discharging it down to zero volts, not the 3.5v (?) minimum we need, which from BEC voltage would be reached in 2 or 3 ms. Once discharged, it contributes nothing, in fact actually absorbs more current if the voltage recovers, which will very slightly extend the time the supply takes to get back to working voltage.

Extra decoupling is usually good thing & wont do any harm, but its not a magic bullet, and it won't 'take over from the BEC' if the voltage sags.
This is just my personal take, but based on a bit of savvy.

Cheers
Phil

Thanks for the explanation Phil - I didn't describe it as a placebo, but I do get your point - I described it as a "tiger repellent". I'd never know whether it actually ever did anything, but if fitting separate 3amp switching BECs and one of these to models stops a recurrence of last weeks mishap I'll be happy. 

[Thoughtful_Flyer]

IMHO its a placebo Brian... I'm all for decoupling and you'll see all my stuff is liberally sprinkled with mylars and tants. But a cap wont fix the situation you described.
I've posted this a couple of times, but to reiterate:
The idea of a capacitor as some sort of reservoir to supply servos during transient current demands is just unfeasible.
Take the example of a 4700uF capacitor. How much energy will that store?
F = C/V, and V = 5 Volts, F = 0.0047 Farads, thus C = 0.0235 Coulombs = 0.0235 Amp*seconds = 0.00653 mAh

A 4700uF capacitor has a A/H capacity of point nough nought six of a milliamp-hour.

A perfect 4700uF capacitor would supply 3A for just 7.8 milliseconds. Thats discharging it down to zero volts, not the 3.5v (?) minimum we need, which from BEC voltage would be reached in 2 or 3 ms. Once discharged, it contributes nothing, in fact actually absorbs more current if the voltage recovers, which will very slightly extend the time the supply takes to get back to working voltage.

Extra decoupling is usually good thing & wont do any harm, but its not a magic bullet, and it won't 'take over from the BEC' if the voltage sags.
This is just my personal take, but based on a bit of savvy.

Cheers
Phil

Phil

You are far more knowledgeable than me regarding electronics but aren't you missing a fundamental point here?

You calculation would be valid if the battery were suddenly taken away.

However, we are not talking about that situation are we?

is it not that we trying to keep a voltage on the receiver electronics that is just above the magic (tragic!) brown out point. So, we are only asking the capacitor to contribute a tiny bit?

Chris

[Yoyo]

Phil

You are far more knowledgeable than me regarding electronics but aren't you missing a fundamental point here?

You calculation would be valid if the battery were suddenly taken away.

However, we are not talking about that situation are we?

is it not that we trying to keep a voltage on the receiver electronics that is just above the magic (tragic!) brown out point. So, we are only asking the capacitor to contribute a tiny bit?

That's what 'smoothing' means. It fills in the holes. But not for long...

Do you have any of the little LED battery monitors? They react very quickly to voltage drops - you can see the two or three LEDs below the current level flicker when I waggle the sticks on my planes. Try that with the cap in place and see if it does anything noticeable.

 

[leccyflyer]

What a great idea - I'll give it a go next time I'm at the field and let you know if any tigers appear

[PDR]

You calculation would be valid if the battery were suddenly taken away.

However, we are not talking about that situation are we?

is it not that we trying to keep a voltage on the receiver electronics that is just above the magic (tragic!) brown out point. So, we are only asking the capacitor to contribute a tiny bit?

It's actually the reverse of that.

The trouble is that the amount of energy a capacitor can deliver is proportional to the voltage difference it sees. So it's actually going to have a LOWER "capacity" for a quarter-volt drop than for a full battery-withdrawal event. So where Phil says

"A 4700uF capacitor has a A/H capacity of point nough nought six of a milliamp-hour."

That applies to a full discharge from 5v to zero volts. If you're only looking at the discharge to 3.5v (the point beyond which the Rx will shutdown anyway) then its capacity is:

0.006 * (5 - 3.5) / 5 = 1.8mAh

And it will supply 3A for only a couple of milliseconds (as Phil said). And when it comes to "filling in" short-term drop-outs (negative spikes) even this performance will only be available if there is no significant inductance in the system. Put the capacitors on the end of a piece of cable and the cable inductance will prevent the capacitor pushing current into the system fast enough to do the job. To do any useful decoupling against rapid spikes the connection lengths must be as short as possible - most decoupling capacitors need to be within a millimetre or two of the item being decoupled to keep the inductance low enough to let them do the job.

