EDF interference

[Tentpeg]

Can anyone tell me how to avoid interference when operating an EDF such as the Fantom. This model was finally written off as a result of bad glitching and subsequent disorientation. I am planning to cannibalise the main components and build one of the EZE-Fans as featured in July RCM&E, but want to sort the interference problem out first. Any ideas without resorting to an expensive PCM receiver??
Regards,
Tentpeg.

[Tim Mackey]

PCM will not neccessarily solve your problem, but may well mask it. Fit the best quality rcvr you can ( schulze alpha, Mpx IPD, or Jeti IPD all give good results in EDF. Keep the receiver as afar as possible from the ESC, and also the motor. Fit ferrite rings on all leads just where they enter the receiver.
I eventually reduced my glitching Sabre EDF to an almost acceptable level by doing all these things, but my complete cure came only when I fitted the Spektrum 2.4Ghz system. BRILLIANT
check out this thread on the exact same subject
http://www.modelflying.co.uk/forum/forummessages.asp?dt=1&UTN=726&last=1&V=6&SP=

[Chris Dickens]

Timbo
All any of your receivers are doing is masking or filtering the glitching. Don't have such a downer on PCM.
A PCM receiver will be doing EXACTLY the same as your favorite IPD one and that is ignoring the rubbish and accepting the good signals.
2.4 Ghz is well above the frequency of any signals from you motor/EsC/battery setup. that's why it doesn't glitch. I could be negative about 2.4GHz as I have lost two models due to a dodgy transmitter but I am not. It's definitly the way forward.

[Alistair Taylor]

You could always use a glow engine...

(lights blue touchpaper and runs....)

Try an opto-isolator as well - they're not expensive, although you will need a separate RX nicad.


AlistairT

[Tentpeg]

I don't follow, why I would need a separate RX nicad. Could you give some indication how it would all be connected together. I do apologise, but I have only recently made this cautious excursion into the electric powered world and am a bit of a dumbo.
Regards,
Tentpeg.

[Alistair Taylor]

No worries

An opto isolator is a device that converts the electrical signal from the Receiver into an optical signal (think Infra red TV remote control), which is then picked up by an optical receiver (think IR receiver on the Telly), converted back into an electrical signal and passed on to the electronic speed control (ESC).

The point of an opto isolator is that the transmitting side (the RX) and the receiving side (the ESC) are electrically isolated - they do not share ANY electrical connections, and so any interference that is making its way along the cables between the RX and ESC is eliminated.

What this means is that the opto-isolator (which plugs in between the ESC and the TX) cuts off the BEC supply to the RX. So you need to plug in a separate battery to the RX in order for it to work.

You could be forgiven for thinking that this rather negates the advantage of having a BEC in the first place, as well as the weight saved by using lipos, but the actual current draw on the RX battery is very low, so you can use a very small (and lightweight) battery for this, e.g. 1/3 AAA.

This is a rough and ready explanation, and if you're after a more detailed/technical one I'd urge you to google opto-isolator and browse what comes up at your leisure.

AlistairT

[Alistair Taylor]

See;

Mtroniks Zero Glitch Module (i've use this, it works);

http://www.mtroniks.net/mtroniks_products.asp?CategoryID=11&SubCategoryID=38

Wiki info (bit techno);

http://en.wikipedia.org/wiki/Optocoupler

NE Sailplanes product (haven't tried this one);

http://www.nesail.com/detail.php?productID=5129&PHPSESSID=5c2ea6530ec2967a237

[Tentpeg]

Many thanks for the info, Alistair I'll have a look at it.
Tentpeg.

[Tim Mackey]

Chris. I am aware of the reasons for 2.4Ghz being so successful in my electrics thank you. As far as my comments re: PCM versus PPM I stand by my claim that PCM can often mask a glitch from being visible, whereas a regular PPM receiver will often show it in the flight. I merely recommended the IPD receivers because they have proved very reliable and trouble free in some earlier models, where "regular" PCM ones have not.

[nasa_steve]

hi tentpeg
can i ask if you have extended any of the esc cables and if so which ones?? secondly since when has pcm been expensive you can get a pcm receiver for under £40 although that does depend on which radio gear you use.
regards
nasa

[Tentpeg]

Hi there, Steve.
There is an extension on to the receiver, but nothing else. It's all a bog standard package as supplied with the Fantom. I may be able to get away with a slightly shorter extension with the EZE Fan, but I don't think I will be able to do without any extension at all.
I will try the opto isolator as recommended by Alistair and hope that does the trick. I've looked them up on the mtronics site and they are very cheap (under a tenner). Thanks for all your advice chaps. I will get back and let you all know how it works out.
Regards,
Tentpeg.

[Alistair Taylor]

Tentpeg

Don't be tempted (like I was) to cut/disconnect any of the cables from the speed controller to the Mtroniks GFM. It relies on the BEC supply from the speed controller to power the motor side of the electronics.

AlistairT

[Tentpeg]

Thanks for the advice. I had planned to connect the speed controller, via the Opto device into channel 3 on the Rx and use the spare channel4 for the supplementary power supply. I have a small NiMH battery for this purpose. How small can this battery be?
Regards,
Tentpeg.

[Alistair Taylor]

Tentpeg

A 300 MaH 1/3 AAA NiMH pack should be OK.

