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-   -   RAM Beacon causes servo glitching; Help (http://www.rcuniverse.com/forum/rc-radios-transmitters-receivers-servos-gyros-157/11290222-ram-beacon-causes-servo-glitching%3B-help.html)

GoNavy 11-07-2012 07:13 PM

RAM Beacon causes servo glitching; Help
 
I am trying to solve an electrical problem and hope someone might have suggestions on how to isolate and fix this problem.

I installed a RAM products beacon, and when I turn it on, the nearby 1/4 scale rudder servo gets the jitters. Turn the beacon off and the jittering goes away.

The RAM beacon operates on 9 volts, with the power going to an electronic gadget which sends the current to the beacon on the tip of the rudder. The gadget causes the beacon light to vary in brightness, simulating a rotating beacon.

The aircraft has three batteries; a 9 volt just for the beacon (and landing lights), 4.8v for the receiver, and 6v for the servos (through a power board). The 4.8 v and 6 volt share a common ground. The 9 volt wiring is fully independent.

The three batteries are all in the nose. Power is supplied to the gadget from there on 38 inch leads (large aircraft). Receiver and power board are also on the ends of 38 inch leads. All three battery leads pass through a half inch diameter hold in a former and then they diverge to end about 4 inches from one another in the fuselage beneath the wing mounting.

The jittering servo is about 10 inches from the beacon gadget on a 12 inch lead from the power box. The receiver is about 4 inches from the gadget, and of course the antenna (72MHZ) runs from the receiver and aft within the fuselage, roughly on a parallel course but 5 inches away from the wiring from the gadget to the beacon.

I have also installed wing mounted landing lights. These are not powered yet. However, the 9v power for that will come from the same battery (no beacon effect) and is switched by an electronic relay (PicoSwitch by Dimension Engineering), located next to the gadget. This relay operates off the a spare channel (landing gear) via the receiver and that relay is powered at this time. (The literature for the switch states that it is a relay switch that offers full electrical isolation).

A second servo operates on the same channel as the rudder servo via a wye connector for nose gear control. It is in the nose, receiving power and signal from the power box on 38 inch leads. This servo does not have the jitters.

Servos are analog.

Troubleshooting so far:

1. Disconnected the relay from the receiver: no change

2. Disconnected the 9v battery in the nose, and temporarily connected the gadget to a 9v battery on 6 inch leads. Jittering was much worse.

That's all so far.






Unplug

Edwin 11-08-2012 07:23 PM

RE: RAM Beacon causes servo glitching; Help
 
What kind of servo is the rudder and what kind of servo extensions (are they tin pins or gold pins). I've had servo problems in the past that turned out to be the extension wire. I also had a servo that was jumpy with fresh charged batteries, think it was a JR Sport 125mg or something like that.
Edwin

GoNavy 11-08-2012 08:09 PM

RE: RAM Beacon causes servo glitching; Help
 
Servo is Hobbico CS-72; Extensions are Hitec, pins are not gold plated.

Servo is not jittery when beacon is not on.


A.T. 11-09-2012 12:56 AM

RE: RAM Beacon causes servo glitching; Help
 

Quote:

ORIGINAL: GoNavy<span style="font-size: smaller;"> I am trying to solve an electrical problem and hope someone might have suggestions on how to isolate and fix this problem.
I installed a RAM products beacon, and when I turn it on, the nearby 1/4 scale rudder servo gets the jitters. Turn the beacon off and the jittering goes away.
The RAM beacon operates on 9 volts, with the power going to an electronic gadget which sends the current to the beacon on the tip of the rudder. The gadget causes the beacon light to vary in brightness, simulating a rotating beacon.
The aircraft has three batteries; a 9 volt just for the beacon (and landing lights), 4.8v for the receiver, and 6v for the servos (through a power board). The 4.8 v and 6 volt share a common ground. The 9 volt wiring is fully independent.
The three batteries are all in the nose. Power is supplied to the gadget from there on 38 inch leads (large aircraft). Receiver and power board are also on the ends of 38 inch leads. All three battery leads pass through a half inch diameter hold in a former and then they diverge to end about 4 inches from one another in the fuselage beneath the wing mounting.
The jittering servo is about 10 inches from the beacon gadget on a 12 inch lead from the power box. The receiver is about 4 inches from the gadget, and of course the antenna (72MHZ) runs from the receiver and aft within the fuselage, roughly on a parallel course but 5 inches away from the wiring from the gadget to the beacon.
I have also installed wing mounted landing lights. These are not powered yet. However, the 9v power for that will come from the same battery (no beacon effect) and is switched by an electronic relay (PicoSwitch by Dimension Engineering), located next to the gadget. This relay operates off the a spare channel (landing gear) via the receiver and that relay is powered at this time. (The literature for the switch states that it is a relay switch that offers full electrical isolation).
A second servo operates on the same channel as the rudder servo via a wye connector for nose gear control. It is in the nose, receiving power and signal from the power box on 38 inch leads. This servo does not have the jiters.
Servos are analog.Troubleshooting so far:
1. Disconnected the relay from the receiver: no change
2. Disconnected the 9v battery in the nose, and temporarily connected the gadget to a 9v battery on 6 inch leads. Jittering was much worse.
That's all so far.Unplug</span>
Many possibilities, if answer not found below
"Glitches &amp; Jitter in Receiver, Servo &amp; ESC - Causes and Cures"
under
"Radio Systems, Accessories, Alterations and FAQ" at
Alan's Hobby, Model &amp; RC FAQ Web Links

