Pages: [1]   Go Down
Author Topic: When is a motor shield/external power supply necessary for servos?  (Read 455 times)
0 Members and 1 Guest are viewing this topic.
Offline Offline
Newbie
*
Karma: 0
Posts: 2
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

I want to do a robot using 2 continuous servos (5V, 15-200 mA) and 2 smaller regular servos (5V, no current info, but its this one: http://www.servodatabase.com/servo/emax/es08a).

My question is, at what point (current load, number of servos, etc.) do you need to use a motor shield or some other method to control the servo?

Thanks in advance!

-BritKnight
Logged

Offline Offline
Faraday Member
**
Karma: 66
Posts: 2570
Now, More Than Ever
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset


I think that the "limit" is 3 (or three-ish.)
All you need is a 5V source exclusively for the servos; you don't want to run 4 from the Arduino's 5V, that's excessive demand for it.
Logged

"Hello, I must be going..."
"You gotta fight -- for your right -- to party!"
Don't react - Read.
"Who is like unto the beast? who is able to make war with him?"

Offline Offline
Newbie
*
Karma: 0
Posts: 2
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Thanks for your response!

Just a little bit of a curiosity follow up question:
What makes you say 3-ish? Does the PWM get a little imprecise when the arduino is running a bunch of them? Sorry for all the questions, I'm new and just want to make sure I understand.
Logged

Offline Offline
Faraday Member
**
Karma: 68
Posts: 2791
The last thing you did is where you should start looking.
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

It depends on the "actual" current each motor needs.
3 motors may be at the tipping point that the Arduino can drive.
Logged

The way you have it in your schematic isn't the same as how you have it wired up! That goes for me too.

Johannesburg. UTC+2
Online Online
Faraday Member
**
Karma: 105
Posts: 4658
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Best place I've found to read about servo powering is DuaneB's stuff

So yes the decision on external power or Arduino 5v is a current thing, but it's so little hassle to hook servos up like DuaneB shows, it's worth doing as a matter of course even for 1 imo.

From a control (as opposed to power) point of view, the servo library has plenty of connections for your 4.....
Logged

The Elders of the Internet know who I am
I'm on LinkedIn: http://www.linkedin.com/in/jimbrownza

Pages: [1]   Go Up
Jump to: