Need an advice on choosing the wire

Projects General Guidance
1

Hi guys,

So in our project we use 50 servos that are spread out in space and need long wires (it seems we need more than 2000 ft). I found this dog fence wire on amazon and it seems that price-wise it's the best option so far: https:

www.amazon.com/PetSafe-500-foot-1000-feet-20-Gauge-Boundary/dp/B01GGJYOI2/ref=sr_1_3?rps=1&ie=UTF8&qid=1469408561&sr=8-3&keywords=solid+core+wire+1000'&refinements=p_85%3A2470955011

Would you advise if this one will do for the situation or advise any better option? Please.

Thanks

2

From a personal standpoint and the long distance you need I would go with a shielded twisted pair at least.

Using un-shielded cable over long distance could introduce unwanted behaviour in your servos.

3

That is only single conductor wire. You need 3 for a servo, power, ground, and signal.
I think you would be better off wire shielded 3-conductor wire.
For example:

I use this at my fencing club to bring 12V, Gnd, and a 4800 baud control serial signal from the scoring box to a remote box that reads the signal and finds the data to turn on/off the scoring lights. Runs are 50-70 feet long.

4

Hi,

The wire diameter will depend on the current consumption of your servos.
What are the specs of your servos?

With 50 servos, your supply for them may need to be 3 or 4 supplies rather than 1, so you can even-out the current distribution.
Voltage drop over long lengths of wire will be you main problem, so cheap is not necessarily the best.

In what configuration do you aim to power the servos, star from a central supply, or daisy chained on the one pair of wires?

Tom... :slight_smile:

5

Calculate volt drop at the stall current of the servos.
You most likely will have already serious issues there.
20-gauge is 10.15ohm/1000ft.
If you use shielded wire, or Cat-6 wire, calculate capacitance.
The square servo pulses might end up like triangle waves.
Draw/post the complete layout, and link to parts you are going to use.
Leo..

6

Solid core wire will probably break due to vibration or movement. Use stranded wire.

This sounds like a situation where it may be wise to use multiple Arduinos so that they are close to the servos they control. You could probably communicate with the Arduinos using wireless.

You need to provide a diagram showing the layout and the distances.

...R

7

Thanks for all the replies. I thought this cable may not work. For the details;

  • the longest wire per servo will be 28 feet
  • The servos we use are Tower SG92R
  • The setup is 1x Arduino Mega + 4x 12 bit 16 channel Servo drivers + 2x external 5v 10amp power supply for all 50 servos (powering 2 drivers each) + 9v power supply for arduino + 10 photocells (triggering servo motion)

Stranded wire will be an issue for the way we connect servos to driver pins. We'll check home depot tomorrow to check that 3-conductor wire. Maybe also will try to rearrange the positions of 4 drivers.

8

etagita:
Stranded wire will be an issue for the way we connect servos to driver pins.

Find a solution. Don't consider solid core wire.

And crimped connections are better than soldered connections if there is any risk of movement of the wire.

...R

9

Made a comment about long servo cabling a while back.
PDF attached explains most of what can happen.

Servo Power Buffering-V0.5.pdf (57.4 KB)