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Author Topic: SEGREGATION OF WIRING  (Read 3122 times)

BarryM

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SEGREGATION OF WIRING
« on: April 25, 2007, 02:39:42 PM »

I try to follow the rule of running power wiring up one side of my models with servo cables up the other and thereby minimise the possibility of interference. Howver, if servo wiring is bunched too closely together, can this itself lead to a signal to one servo interfering with a signal to another? Would it be better to seperate servo cables on a spider arrangement if only slightly - or is the radiation involved too small to matter?

Thanks for all replies.

Barry M
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Shipmate60

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Re: SEGREGATION OF WIRING
« Reply #1 on: April 25, 2007, 03:13:00 PM »

Barry,
In theory yes, but in practice no.

Bob
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wombat

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Re: SEGREGATION OF WIRING
« Reply #2 on: April 25, 2007, 06:48:54 PM »

You can get coupling between the servo cables which can lead to problems depending on the hardware of the servo.
THe problem is the capacitive coupling between the two cables. Best thing to do is to lay the cables side by side rather than one on top of the other.

I would think though, you will only see any effect if the runs are quite long - like a couple of feet.

Wom

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BarryM

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Re: SEGREGATION OF WIRING
« Reply #3 on: April 26, 2007, 06:41:07 PM »

Thanks Lads - My current model has some rather long servo cables. I'll be a bit more careful when routing them.

Barry M
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Doc

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Re: SEGREGATION OF WIRING
« Reply #4 on: April 27, 2007, 03:06:44 PM »

And another solution is to 'twist' the cable of one or more (if more than one) of the servos.  This, in effect, cancels out any interference between cables because what is transfered during one 'twist' is then canceled on the next 'twist'.  Works with almost any multi-conductor cable ~if~ the interference isn't very 'large'.  Interference between servo cables isn't exactly very high on the list of things to watch for.  Possible, but not too likely.
 - 'Doc

'Twisting those cable 'together', so that they all go the same direction, parallel to each other sort of defeats the whole purpose.  There really are reasons not to have a neat and tidy installation.  Ha! And you thought I was just messy!  well... sometimes I am, but it works.
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Peterm

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Re: SEGREGATION OF WIRING
« Reply #5 on: April 27, 2007, 04:13:12 PM »

Doc, you are right, of course.   Nice to hear from you again, I thought you were hibernating.   Pete M
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BarryM

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Re: SEGREGATION OF WIRING
« Reply #6 on: April 27, 2007, 05:37:37 PM »

Doc,

Sorry but I understood (I thought) your first paragraph and then your second paragraph confused me.

Do I take it that if I put a twist in a servo cable running parallel to another similarly twisted (but seperate) cable then that cancels interference but two or more servo cables twisted together in a bunch do not have the same effect?

This is obviously a three beer problem. Doh....

Barry M
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Doc

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Re: SEGREGATION OF WIRING
« Reply #7 on: April 28, 2007, 09:37:23 AM »

Barry,
It may be a three beer problem, but usually it's because I just say something wrong (I'll take the beer though!). 
If wires parallel each other they tend to affect each other more than if they were not parallel.  Altering that 'parallelness'(?), and how close they are to each other, changes how much they can affect each other.  Increasing it means more chance, decreasing it means less chance.  So, if you twist one cable so that it changes it's physical relationship to the 'other' cable, that can be good.  Running them 90 degrees from each other produces the most change.  (And if you figure out how to do that, you are going to wire all of my boats!)  Has to do with mutual inductance and capacitance (and if you think you've had a three beer experience before, get me talking about that!).  Ain't electricity fun?
 - 'Doc
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BarryM

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Re: SEGREGATION OF WIRING
« Reply #8 on: April 28, 2007, 10:08:55 AM »

Thanks again Doc - you seem to have become my personal Guru on this and other subjects.  Tell you what - you have that beer and I'll pay for three at this end to compensate.  ;D

Cheers!  :D
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catengineman

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Re: SEGREGATION OF WIRING
« Reply #9 on: April 28, 2007, 12:00:51 PM »

Hi, Doc

Can I ask you a question regarding this subject.  I and here is where I may be wrong thought that 'screened' cables reduced the effect talked about? which is why I ran my steering servo leads in this form.
Though I now have rerun them trying to sort a problem out which turned out to be the receiver unit (another story) and now I do see small glitch twitching on the steering servos (I'm living with it at the moment)
Should I refit the screened cables to cure this ?

Richard,
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Doc

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Re: SEGREGATION OF WIRING
« Reply #10 on: April 29, 2007, 12:49:53 PM »

Richard,
I certainly can't say that using a 'shielded' cable wouldn't help!  I just have no idea if it would be worth the trouble.  'Shielding' or 'screening' does work.  The 'catch' is that the whole thing ought to be shielded/screened, or interference can 'leak' in somewhere else.  (Sort of like running the water line and the sewer line close to each other.  Not really a problem if both systems are sealed/shielded/screened from each other.  I don't wanna talk about the alternative.)
If you can't easily shield/screen the cables, how about shielding/screening the sources of the interference?  Sometimes that's easier, sometimes not.  If it produces a spark, electrical or magnetic field, it can produce interference/glitches.  The 'trick' is to keep those sparks/fields where they are supposed to be and not where they aren't supposed to be.
 - 'Doc

Technical terms.
Capacitors: 'Cow-pastures' cuz they're "sh****" little things.