Capacitors != supply regulation...

PDR

[Harry formerly mpx]

Leccy, what you describe does not match a voltage brown-out on the rx, so several things follow from that:
1.You need to find the real cause, because if it wasn’t a classic brown-out then a brown-out preventer device has not fixed it.

2.Capacitors are not brown-out preventers anyway as has been ably described by Phil

3.Capacitors are fitted to our systems as voltage surge absorbers, not voltage sustainers.

What would happen in a brown out?  If the voltage falls below the critical voltage for an item, it switches off until the voltage rises above the critical point and it comes back on again.  If the rx is subject to a brown-out, it initially switches off.  That means it generates no signal for the servos because it can’t pass on either the Tx signal or generate a failsafe signal.  In that case the ESC will switch off power to the motor.  When that happens you would have noticed it immediately and the voltage will rise rapidly so the rx switches back on and starts its boot up.  The early Spektrum rx took several seconds to boot up hence the crashes, but since that problem was diagnosed the design was changed and for a long time the Spektrum rx have booted up very quickly.  So if you had a brown you would have noticed the motor lost all power and the radio quickly coming back on.  If the throttle was left where it was then the motor would have promptly dropped the battery voltage low and the whole cycle would repeat.  You simply could not fail to notice the motor hunting rapidly on and off and control of the model coming and going just as rapidly.  You did not say anything about that so on the assumption it did not happen, you did not have a brown-out of the rx.

You may have had a brown-out of one or more servos.  Say what?  Yep, many rx now have a critical voltage that is lower than many servos, so the rx carries on working and reporting via the flight logger or telemetry that everything is working, but the servos won’t move because the system has gone below their critical voltage.  As long as the ESC’s critical voltage is below the system voltage, like the rx it will still work.  So the rx and ESC still work, the motor is running, but all the servos have stopped, and because the motor is still running it keeps the system voltage below the servos’ critical voltage.  That’s a bit more plausible for what happened to you, though I don't think it would have been as I expect you tried to shut the motor down and it did not respond.

Phil  has already explained why the capacitor is no use against a very brief Rx brown-out and it would have no hope of providing the several seconds or minutes of voltage required to overcome a servo brown-out.  So what are they for?  I said they are surge preventers.  Multiplex explains what they are for – if you have powerful digi servos they can create a dynamo effect and pump voltage spikes back along the servo wires to the rx.  No problem, the battery soaks them up.  But if you have diode battery backer such as was factory fitted to many Multiplex rx or such as the SM Services backer, the diode isolates the battery and the spike has nowhere to go but into the Rx’s circuits and could damage the Rx.  Hence Multiplex sells the big capacitors to absorb the spike and protect Rx when a diode battery backer is being used.  The notion that the capacitor can store enough energy to maintain system voltage during a brief let alone an extended brown-out is wishful thinking!

Therefore leccy, if I were you I would have no confidence that your problem has been correctly diagnosed and zero confidence that the capacitor has fixed it!

[leccyflyer]

Leccy, what you describe does not match a voltage brown-out on the rx, so several things follow from that:
1.You need to find the real cause, because if it wasn’t a classic brown-out then a brown-out preventer device has not fixed it.

2.Capacitors are not brown-out preventers anyway as has been ably described by Phil

3.Capacitors are fitted to our systems as voltage surge absorbers, not voltage sustainers.