Suggest best to contact RAMdirect in terms
Ram Radio Controlled Models Home Page quote
"For questions on products and info on specifics: Call Ralph at 847-740-8726
Ralph prefers to talk to you one-on-one."

Alan T.



GoNavy 11-09-2012 07:28 AM

RE: RAM Beacon causes servo glitching; Help
 
Thanks AT: I'm on it.

GoNavy 11-10-2012 09:32 AM

RE: RAM Beacon causes servo glitching; Help
 
Here's a report and my present thinking:

Upon further investigation, both servos on the rudder channel glitched; tho the jitters in the servo in the nose could not be heard, they could be felt by placing a finger on the arm. I eliminated the power board, but that did not change anything. I connected the two elevator servos to the receiver, and they glitched big time.

Ralph at RAM opined that the receiver "needed to be tuned" because it was "reading voltage variation" in the beacon circuit. He said that in the many years they produced the beacon this problem was reported only once before.
I substituted two other receivers with no change in the glitching. Leaving the antenna "coiled" at the receiver instead of laid out its length made no difference.

I tried relocating electronic items that could be relocated, 21 variations in total. In most cases this made no difference, but there were a few notable exceptions. 1 Moving the antenna from the rear fuselage and running it forward resulting in greater glitching. 2. Running the antenna at a right angle to the fuselage seemed to virtually eliminate the problem. 3. Disconnecting the battery from the nose, and connecting it to the gadget at mid fuselage resulted in increased glitching.

Perhaps the strangest was this: Adding two 12 inch extensions, one from the battery to the gadget, and one from the gadget to the existing leads to the beacon in the tail, eliminated the glitching. With this extra wiring I could put components back into the fuselage and there was no glitching unless I put my hand close to the gadget, within a half inch or less, whereupon slight glitching would start. Remove my hand and the glitching stopped.

I called Airtronics and learned they no longer service their 72 MHZ equipment. They referred me to the fine folks at Radio South in Georgia who gave me of their time and advice. They opined that the receivers did not need to be tuned. They felt that the EMI radiating from the beacon wiring had a harmonic that was being read by the receiver; that I might try, as an experiment, a Hitec receiver that synthesized frequencies, and alternately said that swaping the 72 MHZ system for 2.4 GHZ would solve the problem. They felt the twisted wire pairs I had used for the beacon system wires were insufficient to reduce the EMI and suggested shielded cabling would probably do the trick.

If I eliminate the dimming feature, run a flat 9 volts to the beacon, there is no glitching. That is what I probably will do; Replacing the twisted two wires with shielded wire, or adding shielding around the twisted pair, at this late stage, would be difficult, probably not possible in places (i.e., the 18 inch long vertical run in the leading edge of the fin).

TFF 11-10-2012 09:57 AM

RE: RAM Beacon causes servo glitching; Help
 
Strobes on real airplanes can case noise in their radios too. you might try grounding the 9v with the others. You also might want to twist the servo wires or get braided extensions. It is also best to keep the unit as far away from wires and radio parts. The box is something like a gas engine ignition so similar solutions are what you need to look at. Ferrite beads might help too.

Edwin 11-10-2012 10:11 AM

RE: RAM Beacon causes servo glitching; Help
 
Maybe try some ferrite chokes too. I would be curious if that helped any. In my job we depend on shielded cable quite a bit to keep clean digital signals from solenoids.
Edwin

GoNavy 11-10-2012 12:39 PM

RE: RAM Beacon causes servo glitching; Help
 
Edwin:

I wondered about those. I surfed the web a bit on the subject.

It seemed like these needed to be selected for the type or? frequency of the EMI, is that the case? How does a guy know when he has the right ferrite choke?

Where would you put these? On the beacon circuit wires? On the lines from the receiver to the servos and/or to the power board? On the lines from the power board to servos?

I have found some possible shielding: I could replace the 38 inches of two wire twisted from the nose to center of the fuselage with something like this:http://www.ebay.com/itm/priced-per-f...item51a00c57be

I could probably snake this around the run from center fuselage to tail: http://www.ebay.com/itm/Coaxial-Cabl...item3359a06dc6

But, it would be very difficult to do anything with the length of wire within the fin, so I worry about whether or not these would solve the problem.

