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Gas Engine interference

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Old 09-12-2012, 05:33 AM
  #51
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Default RE: Gas Engine interference


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ORIGINAL: Len Todd



Did you use a non-conductive throttle linkage? A conductive throttle linkage has been known to ''feed'' ignition noise into the throttle servo and back to the receiver. Also, if you are using ganged Aileron servos (i.e. two on each wing): On my 33% Extra 300L, I separated the ganged aileron servos using smartfly's Equalizer II. They acted erratically w/o the Equalizer in between the AR9210 receiver and the servos. I could not just use Ys on ganged digital servos.

Another old modelers tale with no basis in fact. You can use anything you want as long as its isolated from the engine with a plastic quick link. Even on 72mhz
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Old 09-12-2012, 06:33 AM
  #52
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Default RE: Gas Engine interference

Non-conductive = isolated/insulated/whatever. Sorry, if my N-Plant electronics technical jargonconfused you.


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ORIGINAL: dirtybird
Quote:
ORIGINAL: Len Todd


Did you use a non-conductive throttle linkage? A conductive throttle linkagehas beenknown to''feed'' ignition noise into the throttle servo and back to the receiver. Also, if you are using ganged Aileron servos (i.e. two on each wing): On my 33% Extra 300L, I separated the ganged aileron servos using smartfly's Equalizer II. Theyacted erratically w/o the Equalizer in between the AR9210 receiver and the servos. I could not just use Ys on ganged digital servos.

Another old modelers tale with no basis in fact. You can use anything you want as long as its isolated from the engine with a plastic quick link. Even on 72mhz
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Old 09-12-2012, 06:15 PM
  #53
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Default RE: Gas Engine interference

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ORIGINAL: Len Todd

Did you use a non-conductive throttle linkage? ...
If you are referring to me and my difficulty with the RCEXL opto kill switch, the answer in this case is yes.
However, most of the time I use a conductive flexible metal cable passing through a thin plastic tube because it is easier to route it around obstacles without binding. For short direct linkages I use a conductive metal rod as shown in the picture. In all cases there is no metal rubbing against metal at the ends or anywhere between.
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Old 11-02-2012, 02:58 PM
  #54
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Default RE: Gas Engine interference

If you have problems with strong ignition interference RCxel would not help because like soameone said wires in it are too close. Remember to use at least 10" of galvanic sepration, some nylon pushrod on throttle, and independet battery for ign and rx circuits. If you have to set throttle servo near engine you can find interesting of using a "setlo" FORCE Servo Controller, its a fiber optic transmittion of servo control, they also have a FORCE Ignition Cutoff with Fiber optics, and some nice functions that add some points to safety rather than S-F, and /i think its more rugged.
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Old 11-03-2012, 06:59 AM
  #55
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Has anyone ever lost a plane with CDI interference being the "smoking gun" or even tested to ID potential CDI interference (e.g. searching for it with an RF Monitor or O-scope, etc.)? If so, please let us know!

One has to wonder about the claimed potential effect that a CDI can really have on a Rxer, when telemetry's direct connections seem to subvert any isolating design (non-conductive throttle linkages, fiber-optic kill switches, separate batteries, etc.) we build in. Also, according to Andy, there is no buffering (to break direct connections) in the telemetry modules. So , ...Maybe some manufacturers are just hyping this potential effect to sell isolation devices? Maybe the CDI manufacturer's warnings of this risk are just disclaimers to address potential effects that some manufacturers' old 72/75 Mhz engineers cling to? Maybe these warnings really only apply to 72/75 Mhz? At any rate, the addition of telemetry's direct connections (e.g. RPM Sensor) w/o any definitive negative effect on the 2.4 Ghz Rxer, certainly has lowered the probability of the "CDI 'noise' may interfere with the Rxer" risk.

Or, ... is building a giant scale gas plane like building an N-Plant? The design addresses every possible risk, no matter how low the risk's probability actually is, by either precluding the risk or having the risk's contingency built in ready to automatically function. We pay a lot more for a plane (and N-Plants) when we do this! It also limits some of our choices. Maybe, most smaller gas planes simply are not worth the added cost, etc.?

The probability of a CDI interfering with a 2.4 Ghz receiver utilizing spread-spectrum communications seems rather low to me, especially since we added telemetry apparently w/o any increase in negative effect. The risk may be higher for 72 and 75 Mhz analog Rxers. ? Maybe building a 2.4 Ghz plane to preclude this risk is no longer worth the added cost? Do not get me wrong, being an old N-Plant guy, I still design and build to preclude the risk. But, that design precludes me from flying with telemetry simply because of the potential for increased risk that the telemetry adds to the plane. No one, including Andy, will tell me that the risk is no longer valid, even with 2.4 Ghz.