What would happen in a brown out?  If the voltage falls below the critical voltage for an item, it switches off until the voltage rises above the critical point and it comes back on again.  If the rx is subject to a brown-out, it initially switches off.  That means it generates no signal for the servos because it can’t pass on either the Tx signal or generate a failsafe signal.  In that case the ESC will switch off power to the motor.  When that happens you would have noticed it immediately and the voltage will rise rapidly so the rx switches back on and starts its boot up.  The early Spektrum rx took several seconds to boot up hence the crashes, but since that problem was diagnosed the design was changed and for a long time the Spektrum rx have booted up very quickly.  So if you had a brown you would have noticed the motor lost all power and the radio quickly coming back on.  If the throttle was left where it was then the motor would have promptly dropped the battery voltage low and the whole cycle would repeat.  You simply could not fail to notice the motor hunting rapidly on and off and control of the model coming and going just as rapidly.  You did not say anything about that so on the assumption it did not happen, you did not have a brown-out of the rx.

You may have had a brown-out of one or more servos.  Say what?  Yep, many rx now have a critical voltage that is lower than many servos, so the rx carries on working and reporting via the flight logger or telemetry that everything is working, but the servos won’t move because the system has gone below their critical voltage.  As long as the ESC’s critical voltage is below the system voltage, like the rx it will still work.  So the rx and ESC still work, the motor is running, but all the servos have stopped, and because the motor is still running it keeps the system voltage below the servos’ critical voltage.  That’s more plausible for what happened to you.

Phil  has already explained why the capacitor is no use against a very brief Rx brown-out and it would have no hope of providing the several seconds or minutes of voltage required to overcome a servo brown-out.  So what are they for?  I said they are surge preventers.  Multiplex explains what they are for – if you have powerful digi servos they can create a dynamo effect and pump voltage spikes back along the servo wires to the rx.  No problem, the battery soaks them up.  But if you have diode battery backer such as was factory fitted to many Multiplex rx or such as the SM Services backer, the diode isolates the battery and the spike has nowhere to go but into the Rx’s circuits and could damage the Rx.  Hence Multiplex sells the big capacitors to absorb the spike and protect Rx when a diode battery backer is being used.  The notion that the capacitor can store enough energy to maintain system voltage during a brief let alone an extended brown-out is wishful thinking!

Therefore leccy, if I were you I would have no confidence that your problem has been correctly diagnosed and zero confidence that the capacitor has fixed it!

I don't have any great confidence that the problem has been solved - in common with the title of this thread - but the basic idea of the capacitors made sense, to me. From the explanations above it sounds like it might be a case of snake oil and that I've wasted a few quid.

The motor was definitely running at impact, so the failsafe didn't kick in or that would have shut the motor down and put surfaces to neutral. The motor wasn't hunting, it was just running, as normal. The model hit the ground on the third power-on loop. I watched my son stir the sticks, in front of us, and there was zero response from the model, it continued to make a third loop and impact the ground.

The receiver is going back to Horizon for testing. It's worked fine for over a year and it still works now, after the crash, as do the servos. The model is trashed and has been binned. I don't have any confidence that I'd get anything other than a replacement receiver, if that, wheras what I'm really after is an explanation or identification of a actual fault. I reiterate that the model has flown without a glitch or a hitch for over a year, since the installation of the Spektrum receiver - that follows several years of flight with a 35mhz receiver. As I described in an earlier post on it's penultimate outing it had shed an elevator, in the air, which had been replaced. The repair is sound, undamaged and works as per normal, even after the crash. The cause of the crash remains unsolved, but the pointers are towards the radio system - I'm convinced that it was not pilot error, nor a mechanical failure.

I hesitate to even bring this up but I did note subsequently to this incident that we do appear to currently have an FPVer in our midst in this part of the world, with a reported 500mW airborne transmitter and a penchant for flying off-piste and posting the results on You Tube. I would have imagined though that the 2.4Ghz system would be sufficient to reject any such interference unless it was very close. One of the sites where this chap has been flying is within visual range of our club site, though about 2.5 miles as the crow flies we used to be able to see the landmark. I'm not making any connection to that, however.

[bobt]

I don't have any great confidence that the problem has been solved - in common with the title of this thread - but the basic idea of the capacitors made sense, to me. From the explanations above it sounds like it might be a case of snake oil and that I've wasted a few quid.

