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They are in a portion of the electromagnetic spectrum that simply does impact on the 2.4GHz equipment
yep shows are ditching 35 just so they don't have to pay people to run the TX tentso 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 upi 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 do not think Tx control cost is the issue to organisers
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.
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.
Well my RF is a bit rusty, but here goes:
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
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 mAhA 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. CheersPhil
PhilYou 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?
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?
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 Phil3.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 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.
..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.
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!
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
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.