See overlander's website.

AlistairT

[Tentpeg]

Many thanks Alistair, I will let you know how it goes,
Tentpeg.

[scott cuppello]

Ah yes, EDF's and glitching....it's why Iv'e given up on them until I can justify buying a 2.4ghz radio.....Iv'e lost 2 models to this problem [which seems to just go hand in hand with EDF], Jeti reciever and ferrite rings have cured it on everything else.

[Alistair Taylor]

Scott

You are not alone

See the posts on the other EDF thread.

I was toying with the idea of EDF, but if it's going to total an otherwise perfectly flyable model I'm not inclined to dip my toes in the water just yet.

AlistairT

[scott cuppello]

I keep saying this, EDF is being hailed as they next great thing....but a LOT of what is being sold curently is, no other word for it.....rubbish.

Had a BAE Hawk [not going to mention names], but ESC and motor supplied, it turns out, had a life of aound 3 mins....not impressed [as was anybody else], stick in replacement ESC, motor fan, only to loose it to glitching, 2nd flight.

Latest offering from Kyosho....lost to glitching, but was [in my opinion], far, far too expensive, silly sensitive to C of G [2mm!], really dumb battery tray, dumber canopy, so small it's nearly impossible to move stuff to get shut of glitching, tip stalls like a pig....er, great investment!

CC Lee Me262 & GWS A10....basically don't fly as they are!

So, I'll stick with props until the manufacturers, importers & retailers can get their act together.

[David Ashby - Moderator]

Just as an aside to the many very useful points. I've used a little jeti MPD (Yellow) receiver in my F20 (see article in this issue) and it has been very good. I was very worried about glitching especially with those long battery leads but so far so good. I'm very impressed with all things jeti, never had a prob' with their gear.

[Tim Mackey]

I agree with you, Jeti are indeed top class gear.

[scott cuppello]

I switched to Jeti on another model because of my paranoia about glitching, they are great but don't cure, rather mask the problem.....safe[r] but still irritating, and I'm sure 2.4ghz is the way forward with "serious" EF.

My EDF's were all brushless, Iv'e long since given up on brushed motors, Nimh batteries and all things old hat!

The failures of stuff like the Hawk were down to the utter rubbish fitted by the factory, and Iv'e read on another forum the same story with just about anybody who bought one. I also believe some motor failures have happened on the Kyosho....not very funny on a plane known to tip stall for fun, and my glitches with it were mainly motor cutting out, resulting in minor prangs, but the one that did it in was a total lack of control over servo's in the end.

As much as anything, it wouldn't be as bad if they were park flyer prices, but you are seeing regular prices of around £120 for the new ones [EDF's] for a peice of foam with a glorified hair drier stuck in the back!

Many at our club are interested in EDF [jet's are becoming popular, but not the price], but I can assure the importers [hoping they read this] that nobody is interested in spending £500 [what it would cost someone starting out in EDF from scratch] on building a 38" foamie! Get realistic!

[Tim Mackey]

John, I have responded to this comment over in the VERY similar thread "EDF glitching."
I do wish the moderators would merge some of these very similar threads, and have better categorisation....quite a few things about the forum layout I dont like.

[scott cuppello]

John, sorry, but I don't really accept your theory, certainly in my instance, no linkeage slop was there, no cheap servo's, in fact no cheap anything. I have certainly found since that Ferrite rings help via some experiments, leading me to come to the conclusion that 3 & 4 cell Lipo's, combined with powerful motor/ESC's, in a small space, long motor leads, high rpm motors.....all the things EDF in other words....are very problematic....and for many..TOO problematic. I think that either 2.4ghz radio, or OPTO ESC's are more likely someway nearer what's needed in EDF's, more info/experimentation required, as it's obvious that at least as many people have suffered problems as those not...and I don't think a 50% "failure" rate is acceptable for many contemplating parting with hard earned cash.

What makes me mad is the sneaking feeling that those looking for our cash, are not ironing out those problems. For instance, I saw an EDF recently advertised at £119, a lot for a foam EDF/Motor and nothing else. Now then, they were advertising it with 5 cell lipo, this size ESC needed, blah, blah [interestingly, no reccomendation for an non BEC speed controller....?!]...then on another forum, the test pilot from this company comes on and states that this set up is rather rubbish and won't work! Not so good for those that rushed out and bought one eh?

[scott cuppello]

It doesn't annoy me at all, and I think it would be interesting to know what gear you tend to use? Why you don't have problems? In this respect, I think you could be very helpful, other than that, no offence, if you havn't suffered with it....it makes it difficult for you to help!

You are clearly an EDF fan [no pun intended], and I'm sure would like to see it progress, and that you ae pretty passionate about it. But, the experiences people like myself have had recently mean it's all going to fall flat on it's face as people, like myself, walk away, or other people, like my club mates, think....I'm not bothering with that...and believe me, there was plenty of interest!

Personally, I don't think it's ok to be sold something that is not very good, watch it crash and shrug my shoulders mutting "oh well, that's modelling"!

[Alistair Taylor]

John

I've asked this in the other thread;

What setups are you using?

Both threads were started by modellers wanting glitch-free EDF setups.

If you have a 9 out of 9 success rate with yours, I, personally, would love to find out what they are.


AlistairT