Tired Old Man

My Feedback: (1)

You'll play hell getting a product manufacturer to admit they have a problem with one or more of their products. I can name several instances where radio manufacturers have maintained denial of known servo issues, and where one manufacturer manages to get stupid people to pay for "upgrades" that are little more than patches for defects in their radio products. The interest of a manufacturer is not the same as that of the consumer. The manufacturer is concerned only with profit, especially in a field completely unregulated and unmonitored as RC hobbies. You have the option of believing, or not, the lies you are told about their high level of concern for the modeling consumer.

This is why I find the actions of Hitec to make a public statement to be extremely commendable. They make a statement referring to optical kill switches without naming a brand. The lack of brand has implications that should be easy to figure out. For people to try and seek an end around so they can avoid doing anything with their optical kill switch provides an indication of individual stupidity beyond comprehension. If you are using a Hitec A9 you should not be using an optical kill switch. They all work the same way. The only real difference between them is the brand name.

karolh

Even I was able to figure that out for myself

Karol

closetguy

My Feedback: (13)

never did like the idea of a optical kill switch pluged in to the rx.i use the A9 so far with 0 troubles,but i also use a throttle cut and a servo on the choke.i always keep it simple and try to stay away from the bolt on goodies stuff.

Tired Old Man

My Feedback: (1)

Before optical kills we had servos used to drive a switch for those that had such concerns. 99% of the time the throttle trim was plenty effective at killing an engine, with 95% of the 1% problem balance caused by user installation and set up error. Since the advent of the plug and play generation the user error percentages has risen appreciably. In never having to build they never had to learn how various components interacted and their association requirements.

Our gas engines shut down exactly the same way every other fuel powered engine does. Cut either the fuel, the ignition, or both and the engine stops. In full scale you cut the fuel. In your car you cut the ignition. Only modelers seem to have a need to make it complicated.

bkdavy

My Feedback: (1)

I'm going to keep an eye on this, because frankly I'm having difficulty thinking of a plausible mechanism for an optical kill switch to cause a problem with the reciever. There is very little difference between the optical kill switch and a servo, other than the action taken when it translates the signal from the reciever. Start adding in all the other bells and whistles (power expander boards, buffers, etc) and I start getting worried about all the other failure points.

I have not yet resorted to an optical kill. I do use an electronic kill switch of my own design with an Aurora 9 and an Optima 7 reciever, and am very happy with the entire setup. Cutoff controls a 5v regulator circuit that powers the ignition, so there are at least two barriers between the ignition and the reciever (regulator and cutoff). I found my system was FAR more subject to ignition interference when I was on 72 mhz. BTW, when I heard about this problem I did provide Hitec with a schematic for my cutoff circuit, as well as some observations I made while testing and a failure I experienced on the reciever on the bench. The Optima line of recievers have a built in voltage regulator, and I experienced a smoke release from the regulator (on the bench). Don't know if it was related to the cut-off switch or other issues. After the regulator failed, the reciever continued to function for a while, and then failed entirely. Had this happened in the air, obviously would have been a total loss. Anyway, it seems that if there is an issue, it will be with the Optima recievers, not the transmitter.

I'm still betting on a fault with the enduser setup, however.

Brad

Tired Old Man

My Feedback: (1)

Back when optical isolators came out I gave them a try in some high servo count installations. I have to say that was the first time I encountered serious signal interference to and from the servos. They weren't all they were cracked up to be. Right in there with toroid ceramic noise filters.

mstcitabria73

My Feedback: (1)

"Our gas engines shut down exactly the same way every other fuel powered engine does. Cut either the fuel, the ignition, or both and the engine stops. In full scale you cut the fuel. In your car you cut the ignition. Only modelers seem to have a need to make it complicated."



T.O.M.
That is the probly the shortest,simplest and most intelligent statement I've read in this thread yet, pretty simple and clear ....

hanko

No my intent was to call that a stupid remark

fritzdecat

Sorry but it was not a clueless remark as the thread has shown

K-Bob

My Feedback: (1)

Hmmmmm .

