Will long wire lengths pose issues?

Other Hardware General Electronics
1

Hello all!

I've found my way into the world of Arduino because I decided to build myself a skeeball game. I have made it a goal to build an electronic scoreboard for the game. I thought this was a tall task, as I had no programming experience, or experience with wiring as it relates to computers and circuit boards. However, I've been in the world of hobby class RC for many years, and do have some basic experience with wiring low voltage components, soldering, etc.

I got a huge shortcut when I found an Instructable (or 3) where someone built a skeeball game and gave specs on the build in detail, including the components, wiring, and code for the marquee. I've used this forum, an "Arduino for Dummies" book, and a relative who is a programmer to work out most of the code so I can actually understand what's going on in it. I believe I have most everything sorted out, but we'll see when it's time to put my money where my mouth is.

The most recent question I have developed is, will long wires pose any issues for me? The servo for the ball drop "flaps" and the reset button will need lengths of wire around 10-12 feet, most likely, from the Arduino mounting location. Most everything else will be much, much closer. Seems like I read something about using capacitors on long wire runs. I'm not real sure yet how much force will be required from the servo, so I may power it with external voltage, much like I've done on my RC trucks with external battery eliminator circuits.

2

I got a huge shortcut when I found an Instructable

This forum is littered with the mental scars and bandages from the injuries of people who thought those were shortcuts.

Long wire runs can be done, the problems depend on what you are connecting. So please supply a detailed list.

3

Servo
Switch
Arduino Mega

The code has been checked for me here in a different thread, as well as me working and reworking through it as I try to educate myself, and it seems sound.

It's all a learning experience anyway, and th game will be built in such a way that it can be easily scored manually. In case I have troubles getting this working like I want it to, or in case the system ever goes down for some reason.

More information here but I don't think much or any of it matters for this question.

4

So are both the servo and the switch on long wires? Okay. The switch is no problem, I'll get to that momentarily. The servo could in theory run on long wires. For that, you have to ensure that the power (and ground) wire is thick enough that there isn't power loss in the wire. Twist the wires close together. Add bypass capacitors from Vcc to ground. I would put those on the servo end. The switch should function normally, also twist the wires. Add a 0.1uF cap in parallel with the input at the Arduino end.

5

The most recent question I have developed is, will long wires pose any issues for me?

It shouldn't take more than 5 minutes to look up the resistance per meter of the specific wire guage , do some math, and determine the voltage drop across that length of wire using Ohm's Law.
Since you posted at 9:45 GMT and it's 10:37 GMT now, that was 52 minutes ago, which is is 47 minutes longer
than it would take to look up and calculate the voltage drop across the 12 feet of wire, which we can't calculate
because you didn't give us the wire guage (AWG-AMERICAN WIRE GUAGE).

6

Yes, they would both be on long wires.

However, the more I think about it the more I think I want to supply it power and ground from either an external power supply or one of my receiver packs I use with my RC servos. That way there would be no question about it receiving enough voltage or current.

In that case the only long wire would be the signal wire to it. And I would need to run a common ground to the arduino, no?

I'm still interested in your answer as though I WAS powering the servo from the Arduino, just for the sake of knowing.

The job of the servo will be to swing up (or down, my sure yet) to allow the balls to drop and roll down to playing position. It will then return to the original position after 6 seconds. So, it won't see a ton of use, unless we have a really long marathon of games as a tournament or something one night.

The reason I'm not totally sure on how much resistance the servo will have yet and whether I may need to supply it external voltage is that the build I got the code from had one ball return chute that all balls funnel into.

My game will have 6 individual lanes that return the balls to playing position in lanes that correspond to the hole the ball was scored in. Like so

1024×768 117 KB

I believe I want to design it with a rod connected to the servo above the ball return lanes, with flaps that extend just far enough down to stop the balls.

I also may use my router to route a groove on the ball return lanes themselves, and in that groove mount a dowel that the servo turns with divots ground into the cowell that will let the balls release when it is rotated.

Without having it built in front of me I'm not totally sure how much force this will take. I have some fairly powerful steering servos for my RC rock crawlers, but they are power hungry. If I need to get fancy I can use bearings or at least bushings to reduce some of the friction.

I can also forgo the "ball drop" altogether, but there's just something special about having the balls released to you after you press the reset button. It's just for effect but it's one I hope to achieve

7

I'm still interested in your answer as though I WAS powering the servo from the Arduino, just for the sake of knowing.

Still no wire guage. Am I speaking Greek ?

8

It's a very good idea to power the servo separately. The servo control wire can't be bypassed with caps like a power supply wire, so you need to keep it twisted close to a ground wire. Yes, all the grounds need to be interconnected. Even better - use shielded wires for both servo and switch feed.

9

raschemmel:
It shouldn't take more than 5 minutes to look up the resistance per meter of the specific wire guage , do some math, and determine the voltage drop across that length of wire using Ohm's Law.
Since you posted at 9:45 GMT and it's 10:37 GMT now, that was 52 minutes ago, which is is 47 minutes longer
than it would take to look up and calculate the voltage drop across the 12 feet of wire, which we can't calculate
because you didn't give us the wire guage (AWG-AMERICAN WIRE GUAGE).

Oh wow, thanks!
Doesn't seem that you were asking, but most likely 22 awg.

10

I suggest don't try to power the servo(s) from the Arduino. Then you can use two shielded cables, one for the switch and one for the servo signal, the wire gauge won't be important anymore. If you have to use 22 like phone wire, use two ground/signal pairs and make sure (I will say it again) they are twisted. Did I say you should twist them? Do the twist. Gently :slight_smile: I've seen it done with a hand drill - put one end of the pairs in a vice, other end in the drill chuck, walk away until it's tight, then slowly run the drill. I take no responsibility for any consequences of applying that technique, though... you should have a complete twist approximately every 10cm or so. CAT wires are already twisted as supplied, so you can use them unmodified.

Use a fairly low value pull up resistor on the switch input, for example 1.0k ohm, to suppress cross talk from the servo control wire.

11

Doesn't seem that you were asking, but most likely 22 awg.

22 AWG=16.14mOhms/ft
12*16.14mOhms = 193.68 mOhms = 0.19368 Ohms
Voltage at one end of wire ?

12

aarg:
I suggest don't try to power the servo(s) from the Arduino. Then you can use two shielded cables, one for the switch and one for the servo signal, the wire gauge won't be important anymore. If you have to use 22 like phone wire, use two ground/signal pairs and make sure (I will say it again) they are twisted. Did I say you should twist them? Do the twist. Gently :slight_smile:

Thank you VERY much for your assistance and your well-meaning attitude. This is exactly the route I will take.

13

Do the twist. Gently

Or just use a drill like everyone else.

Doesn't seem that you were asking, but most likely 22 awg.

See Reply#4

which we can't calculate
because you didn't give us the wire guage (AWG-AMERICAN WIRE GUAGE).

*If you have to use 22 like phone wire, *

Or you could use one of these:

wire bundle.jpg

wire bundle.jpg

14

What I meant was, it didn't seem like you were really interested in helping. You didn't seem to actually care about having this information to help me, you simply wanted to put yourself on a pedestal at my expense (see post #4).

But yes, you "asked".

15

What I meant was, it didn't seem like you were really interested in helping. You didn't seem to actually care about having this information to help me, you simply wanted to put yourself on a pedestal at my expense (see post #4).

If you step back from you're feelings for a second it will be obvious that I was pointing out that the issue you were
raising is easily and quickly resolved if you know where to look and what to do with the information. My example
simply demonstrates the expediency of using the proper method.
You could have replied:
"Wow, that's good to know ! Next time I'll use that to calculate the resistance and voltage drop. Thanks !"
One would think that it would interest you to know how engineers solve that problem.
If you reread my post and ask yourself:
"What is takeaway here ? What are you left with ?

FYI,

The power supply voltage and current values are specified for each type of servo motors and depend on the application. The common RC servo motors powered from supplies in the range of 4 – 6 V and 100 mA - 2 A.

Let I= 0.10A (100 mA)
.'. V = IR
= 0.10.19368 ohms
= 0.019368 Volts dropped across 12 feet of 22 AWG wire at 100mA
Let I = 2A
.'. V = IR
= 2A0.19368 ohms
= 0.38736 Volts dropped across 12 feet of 22 AWG wire at 2A

16

raschemmel:
If you step back from you're feelings for a second it will be obvious that I was pointing out that the issue you were
raising is easily and quickly resolved if you know where to look and what to do with the information. My example
simply demonstrates the expediency of using the proper method.
You could have replied:
"Wow, that's good to know ! Next time I'll use that to calculate the resistance and voltage drop. Thanks !"
One would think that it would interest you to know how engineers solve that problem.

I got your point.
And you're concerned with how I responded? Haha oh the irony. Would you like for me to also reword your replies into much better responses?

Sometimes, no ALL of the time, how you deliver a message matters as much as the message itself.

Do you expect everybody who says that they are new to this sort of thing to already know the answers, and ridicule them for not having already figured it out?

17

And you're concerned with how I responded? Haha oh the irony. Would you like for me to also reword your replies into much better responses?

I would think that you would be satisfied with getting the information you were seeking. (at least the price was right)

Solving electronics problems is not putting myself on a pedestal. I'm just another technician doing
electronics . It's what I do every day and I haven't told you anything everyone else on this forum
didn't already know. We all use this stuff every day
and the AWG is the bible we use for wire related info.
It's not like a secret. It's the American Wire Guage.
Don't shoot the messenger.

18

With wires that long, keep away from 1. fluorescent lamps , 2. AC powered LED lights, 3. dimmed incandescent lamps. They all generate RF that will interfere with your design, as it stands.

Paul

19

And above all keep well away from electric welders! You need to take every precaution in such
an environment. One inch of wire is a long cable near such heavy-duty interference!

Vehicle electric systems also tend to be very noisy.