The motor was definitely running at impact, so the failsafe didn't kick in

I hesitate to even bring this up but I did note subsequently to this incident that we do appear to currently have an FPVer in our midst in this part of the world, with a reported 500mW airborne transmitter and a penchant for flying off-piste and posting the results on You Tube. I would have imagined though that the 2.4Ghz system would be sufficient to reject any such interference unless it was very close. One of the sites where this chap has been flying is within visual range of our club site, though about 2.5 miles as the crow flies we used to be able to see the landmark. I'm not making any connection to that, however.

hmm- sounds dodgy, but WHY NO FAILSAFE? 

[Harry formerly mpx]

That was my feeling too Bobt.  The reports about illegal fpv activity are disconcerting, but a model shot down by one must come down in failsafe.  If it is not in failsafe, it was not shot down by fpv or any one of the other legal uses of the ISM band.  If it was not in failsafe then the rx thought it was getting a valid signal with its GUID, or the rx went faulty.  As leccy as alluded to, was it the "AR500 thing" or is that unfair on that rx?  The model was not in failsafe so it was not shot down.  Structural failure or dumb thumbing are options, but since the sticks were waggled and nothing happened and the motor continued, they don't seem to apply in this instance.  It looks more and more like the rx went off with a mind of its own.  Not a nice thought since it could happen in the pits.

[leccyflyer]

..and that's the worry, given that I've got a bunch of those receivers and have been using them for over a year without a single problem. If it was a poor installation, or poor battery set-up - which is what I'd attributed the only examples of AR500 "failures" that I'd happened across previously, from other flyers - then I could understand it, but this doesn't really fit the symptoms.

[Thoughtful_Flyer]

..and that's the worry, given that I've got a bunch of those receivers and have been using them for over a year without a single problem. If it was a poor installation, or poor battery set-up - which is what I'd attributed the only examples of AR500 "failures" that I'd happened across previously, from other flyers - then I could understand it, but this doesn't really fit the symptoms.

As I mentioned in another thread I've seen several problems with these receivers in installations that had been carefully checked.

On two occasions contact was regained after several seconds of "brown out" so the plane returned undamaged. No amount of battery checking or fault finding by "experts" cam up with the problems.

Two more, bought brand new from the same dealer at the same time showed obvious faults on the ground and were returned.

One regularly took up to ten seconds to bind. The other lost its bind three times in the pits whilst the engine was being setup.

[Seaking]

What Transmitter are you using

Roger

[keithupnorth]

Been some interesting reading since my origional post,as an update my club have been doing a little digging and are actively trying to ascertain if their is a problem or not ( seems one or two names and places come up regularly?)
but in the meantime and credit to the club they have purchased two scanners,and whislt it may not prevent the possibility of swamping it could confirm it, I on the other hand have renewed my module and bought a few more recievers, mainly I admit for a personal confidence reason, I will stick with 2.4 as I genuinely felt attached to my planes with it, I dont lose many models in fact this only the second in quite a while, and its not a nice feeling especially the not knowing bit, how some who seem to lose models regularly   just pick themselves up and start again is beyond me.

cheers KW

[Arceenut]

Have you checked VERY THOROUGHLY the supply wiring?  The symptoms would indicate a complete loss of power rather than a brouwnout OR RX/TX failure. Check the supply switch thoroughly.  The same problems are there whether you are on 2.4 or any other band. Any loose or dodgy plugs or socket on the wiring or plugs? How old are the switches and wiring? A problem not meantioned lately is the "black corrosion" thing that plagued battery wiring in the past?

[Harry formerly mpx]

Have you checked VERY THOROUGHLY the supply wiring?  The symptoms would indicate a complete loss of power rather than a brouwnout OR RX/TX failure. Check the supply switch thoroughly.  The same problems are there whether you are on 2.4 or any other band. Any loose or dodgy plugs or socket on the wiring or plugs? How old are the switches and wiring? A problem not meantioned lately is the "black corrosion" thing that plagued battery wiring in the past?

It's not that.  Remember leccy said the motor carried on running.  If power to the rx was cut it would stop generating a data signal to the ESC, and the ESC's safety would promptly cut the motor.  This rx carried on sending a data signal to the ESC so the rx was powered, it didn't go into failsafe, it stopped responding to the tx and it locked the controls where they were.  Not a good omen!

