sthill

So, I just finished a DLE20 upgrade for my Aeroworks Extra 300. I was running a 5 cell 6v 2000mah NIMH battery pack on the receiver and when I added the DLE20 I added a 4 cell 4.8v 2000mah NIMH for the ignition. All seemed well on the bench with batteries that only had a partial charge. Today I charged up the packs and took it outside for the first run but noticed that the LED on the RCEXL Opto Kill Switch would go on and then shut off and reboot over and over. I verified the “reboot� behavior with the RCEXL tach that is installed. The funny thing is when I would move all of the sticks over and over the ignition would stay on while the servos moved (I assume that this is because the current draw of the servos brought the two systems close enough together in voltage)! I tried a bunch of different approaches but the only thing that seemed to fix the problem was to install a 4.8v receiver pack. So my question is this?

Does anyone know if it is a requirement for the RCEXL Opto Kill switch for both the ignition and the receiver pack to be the same voltage?

I didn’t try a 6v receiver and a 6v ignition but I have a gut feeling it will work too. If the receiver / ignition system were truly optically isolated I’m not sure why the voltage difference would matter, but it seems like it does.

FYI, I know there were issues with these kill switches and some specific Futaba radios. I am running an Airtronics 2.4ghz 8 channel receiver and set the end points for the switch endpoints that controls the rcexl opto kill switch to the extremes.

Thanks in advance for the help!

dant-RCU

My Feedback: (3)

I am running Life Rx pack (2) and a 4.8 V NiMH pack for the RxEL Opto Kill Sw using a Futaba 12Z. I have the ATV set to 100% on channel 7 (kill sw). Works like
a charm and does not exihibit any of the symptoms you are having.

I have the identical setup on two different models.

Dan

a1pcfixer

My Feedback: (7)

It's been noted by Jody several times recently that the DLE20 ign prefers 4.8 -6.0 volts, not anything higher.
Keep it below 6.0 volts and go fly!

ahicks

My Feedback: (2)

I'm confused. Did you mean to say you're running the 5 cell to power the receiver?

Also, if you're running relatively high output digital servos (or if you have smaller with one that's possibly stalling?), you're likely exceeding the capacity of the 5 cell NiMh to keep up. Just found that out recently myself. The AA cell NiMh chemistry is really wimpy when it comes to supplying amperage compared to any other battery chemistry type - and nobody is saying anything about that when selling them - so that fact is not as widely know as it should be...

To use what I had laying around, I ended up using 2 5 cell NiMh packs to power the receiver, and used a dropping diode to supply power from that to the ignition (switch). That works great.

sthill

Sorry for the mistake on the original post. I am running a 5 cell 6v on the receiver and a 4 cell 4.8v on the ignition. I took the rcxel opto kill out of the loop and ran the battery/switch directly to the ignition and I don't get the "reboots" anymore (tach stays on and doesn't reset). What is odd is that the ignition isn't resetting when I move the sticks constantly so I don't think I am getting a low voltage condition. I just wonder if I am getting a high voltage condition where it will reset when nothing else is happening. Either that or the rcexl doesn't like my airtronics receiver. Not sure what to do next. I'm thinking of ditching the opto kill for a differnt brand. Any suggestions?

Thanks for the assistance.

skip1320

Could be a hidden/unknown mix on your opto kill port.

NJRCFLYER2

My Feedback: (42)

The Tech-Aero Ultra IBEC will solve this for you.

bgw45

My Feedback: (1)

Sthill, your set-up is similar to mine. I am flying two gassers with the RCXL kill switches and they work great. You could have a bad opti switch. It happens.

sthill

All,

Thanks for the help. I believe it is a receiver compatibility problem with the RCEXL kill switch. I tried the same configuration with a Spektrum receiver and a different Airtronics receiver model and it works fine. I am posting to Airtronics support to see if they have any ideas.

pilotpete2

One more item to check. Your RC Excell Opto kill may just be jumpered to operate as an IBEC (they can do that). Simple test, disconnect the ignition battery and test the system. If the ignition still operates without the ignition battery, that's the problem, you may have a 6V battery in parallel with a 4.8V[]
Pete

raptureboy

I'm using the exact same setup with the airtronics radio and recv and I had a problem only because I hooked up the plugs incorrectly. Dbl ck your hook up against the wiring diagram that came with the kill switch. I have mine hooked up to the gear channel

Planeclothes

My Feedback: (1)