So, ... we keep building with all the extra junk we need to preclude this risk. Maybe the risk's probability is now low enough to merit just taking the risk? It is times like this I wish I had bought that UHF RF monitor I was "eyeballing" a few years back.
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Old 11-03-2012, 07:30 AM
  #56
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Default RE: Gas Engine interference

You are right, All we are doing is just because you dont know when it will happen to you, and we dont want it.
i found some video http://www.youtube.com/watch?v=7pVeijWm-dg
CDI ignition problem still occures even with 0,5 meter distance from it? there must be some major problem with it..
I'm using FORCE optic kill switch because its alternate to kill engine even when receiver will be dead when i have no control with throttle or choke servo.
If something will happen at the field i have my club insurance but if someone will ask was the circuit safe to put it in my plane? Its only my choise, and i know that i did
my best to minimalize it gaining some more safety functions, other thing is that i'm using doubled independent A123 with dobuled main switches for receiver with no regulators, and another A123 pack for ignition.
This summer one of my regulator dies during setup at my workshop soo ... i dont want another one.
I know its a little heavier now but i have more smile on my face when I can be more calm during each flight ... every one is making their own choises and own habits to do it "right"
this is just my way.

I have some nice electronic stuff in work so maby i'll make some tests with CDI noise with oscill.. or spectrum analizer. I can check it on futaba, JR, DSM, and hitec, with DA, MVVS, RCexl ignitions but it will take some time,, I'm also curious.

Sorry for my english
BR
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Old 11-03-2012, 08:57 AM
  #57
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Default RE: Gas Engine interference

I have not yet seen any Receiver blinking on my gas planes. I am using AR 9210 Powersafe receivers. I did have one fail yesterday, though. But the plane was still flyable and landed in one piece w/o event, even though the rudder was twitching. Guess the Powersafe features actually work, etc.

I have seen one of my Electric Planes (Parkzone T-28 with AR 600) with post-flight receiver blinking though. Apparently, there really is a reason for checking the Receiver post-flight before disconnecting battery! On the T-28, I just repositioned the antennas and have not seen the receiver blinking since. I also changed the Battery in the DX8 to the 4000 mah LiPo at the same time. The OEM 2000 mah NiMh battery was not holding a charge very long. However, I do not think that the transmitter battery was impacting my case. However, in the video he did not say he confirmed the correct battery voltage in his two transmitters, etc. But, looking at his shop, I assume he knows to do that.

In that video, the engine could be putting out enough RF signal to jamb/interfere with the transmitter's signal. I bet if he put a data reader on the receiver he would see the hold(s) and or frame losses that were recorded. It could also only be that there was only enough holds recorded, etc., on initial startup to set off the Rxer's LED. Maybe starting the Engine and then energizing the Rxer would yield a different result? My bet is he has an ignition system starting to fail. But. it could be the spark plug that has failed or it is not the resistored version of the plug. There could be a bad connection to the plug in the cap. If there is arcing in the cap there will be stray RF.  Maybe the cap has failed. Not sure what type cap he has. But some have resistance built in.  Maybe the plug wiring is failing and arcing to the SS sheath he installed over it? Maybe the sheath is arcing to the engine? Maybe the ignition source itself is failing?  I did not notice if it was a Mag or CDI. I have seen a Mag short to the case and arc in a snow machine. A failing CDI unit can put out stray RF. Lots of things to check for. We have some of the same type ignition problems on our snow machines that usually show first up in stray RF. On them there is no handy receiver to show that you have an RF problem. 

Because of theT-28 incident described above, I picked up a Receiver Data Reader last week. I just have not yet had the time to fiddle with it. This may be where such a device becomes useful.
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Old 11-07-2012, 02:55 PM
  #58
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Default RE: Gas Engine interference

In this case, when servo's start moving by themselves, like described the aileron servos did, it doesn't have to do with 2.4 GHz or 35MHz at all.

Look at what controls the servo position; A puls width. Just look at it with an oscilloscope. The length of the pulse gives the position of the servo.

Disturb that pulse witdth, and the servo start moving.