One method of killing the engine requires activating a circuit that drives a servo that pushes a link that closes a flap that eventually cuts off air to the engine. (if the linkage is setup right, if the carb is adjusted right)

The other uses a tiny light source to turn off a battery.

You tell me when it got "complicated"

A gazillion engine kill systems out there on a gazillion different TX/RX combos and one TX/RX comes up with a problem. I would tend to favor the opinion that the problem lies with the TX/RX not the optical kill.

fritzdecat

"A gazillion engine kill systems out there on a gazillion different TX/RX combos and one TX/RX comes up with a problem. I would tend to favor the opinion that the problem lies with the TX/RXnotthe optical kill."

vasek

My Feedback: (4)

Just my bad luck!

I have a JR 2.4 system for most of my planes, but just bought a Spectra module & receivers for my hi-end planes... before I bought Hitec, there were no problems reported... anywhere!

Blame me, I'm used to it. Whatever I buy, I have problems: refrigirators, TV, stove ... usually just days after the warranty expires [:@]

Just my Laptop and the Microwave have no issues at my home[&:]

I used to get mad. No more not worth my health.

Consider yourself(ves) lucky!
V.

K-Bob

My Feedback: (1)

Nah. My Futaba stuff has been, and continues to be, bulletproof. Previously on 72MHZ and now on 2.4GHZ. I just want to fly my model airplane as safely as possible and still have fun.

But,

You keep alluding to an inherent problem with 2.4GHZ and gas motors. Would you like to be specific or do you prefer the mysterious and cryptic approach?

fritzdecat

I called the guy at Electro Dynamics about his highly touted fiber optic kill switch which sells for $70+

He explained to me how there were many ways the information stream could be interupted.

Shielding at the spark plug cap

A messy arrangement of wires in the fuse

And a nebulous X-Factor as per the reasons stated by Tired Old man in post #47 of this thread


I am happy to hear your Futaba system is going strong, I had the opposite experience and went to Aurora 9

The only other thing I will ad is this adage....

"In every larger problem there is a small problem struggling to get out"

Campgems

Irecently bought some ignition modules and a couple of the Opto kill switches, all are RcExl origin. I've yet to install any of them so I'm looking at this thread as a way to learn something to prevent me some problems. As stated a little earlier, the RcExl kill switches just looks like another Servo to the RX. No way to get a signal messed up, but a potential source of EMI. Idecided to have a look inside one of mine.

The unit appears to be very well built for a start. Good clean solder joints and accurately placed components and wire. Other than a couple resistors and capacitors, there were only four ICs on the board. One is a Mos-FET switch, one is a PIC controller, and anothe is thesmall opto-isolator. I didn't get out the microscope and study the other, but my guess is that it is a voltage regulator for the Pic. I couldn't see any where that the input and output were coupled. All that said,the Opto is only about 1/8" square and as most everything associated with ignition states to keep a good distance between the ignition battery and module and the RX,here, we have a very close proximity.

The one thing I liked about the kill switch was the fail safe, IE if it quits being pulsed from the RX, it shuts off the ignition. Thinking about this, it would seem that a brownout on the RX would effectively result in a dead stick even if it was a short interruption. This quickly turns into the chicken egg question. Which came first. One other thing was the instructions showed how to use a BEC to provide power to both the RX and the kill switch/ignition with one battery. This looks like a sure receipt for a problem. The little manual,if you can call it that, shows how to jumper the ignition battery to the RX lead to power the RX. The "manual" was for V 1.3 and the unit is a V 2.0, I haven't been able to find the manual for the 2.0 to see if it is the same.

Don

Tired Old Man

My Feedback: (1)

Whoops!! I have to edit this. The person I was referring to was T-Bob, not K-Bob. They do appear to be related in some ways though.

All Day Dan

My Feedback: (5)

Don, Take another look at that kill switch. Envision that the wires to and from the ignition module is strewn with and electro-magnetic field that could contain radio frequency components that are in the band that you are operating in. If you're on 2.4 Gigahertz the wave length is around five inches. Now focus on the line going to the receiver. It's around five inches long. That's a perfect way to couple the RFI from the ignition right in to the receiver. Those little antennas from your receiver and transmitter for RF transmission and reception are called quarter wave stubs because they are a quarter of a wavelength long. There you have the potential of causing a massive interfering signal in to the receiver. TOM has been right in all his posts. Do not blame the R/C manufacturers. Their lively hood depends on them providing us with excellent equipment. The problem is with the guy buying it. Dan.

fritzdecat

All the rest is just chatter.