I am a bit concerned about this, since I have the same setup, Airtronics RDS8000, 92824 8 channel receiver(s), 6v 2000 mAh nimh receiver pack and 4.8v 1400 mAh nimh IM pack. I always try to use the least number of components on RC setups, the more gadgets you have, the more chances that anything can go wrong along the way. So for my gassers I only used analog (mechanical) kill switches but a couple of recent incidents made me change my mind and decided to buy 2 RCEXL kill switches. One of them was defective when it arrived and was returned (I am still waiting for a new one). The other one seemed to be fine (on the ground) but after I took off, at no more than 15 ft high, the engine suddenly stopped. At first I thought it an engine issue, but it is kind of odd because this engine (JC 28) have had some issues at low idle but had never quit at full throttle. On the other hand, I talked to a fellow club member at the field and he says he uses these switches on all his gassers with no issues whatsoever, but he has a different radio system.

tdriver

interesting....are there any instructions to do this?

jedijody

My Feedback: (1)

Yes, use a magnifying glass to view the picture and instructions on how to convert the Rcexl ignition switch to an IBEC on the bottom of the instruction sheet that comes with the switch.

sthill

You can tell if the optical kill is cutting off the ignition if the light blinks but, IMHO, the best way to see this behavior is to install an rcexl tach, the tach (which plugs into the ignition) will show the reboot with all 9999’s and a code when the reboot happens. IT makes the reboot much easier to see. I would charge up the batteries and leave it sit with the ignition RX and ignition on for 5 minutes or so on the bench. Mine can take a few minutes to start blinking but when it does it really starts going until I shut off the unit and start again. I’ve noticed that newly charged batteries show this problem much more quickly than batteries that have sat around for a few days.

I’m positive everything is wired correctly because I swapped out the Airtronics 92824 RX with a Spektrum RX and it was fine. I also tried the exact same Airtronics radio, settings, etc. with an RX500 and could not get the optical kill to “reboot�. I even tried a second 92824 RX to see if it was an issue specific to the original receiver, it wasn’t.

I’m currently struggling with the decision to either buy a different brand optical kill or buying a different model receiver (RX700 for example). Honestly, I’m not sure which one I will have better luck with. I just want this setup to work reliably!

(Oh, FYI. I did try unplugging the ignition battery from the optical kill and the ignition wouldn’t start so I am confident that the optical kills isn’t running as an IBEC.)

tdriver

the manuals i found have a note in red color: "the kill switch not including BEC function"

do you have a link to take a look?

Antique

My Feedback: (4)

Don,t engines die when the throttle is closed? Or has Walbro changed something...My xmtr has a button that shuts the throttle all the way when pushed....2000 or so idle, push the button, it dies....What could be easier and cheaper ?

Planeclothes

My Feedback: (1)

It is easier and cheaper as long as the throttle servo is working. The idea of having an Opto kill switch is to kill the engine from the tx when there is servo failure or a loose throttle link, etc. It will also kill the engine when there is no signal coming into the rx.

Lightning Fan

My Feedback: (17)

I just started playing with one of these things, and I think I know what may be going on.
I'm using a Futaba 14 channel 6014 RX.  The kill works OK on channels 1 and 2 but will not work on any other channel.  I need to verify this with a bit more testing, but while rummaging in my Futaba literature, came across the product notice for the Rx which clearly states that in order to improve speed, the output voltages had to be reduced to around 3V.
It could be that the reason I see channels one and two work, is that they have slightly higher output signal amplitudes ... enough to trigger.
Now before you jump on me and tell me to check the programming ... I've checked that when I operate the other channels, a test servo moves, so I'm definately operating the channel I'm connected to, and I also drove the endpoints all the way to 140%.  I doubt that it is the transmitter or wiring here.
I'd also note the intermittent behaviors described above ... seems like my explanation of being "on the edge of the threshold voltage" might apply there as well.  I'll be spending the next hour or so combing RCU and other forums for other folks that may have encountered this.
If the RCEXL opto switch needs to see higher voltages to detect the pulse, I think ... I'm screwed.
The product notice kindly noted that I could fix this by buying aftermarket powerbox units, which they listed.  I do not want to put MORE stuff that might fail in line just so these switches work. 
Maybe it will work with lower channel count RX's ... but my confidence is shaken.  I was considering using these things on a P-38 because I am nervous about a throttle servo on one side dying at 30% power which would be awkward since I would not be able to fly on that for long, but I can't land that way either.  The probability of this happening is very low I've never had such a thing happen in 40 years of flying.  But, I thought I'd try this second thoughts now.
I believe I have two brand new RCEXL units that will be going to the next swap meet - I hope I can figure this out.