I found a 9v flashing system listed at Radical RC and I have sent Dave Thacker an email in hope that unit might solve the problem:http://www.radicalrc.com/category/Lighting-System-267 (last item on the page, High Sky strobe).

In 22 years in rc I have never had this problem before.

GoNavy 11-10-2012 12:45 PM

RE: RAM Beacon causes servo glitching; Help
 
TFF:

I'll try grounding the 9v with the ground for the receiver and servos.

I was surfing for information about grounding. This plane has a significant main landing gear consisting of 1/4 inch diameter steel rod and a large 3/16 inch thick aluminum backer. Query: Would it improve this to connect all the systems to the metal of the landing gear?

GoNavy 11-10-2012 01:15 PM

RE: RAM Beacon causes servo glitching; Help
 
TFF:

Grounding the 9v beacon system with the radio reduced the glitching...hard to say how much, maybe half as much.

Then grounding everything to the landing gear ... it was Katy bar the door, glitching like never before. So much for that idea.

I guess what we have is an EM field generated by any wiring in the 9v system, and that only causes a problem because, in the beacon mode, the field is varying, regularly, in strength, generating somethine akin to the EM field of a running electrical motor?
The "frequency" of bright to dim back to bright is about once every three seconds.

The reason the glitching is greater with the antenna aligned with the fuselage c/l is that it is then roughly parallel to the 9v wiring, and when I had the antenna at right angles, it picked up very little of the em field?

Edwin 11-10-2012 04:50 PM

RE: RAM Beacon causes servo glitching; Help
 
Ground is the negative side of the batteries. Grounding to the landing gear doesnt do you any good. As for the chokes, somebody someplace somewhere sells chokes for RC. I finally found the key words to use are "rc ferrite ring" for a google search. Lots of reading from various other forums that should be helpful. I dont really recall where they would be placed, source or destination. That would depend on the source of the noise you're trying to suppress which in this case you know is the beacon system. The RC chokes may or may not be different for the beacon since it will be a different kind of noise from 72mhz. But experimenting would probably prove useful.
Edwin

How about zigzaging the antenna down the fuse instead of straight line.

A.T. 11-10-2012 06:02 PM

RE: RAM Beacon causes servo glitching; Help
 
1 Attachment(s)

Quote:

ORIGINAL: GoNavy TFF:<span style="font-size: smaller;"> I'll try grounding the 9v with the ground for the receiver and servos.
I was surfing for information about grounding. This plane has a significant main landing gear consisting of 1/4 inch diameter steel rod and a large 3/16 inch thick aluminum backer. Query: Would it improve this to connect all the systems to the metal of the landing gear?</span>
Keep all antenna and leads away from metal pushrods, LG etc.
Earth (ground) RCsystemy via the battery negative only, but keep beacons etc well
isolated from RCsystem, using opto switches or otherwise as in information available post #4.
Ferrite rings (aka "chokes") available from Jamara and Multiplex are as attached

Alan T.
Alan's Hobby, Model &amp; RC FAQ Web Links

GoNavy 11-11-2012 09:14 AM

RE: RAM Beacon causes servo glitching; Help
 
Per one of the articles Alan refers to, I tried:

-shielding the receiver in aluminum foil. No improvement

-shielding the beacon gadget in aluminum foil. No improvement

-shielding with aluminum foil, the beacon wiring in the fuselage opening where it was accessable -significant reduction in glitching. HOWEVER
as I walked around the work table to try other things, I noticed that where my body was in relation to the plane significantly affected the glitching; If I stood in the left front quadrant, even though I was more than two feet from the fuselage, the glitching became violent. My body must be acting as some sort of reflector?????? This EMI that plagues me must be very strong.

Another technique discussed in the article, and mentioned by Dave Thacker of Radical Rc, is connecting a capacitor between the positive and negative wires from the beacon gadget, even perhaps, additional ones along the wires. It is said the capacitor does not permit the transfer of the low voltage current, but higher frequency EMI passes through the capacitor and is thereby cancelled (shorted out?). Now the question is, what capacitance to try. I haven't seen guidance on that yet.

GoNavy 11-11-2012 09:20 AM

RE: RAM Beacon causes servo glitching; Help
 
Oh, I should also mention something else: The long extension to the servo in the nose is a Hitec "boostered" extension. I understand the little circuitry there boosts the signal voltage to the servo if it is weak. I thought these were also able to remove unwanted interference, but I haven't been able to confirm that.

