Iflyit

My Feedback: (512)

I have a plane that needs tail-weight to balance, I was going to move the receiver battery pack back about 2 feet and I was wondering if the 2 foot length would hurt anything or give me any interference? I am using 2 digital servos and the rest are coreless and I have a 1500 mah pack.
I want to test fly this thing tomorrow

amcross

My Feedback: (2)

FLY, no, it shouldn't cuase you any problem, assuming it isn't tangled in with other leads, touching metal pushrods, etc.

Lynx

Any additional wire length adds to the possibility of interference. I don't know if anyone's ever tried, but putting a small ceramic capacitor (like the kind used on electric motors) Right where the connector for the battery goes into the receiver will almost completely kill the chances of any stray RF getting in from the long battery lead. Ferrite beads will probably work too but I think caps are better at killing interference. That and if you use large size electrolytic caps it'll actually help smooth out voltage drops from servo power hits. You only need the tiniest of ceramic caps to get the RF filtering effects.

strato911

Lynx - how about filtering capacitors placed near the servos after a long run? It should eliminate the RF (and crosstalk) picked up by the power leads there too. I haven't tried it, but was considering it since my farthest servo is 2.5 feet from the receiver in my current project. Either that, or a buffer circuit.

Iflyit

My Feedback: (512)

What do you mean by putting the cap near the connector? Do you mean in series with the positvie wire on the batt lead?

I flew it yesterday and it range checked fine, but i got 2 rudder servo hits in the air, I moved the antenna farthur away and will try again today.

strato911

No, the capacitor goes between the +ve and -ve wire (parallel). DC current doesn't pass through a capacitor, only the interference. Imagine the capacitor as a very tiny, very fast, rechargable battery of any voltage. It attempts to keep the voltage constant. If you do use electrolytic capacitors, they have a polarity, but small ceramic capacitors don't.

Lynx

Only some electrolytic are polarized they're easy to see because they're usually large for one and they have great big + and - signs on the leads =) If you're not sure find out before you use it. Like strato said they go between the hot wire (red) and ground (black) I've never heard anyone using caps for RF reduction on servo signals, I'm sure it'd work but even small caps will smooth out the square wave of the servo pulse, and that's going to alter the servo behavior and possible cause glitching. Then again it might not effect it at all, depends on the servo input signal electronics. As for the power I don't know how much a big cap would help but it will smooth out voltage spikes. As the technology matures super caps will become available at voltages that RC'ers can use and that can virtually eliminate voltage drops from large current hits because they can make HUGE caps that fit into very small spaces. They're just not easy to get, and usually work at only 1-3 volts so you have to run them in parallel and add extra circuitry to keep them from shorting, not real useful yet.

strato911

Lynx - LED's are pretty small and aren't labeled with a +

I was thinking of a filtering cap (0.1 microFarad) on the power wires of the servo. There shouldn't be an square wave there, but due to cross-talk and longer wires it is possible for the signal to propogate from the signal wire to the power wires. It would be so small, I could put it right inside the servo (unless there's one already there).

Lynx

Yeah but plugging in an LED backwards doesn't have a risk of exploding <snicker> Had a bad cap in a motherboard go once and take out the processor when it went. When the insulation goes there's a spark and if it can source any kind of current it vaporizes the electrolyte making it blow the casing right off the cap. Used to do that for fun hooking up 120 volt lines (fused of course) to 32volt caps. Man can those sucks jump.

bob_nj

My Feedback: (62)

I did what you are doing on my Morris Knife with great results. Don't know exactly how long the fuse is, but I ran the battery wire from the wing to under the stab. I did run the antenna perpendicular to that wire though out under the wing. If your antenna and batt wire are running parallel, maybe give that a try_bob

Whirley Bird

My Feedback: (1)

Shouldn't have any problems since the servos have voltage going to them also.
The important thing to remember is if your running the antenna inside the fuse you might consider running it outside the fuse.
All my antennas run from the top of the leading edge of the wing to the top of the tail.
Out in the open and in the clear

Iflyit

My Feedback: (512)

The antenna is not on the inside, its on the outside. I never run my antennas up to the rudder, just looks ugly and there is no need for it I ran it on the opposite site of the fuse and its OK now.

Forgues Research

My Feedback: (7)

It might be of interest, that I have been working with long leads and long power leads for quite some time now, and my experience shows that power leads are not the problem, but rather the signal wire is the culprit.

I have run power leads of up to 100 ft with no problem as long as the signal is not long, and for long signal wires, I replace this with Fiber Optics.

My servo battery is right along side of the ignition battery right under the engine tight against the ignition module. I wouldn't be able to do this if it weren't for Fiber optic.

It might also be of interest that I have finally achieved a total true redundent system using the Fiber Optic system. Not cheap to say the least, but very effective.
redundent