[leccyflyer]

Have you checked VERY THOROUGHLY the supply wiring?  The symptoms would indicate a complete loss of power rather than a brouwnout OR RX/TX failure. Check the supply switch thoroughly.  The same problems are there whether you are on 2.4 or any other band. Any loose or dodgy plugs or socket on the wiring or plugs? How old are the switches and wiring? A problem not meantioned lately is the "black corrosion" thing that plagued battery wiring in the past?

The wiring is fine. It's an electric powered model, with the lipo battery pack - also used in half-a-dozen similar models - taken out when not actually being flown. The on-board electrics are several years old. The model is stored hanging up in a centrally heated room. No symptoms of blackwire corrosion, no evidence of any degradation of the power supply cables. A decent quality switch fitted on the radio side - through a BEC - which functions perfectly on the bench. Harry's description is correct - the model didn't go into failsafe and kept the last position of the controls - up elevator and high throttle - after control was lost.

[bobt]

It's not that.  Remember leccy said the motor carried on running.  If power to the rx was cut it would stop generating a data signal to the ESC, and the ESC's safety would promptly cut the motor.  This rx carried on sending a data signal to the ESC so the rx was powered, it didn't go into failsafe, it stopped responding to the tx and it locked the controls where they were.  Not a good omen!

If that is the case, it then becomes a problem in the ESC, surely? Without a good signal, the Rx would failsafe, it did not. Without power to the rx, the ESC would have cut the motor. Therefore there was a signal, and power to the motor, finger points to the ESC....but would that cause control loss? If not, then the failsafe did not work as planned. Whatever happened, interference, loss of battery power, failure in some hardware, then either the Rx failsafe or the Esc safety protocol should have cut power. What else could cause that?

[JohnB]

It's not that.  Remember leccy said the motor carried on running.  If power to the rx was cut it would stop generating a data signal to the ESC, and the ESC's safety would promptly cut the motor.  This rx carried on sending a data signal to the ESC so the rx was powered, it didn't go into failsafe, it stopped responding to the tx and it locked the controls where they were.  Not a good omen!

That would tend to suggest a problem with the analogue (stick position) side of the Tx, i.e. the Tx didn't process new stick positions but continued transmitting the current positions.

J

[bobt]

That would tend to suggest a problem with the analogue (stick position) side of the Tx, i.e. the Tx didn't process new stick positions but continued transmitting the current positions.

J

good point!

[leccyflyer]

Hope not - it's bad enough to have a question mark placed over half-a-dozen receivers, without having one placed over the transmitter (which, incidentally, has performed faultlessly in five different models over the past week).

[propeak]

Ok im'e going to add a bit more confusion to this thread, the supposion is that if the esc looses a valid signal from the rx it automaticly shuts down the motor, well i knew for a fact that some of the cheaper chinese controllers i have don't shut the motor down if i switch the tx off, anyway i just got one of my models out thats equipt witha jeti advance 40 amp esc same as was in leccys spit, the model is on frsky as all my models are now, failsafe was set i powered up switched off the tx and the motor immediately shut down, i did a rebind to cancel the failsafe and powered up again switched off the tx and guess what? the motor kept running just like the cheap chinese controllers, would anyone else care to confirm my findings?

[PDR]

Is this not simply showing that the Frysky Rx, when it has no specific failsafe settings, will do a "hold last position" in response to signal loss? If so then the Rx continues to send a "good" throttle signal to the ESC.

Certainly my experience with "dumb" 35MHz receivers is that as soon as the Tx signal is lost and no servo signal is sent to the ESC and the Jeti ESCs will *always* cut the motor without a signal from the Rx.

PDR

[Yoyo]

Is this not simply showing that the Frysky Rx, when it has no specific failsafe settings, will do a "hold last position" in response to signal loss? If so then the Rx continues to send a "good" throttle signal to the ESC.

Certainly my experience with "dumb" 35MHz receivers is that as soon as the Tx signal is lost and no servo signal is sent to the ESC and the Jeti ESCs will *always* cut the motor without a signal from the Rx.

That's what I was just typing when you said it...

'Throttle' isn't always throttle (for me it's crow braking) so a hold last position is the safest option if you don't set the failsafe specifically.