Edwin 11-11-2012 11:28 AM

RE: RAM Beacon causes servo glitching; Help
 
The cap is an old time honored method for noise reduction. But for the caps to really do their job, they have to be tuned to the noise you're trying to filter. But you can try some ceramic .01, .1, and .001 uf. Those are some standard values we used to use a lot to get a wider band of filtering when we were just shooting in the dark. I've never been comfortable with amplified extension cables. If you get a glitch, it doesnt necessarily filter it, sometimes it amplifies it. I've also seen several of them fail, along with reversing Y's. Just my experience, others may vary. Is the antenna in the fuse? If so, maybe run it outside along the bottom of the fuse. Probably a combination of caps, ferrite cores that AT showed, antenna moving and some sheilding. Seems like it might be time to consider an upgrade to 2.4.
Edwin

GoNavy 11-12-2012 05:02 PM

RE: RAM Beacon causes servo glitching; Help
 
Time to do the dance of joy.

I was taking an old radio apart in hopes of finding an appropriate capacitor (we are 50 miles from nearest Radio Shack) when I noticed a toroid ferrite on the antenna ground wire.

It seems to solve the problem. I used a spare extension to wrap it, and inserted it in the beacon circuit. Amazing.

Now I'll try putting things back in place in the fuselage, but at this point things are looking good. All thanks to one little ferrite donut.

A.T. 11-12-2012 06:50 PM

RE: RAM Beacon causes servo glitching; Help
 
1 Attachment(s)

Quote:

ORIGINAL: GoNavy<span style="font-size: smaller;"> Oh, I should also mention something else: The long extension to the servo in the nose is a Hitec "boostered" extension.
I understand the little circuitry there boosts the signal voltage to the servo if it is weak. I thought these were also able to remove unwanted interference, but I haven't been able to confirm that.</span>
Boosted Servo "Y" and Extension Leads Full details and diagrams at Servo City, extract:
"<span style="font-family: 'Arial Baltic', sans-serif;">A buffer-booster extension is basically a servo signal amplifier.
</span><span style="font-family: 'Arial Baltic', sans-serif;"><span style="font-family: 'Arial Baltic', sans-serif;">. Whenever you are running a servo over a considerable distance (24"+) from the receiver or you are running
two or more servos off of the same channel. Each servo absorbs a little of the servo control signal coming out of the receiver.
As more servos are added, the signal to each servo is weakened. The effect of multiple servos (as in two or more servos on a Y-harness)
add up and therfore may cause jittering or lack of constant control.
</span>It boosts the signal from the receiver so that the servo receives a cleaner, clearer, more powerful signal.</span>
<span style="font-family: 'Arial Baltic', sans-serif;">. Some servos utilize circuits that set an input threshold level at a certain fraction of the line voltage so that any signal below
the threshold will be rejected as random noise. Unfortunately, the threshold is normally about 50% of the power supply voltage.
This works fine for 4.8V batteries (threshold is 2.4V) or partially discharged 6V batteries (threshold is 3V) but a fully charged 6V battery
peaks out at 7.2V (threshold of 3.6V) or multiple servos on a 6V system threshold 3V but multiple servos load the receiver output to
below 3V which leads to intermittent or jittery operation.
A buffer-booster will increase the line signal voltage back up to your original power supply input levels.</span>"

Beware of Miracle Wye The connectors maybe Hitec/JR compatible.
The Miracle wyes electronics or design parameters must be designed to be used with Futaba/Hitec RX equipment or
whatever you specifically use.
The brand to brand requirements are different when considering the use of amplified wyes or extensions which causes
problems on 6v.
All receivers have a voltage regulator onboard to protect their ICs.
The output level of the control signal going to the servo is not the same from JR to Futaba/Hitec.
JR receivers output the full battery voltage on the servo signal line. Futaba/Hitec receivers output about 3.3V to the servo
on the signal line, with some recent Futaba signal now lower. All receivers pass the full input voltage to the servo power lead.
Perhaps some older Hitec units (been discontinued for a couple of years or so) maystill beavailable LHS. <span style="FONT-SIZE: smaller">use in my large J3.
</span>

Alan T.
Alan's Hobby, Model &amp; RC FAQ Web Links


Edwin 11-12-2012 06:50 PM

RE: RAM Beacon causes servo glitching; Help
 
Voodoo black magic. :D
Edwin

dirtybird 11-12-2012 08:17 PM

RE: RAM Beacon causes servo glitching; Help
 
What is a Ram Beacon?

A.T. 11-12-2012 09:37 PM

RE: RAM Beacon causes servo glitching; Help
 
Quote:

ORIGINAL: dirtybird What is a Ram Beacon?
Ram produce many different accesspories for RCModellers, initially Fog horn and other boat sound and light effect boards.

As in post #4 above - <u><font color="#00265e">Ram Radio Controlled Models Home Page</font></u>



Alan T.

GoNavy 11-13-2012 02:15 AM

RE: RAM Beacon causes servo glitching; Help
 

Quote:

ORIGINAL: Edwin

Voodoo black magic. :D
Edwin
Igor like voodoo black magic!


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