Interference: Something in the wrong place at the wrong time.

Torroids:  Lumps of some graphite looking stuff that is to interference like Kryptonite is to Superman.

Conduit:  "Can do it", but not all the time.

It's the little things that get'cha!

The rest of that electronic technical stuff is secret.

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catengineman

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Re: SEGREGATION OF WIRING
« Reply #11 on: April 29, 2007, 01:36:00 PM »


Technical terms.
Capacitors: 'Cow-pastures' cuz they're "sh****" little things.

Interference: Something in the wrong place at the wrong time.

Torroids:  Lumps of some graphite looking stuff that is to interference like Kryptonite is to Superman.

Conduit:  "Can do it", but not all the time.

It's the little things that get'cha!

The rest of that electronic technical stuff is secret.



Like them alot!
 So is that why hertz is called that co's it HURTS when you come in contact with it ;D

richard,
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catengineman

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Re: SEGREGATION OF WIRING
« Reply #12 on: April 29, 2007, 01:47:11 PM »

Just thought I had better say I desoldered my original servo wires and fitted screened cables because they would run very close to the motors and also past the three batteries then through serial port plugs and sockets before entering into the accommodation where I originally sited the receiver (so I would not have to cut / alter the aerial length. [Phah what did I know]

I am now with normal servo wires and the receiver is fixed to the top of one battery, aerial just drooped from outside the accommodation.

The first fix was the neatest the second is where I have ended up after a long problem solving trip and all because the RECEIVER had a bad joint at the ARIAL

Richard,
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portside II

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Re: SEGREGATION OF WIRING
« Reply #13 on: April 29, 2007, 04:13:36 PM »

On the subject of wiring ,i had Brakengarth out on the pond the other day after fitting a bilge pump (the stern sits down now after fitting some lead ballast and the water washes over the work deck through the wash-boards into the bilge through the hatch).
All was well  she was pushing the new crane /dumb barge around and then all went quiet  and the jjc sound made a noise like the engine had water in the fuel .
Damn i thought there goes the board , it was later that i began having problems keeping control of her like someone else was on the same chanell .
It was'nt until i did a process of elimination ,crystal check etc ,and finaly unpluging the sound unit that i realised the reciever battery was flat.
So it was out with the old and in with a fresh one connect everything back up and Yes Yes the cat woke and started growling again huray!!
Oh and to go with the subject of segregation of wires mine looks like spagetti junction after a 4.8 on the richter scale and it still works, It was just a flat battery.

daz
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DickyD

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Re: SEGREGATION OF WIRING
« Reply #14 on: April 29, 2007, 04:23:35 PM »

I must be lucky, haven't a clue about any of this. Chucked it all in and it works fine.

Richard ;)
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catengineman

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Re: SEGREGATION OF WIRING
« Reply #15 on: April 29, 2007, 07:22:35 PM »

Yes I have had NO problems with any of the 'capt jack's' boats all have had the same care as my own and there is where the similarity ends.
kiss technology has a lot to say for itself!

Then there is MY tug over enthusiastic would be kind of 1 answer.

channel 1 = Stbd steering servo
channel 2 = Stbd drive motor ESC
channel 3 = Port drive motor ESC
channel 4 = Port steering servo
channel 5 = Bow thrust ESC
channel 6 = Anchor winch (converted servo) + [change over switch for Gog winch unfinished]
channel 7 = Light control and radar control relay switcher
channel 8 = Fire Monitor / cooling water pump via servo switcher
                 yet to finish installation stern winch and bilge pump.

So you may be able to see where some of the small problems came from though if I was honest and said that it could have been my fault that the aerial became detached from the board inside the receiver which gave me so much trouble then it could be said that I brought all this on myself.
And to top it all I did have A VERY NEAT setup but now it's like a plate of spag :'(

I have even got to squeeze into the tug one multi-prop decoder so that I can finish all the bits and bobs off, it may be a big tug but there just ain't that much room left, if I throw out one battery I sacrifice the time I can play (3.75 hours on Saturday on my local pond) only stopped due to spanner in the works wanting to go "home" plus one battery is 6volt for rec/bow thrust/lights and bow winch.

I need a BIGGER hull.

Richard,

Richard,
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malcolmfrary

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Re: SEGREGATION OF WIRING
« Reply #16 on: April 30, 2007, 01:26:07 PM »

Doc forgot to mention the magic smoke that causes all electric thingys to work, and must at all times be retained within said thingys.
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catengineman

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Re: SEGREGATION OF WIRING
« Reply #17 on: May 01, 2007, 12:09:19 AM »

Where can I get some new smoke for me electric thingy's ?

Mine seems to be running out

Is it like AC units and need redoing every now and then?

Richard,
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malcolmfrary

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Re: SEGREGATION OF WIRING
« Reply #18 on: May 01, 2007, 10:45:18 AM »

The magic smoke is "use once only".  Once it has gained its freedom, a replacement thingy is normally needed.
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catengineman

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Re: SEGREGATION OF WIRING
« Reply #19 on: May 01, 2007, 02:12:51 PM »

Hey I must be lucky!!!!

only some bits of my electrical thingys work and some bit dont  = only some smoke stuff escaped ;D ;D

Richard,
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