Lightning Fan

My Feedback: (17)

One other thing.
I've read with great interest the periodic discussion of whether kill switches are good or bad.  I have not used one in the past been flying gas for about four years now, with no issue.
I understand everyone's arguments, and respect each person's opinion about the use of these devices.  I think that this thread is about a technical compatability problem of the RCEXL kill switch and some newer RX's, and specifically the RX voltage outputs (and supply, although I doubt that is a factor).
It is not necessary to retype all the "you need one!  for safety!!" and "no you don't, think about the risk analysis, and set up your equipment correctly!".  I've read a lot of those threads, so save yourself the effort.  It would be great if we could confine this discussion to the performance of this device.

Lightning Fan

My Feedback: (17)

Darn.
It didn't take too long to find it.  Lesson learned ... again.

http://www.rcuniverse.com/forum/m_96...tm.htm#9646400

Tired Old Man

My Feedback: (1)

Use better servos? In 40 years of modeling I have not once experienced the troubles with a throttle servo so many seem terrified of.

Lemmings[:@]

Has the 8 ch. receiver ever been in a plane that crashed? If so, was it checked by an expert technician before being used again? Airtronics makes good stuff and it's rare to obtain a defective part from new inventory.

jedijody

My Feedback: (1)

I fly Airtronics SD10-G, I have three 50cc planes with 8 ch, 92824 Rx's in them and one 100cc plane with the 10 ch Rx. All have optical ignition switches plugged into ch 5. Three of the four are Rcexl switches, the other is a 42% Products switch, all work flawlessly. Look at this test done at the Rcexl factory, http://www.rccdi.com/news/Accessories/10.html

Not sure what the problem might be, these switches are extremely reliable.

Lightning Fan

My Feedback: (17)

Nice video.  It adds the final explanation.
After looking at the video, I was dumbfounded and went out to the shop again.  I plugged the setup back into the 6014 ... same story, no operation.  I switched to a $30 HobbyKing FASST 8 ch Rx, and plugged into exactly the same channels.  The switch worked fine.
Video no question, it works.
My test  no question, it doesn't work on the 6014, unless I use channels 1 and 2.  It works on another type of RX.

Man, I looked at that video a lot ... and found it.  He is using a 6014HS RX.  I have a 6014FS.

And then I found the message below.  Clearly, the threshold voltage for the switch is in excess of the 6014FS, which was probably corrected in the 6014HS.  Now, it looks like I have a receiver that I have no confidence in.  Pretty pissed off about that, but I'm glad I found out about it prior to flying it more - I have flown this RX with Hitec servos before with no issues.  Only this switch has not worked, but I do not think that the switch can be faulted.  The RX does not meet commonly accepted signal voltage requirements, as evidenced by the upgrade to the HS.

Reply #6 - Mar 26^th, 2008 at 6:05pm

Doug Williams   Offline GSWAM Club Member GSWAM Forum Member Bedford Posts: 43  <input name="del6" type="checkbox" value="6" class="windowbg" style="BORDER-BOTTOM: 0px; BORDER-LEFT: 0px; DISPLAY: none; VISIBILITY: hidden; BORDER-TOP: 0px; BORDER-RIGHT: 0px"/> I bought an  oscilloscope from Dave Horton and we measured the white wire signal voltage on some of my receivers last night. The Speltrum AR9100 and JR R921 2.4GHz receivers checked 3.277 to 3.341 volts which is good. The Futaba R5014DPS 72MHz receiver checked 3.020 to 3.050 volts which just makes it to the required 3.0-5.0 volts required for Hitec servos. My new Futaba R6014FS 2.4GHz receiver checked 2.980 to 3.020 volts on channels 1 and 2 respectively. But the voltage dropped down to 2.666 to 2.698 volts on channels 3 through 12. That means a Smart-Fly or other power expander is definitely required when using Hitec 5955 servos with this receiver. We also checked two of the Smart-Fly 14MZ power expanders and found the white signal wire was boosted to 4.880 to 5.010 volts when connected to either one of the Futaba receivers. Doug Williams

sthill

All,
Thanks for the help. I’ve tried just about everything I can think of to get the RCEXL switch to work with my 92824 RX including: changing batteries (4.8v and 6v), taking the mechanical switch out of the loop, unplugging all of the other servos on the RX, changing channels, changing endpoints on the channels, etc. I’m pretty sure my configuration isn’t to blame as I have tried other Airtronics and Spektrum receivers and they seem to work with the Opto but neither of my 92824 receivers work. I guess I could have gotten a bad optical kill but it just isn’t worth wasting my time on anymore.

So gave a Tech-Aero Ultra IBEC a try and am very happy with it. I took it out and ran it for almost 30 minutes this weekend and not a hiccup! Since this is a smaller model (20cc) I can save a battery and get the plane to balance much better. For $55 I think this product is a good deal as it isn’t much more than an ignition battery + optical kill. I think the best thing I can say about this product is that it just works: simple, clean, easy and light.

Regards,
Steve