Campgems

Dan, from my days working with computers, there are two components to interference. RFI or radio frequency interference, and EMI Electro Magnetic Interference, which doesn't give a hoot what frequency the signals are on. Ignition falls into this later category. So does the Zap you get when you touch the elevator button. Think of it a lightening strike. Stray high voltage into the system can cause many unpredictable problems. We used to "Zap" a newly installed computer to failure. This was done by introducing a high voltage noise into the covers of the computer. At some level the computer would fail. No permanent damage, but just a stray "glitch" got in the mix and caused a failure. Most all of the noise was routed to building ground if things were installed right. The trouble with our planes is that there isn't a building ground, so isolation is the best solution. None of this has anything to do with radio frequencies, but rather stray voltages jumping into the circuits. Where they are coming from and what is failing with the Hitech A9 is yet to be determined. I think TOM is right., put the switches in a drawer until the problem is resolved, or an explanation by Hitec as to what is happening.

Don

All Day Dan

My Feedback: (5)

Don, I've been out of college for 50 years. I have forgotten more than I learned. I do know that you're not supposed to put a length of wire one wavelength long in to an electro magnet field and attach it to a receiver while the antenna that you're receiving your signal is 1/4 wavelength long. The guys should use the Smart-Fly switch if they think they need one. Dan.

Campgems

Dan, Me too.Not that I learned all the much there to begin with

The computers I'm talking about are the early 1980 Water cooled Main frame types. The RFI/EMIlab at Poughkeepsie was a huge fiberglass building. Nothing metal abovethe floor lever. The test guys therecould detect the number of cars driving down the road and tellhow many cylinders they were from theignition noise they picked up. Kind of like those movies ofthe sonar operators on a sub telling the Capitan
"they just opened a16oz can of white beans, I would know that signal anywhere".Don't know if they could tell theenginetype or not, but they were good atwhat they did. Ilearned a lot about extraneous noise from them. IE a star washer between theground strap lug and the frame of the computer or between the head of the screw and thelugcould be a difference of several hundred volts of noise on the covers before a failure.Attention to seemingly little details isreally need to combat noise. This is probably what weare seeing with this issue.Whose lack of attention remains to be determined. Maybe it isthe end user's problem. I'm sure the finger ispointing therenow.


The one wave length vs 1/4 wave length issue though kind of goes away with 2.4. It's more than just getting an overwhelming signal on your frequency, it has to be a signal the RX understands is coming from the TX it is to be listening to .At least my meager understanding of how it works leads me to think that. I would guess that if there was a strong enough signal spanning all ofthe band that would bring the RFIissue up front.

AJsToyz

Disclaimer: This is in no way any information that has been researched and or approved of or disapproved of by the poster. This information has no opinion of any way shared by the the poster. The information above was simply meant to be shared with the forum and hopefully has been made clear enough to understand. This information has been cut & pasted from the RCU Radio forum using the following link http://www.rcuniverse.com/forum/m_85...m.htm#10561804 post # 3633.

Sincerely

The bloody messenger.

Campgems

Is this written by AJsToyz, or Hitech??



You were doing good until you got to the part where your borther knew a guy who lived across the street from a guy whose cousin saw bigfoot..

Why throw crap in the game. Either you knoiw or you don't You apparently don't.

Don

BTerry

My Feedback: (8)

Don,

Read the link. There is no reason to shoot the messenger.

Tired Old Man

My Feedback: (1)

Curiouser and curiouser. I'll accept the memo came from Hitec. What I find interesting is that 42% ignition kills had in their earlier releases been failing periodically, and was happening long before RC Exl had put an ignition kill on the market. So I'm viewing this kind of like the pot calling the kettle black.

So did RC Exl copy an earlier design of the 42% product, and next, did 42% redesign their product for greater reliability? Interesting indeed.