The pulse width is in the millisecond range. Milliseconds, thats KHz, not GHz.
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Old 11-07-2012, 07:11 PM
  #59
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Default RE: Gas Engine interference


Quote:
ORIGINAL: okier

If you have problems with strong ignition interference RCxel would not help because like soameone said wires in it are too close. Remember to use at least 10" of galvanic sepration, some nylon pushrod on throttle, and independet battery for ign and rx circuits. If you have to set throttle servo near engine you can find interesting of using a "setlo" FORCE Servo Controller, its a fiber optic transmittion of servo control, they also have a FORCE Ignition Cutoff with Fiber optics, and some nice functions that add some points to safety rather than S-F, and /i think its more rugged.

This............. . http://setlo.com/
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Old 11-07-2012, 07:26 PM
  #60
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About using a "Y" harness to reverse sero direction. It is better too buy reversed servoes and are good to have on hand. Capt,n
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Old 11-08-2012, 08:56 PM
  #61
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Default RE: Gas Engine interference


Quote:
ORIGINAL: okier

If you have problems with strong ignition interference RCxel would not help because like soameone said wires in it are too close. Remember to use at least 10'' of galvanic sepration, some nylon pushrod on throttle, and independet battery for ign and rx circuits. If you have to set throttle servo near engine you can find interesting of using a ''setlo'' FORCE Servo Controller, its a fiber optic transmittion of servo control, they also have a FORCE Ignition Cutoff with Fiber optics, and some nice functions that add some points to safety rather than S-F, and /i think its more rugged.
RCEXL Ignition would cure the RF problem.We replaced a lot of the Ridge Igns with C&H or RCEXL. I have a First place 2.4 with my ignition of course and it is a great little engine.Kurt at FPE changed to the C&H system years ago.Have not heard from him
Nice guy last time I talked to him he was going to sell Chinese engines.I told him to be careful,be very careful.
BC CHI
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Old 11-09-2012, 06:21 AM
  #62
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Default RE: Gas Engine interference


Quote:
ORIGINAL: okier

...

This............. . http://setlo.com/
On a side note: SmartFly's Fiber-Optic Kill Switch now has the Voltage Regulator built in so that you do not over do the voltage to the CDI even with 2S LiPos. But, ... I am not so surea voltage regulatoris even needed. I have dozens of hours on my DLE 111with 8.4 VDC on the CDIand it is still flying. Spec for this particular CDI is up to 9 VDC.

Back to thetopic: I have aFiber-OpticKill switch in the Extras. But, I am not so sure they areeven needed. I also have telemetry and ithasa couple direct connections to the Engine/CDI and one direct connectionto the receiver andtelemetry is not electrically buffered/isolated. The plane has been flying fine with the telemetry'sdirect connectionsconnected. I suspect2.4 Ghz Rxersarenot affected by the CDI. Maybe on this new build I am working on I'll do some testing without the FO Kill switch and see if its absencechanges Frame losses or Holds, etc.
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Old 11-10-2012, 12:32 AM
  #63
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Default RE: Gas Engine interference

Hello,guys
i am a representative of the DLE manufacturer ,and this is my first time to come here.
So hope i can learn and share something about DLE in here.

If you have any question,please feel free to ask me. I will try my best to help you.
But i donot know that(because i am also a newer for engines, i am also learning about DLE)

Thanks for your attention and support about DLE.
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Old 11-10-2012, 01:30 PM
  #64
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Default RE: Gas Engine interference


Quote:
ORIGINAL: DL826

Hello,guys
i am a representative of the DEL manufacturer ,and this is my first time to come here.
So hope i can learn and share something about DEL in here.

If you have any question,please feel free to ask me. I will try my best to help you.
But i don't know that(because i am also a newer for engines, i am also learning about DLE)

Thanks for your attention and support about DLE.
How can we feed a DLE 111 CDI's Tach output into Spectrum's Telemetry thus precluding theneed for an addedRPM Primary Element/Sensor? Some of the guys are using a Y on the CDI's harness to the Hall Effect sensorcircuitand route the "signal"back to the Telemetry Module. This sets up a direct wired connection back to the receiver which IMHO is NOT desirable. I would like to see a connection to the CDI's Tach Output and hear that the CDI'sTach output will not negatively impact the receiver, even though it too is a direct connection.

Also, I suspect there is also a grounding issue here in that some of the guys can get the Y harness approach to work and some can not. I suspect that ifone isusing a separate battery and Fiber-optic Kill switch, to get a signal, one has to include a ground wire connection along with the Hall Effect "signal"conductor. However, if they are using a BEC, the ground connection is already there VIAthe BEC. Is this correct?

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