Servo is twitching

Other Hardware Motors, Mechanics, Power and CNC
1

I'm trying to power my servo but when powered using about 5.5v (they are rated from 4.75 - 6) the servo starts going like twitching back and forth - if I power it from the 5v on the arduino board it works fine. I tested using a multimeter and it is definitely 5.5v coming from the external power supply.

2

Please post the sketch that you are running, a schematic of your project and details of what the servo is connected to

3 
#include <Servo.h>

Servo myservo; 

int pos = 0;   

void setup() {
  myservo.attach(9);  

void loop() {
  for (pos = 0; pos <= -30; pos += 1) { 
    // in steps of 1 degree
    myservo.write(pos);         
    delay(15);                       
  }
}

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And at the moment I'm just testing the servos from the sweep circuit from arduino servo docs

4

There's no power to this setup. Why?

5

I had forgotten in that, but the servos are powered externally by 5.5v (and 5a) and the arduino is powered by the usb port (Not sure on the name)

6

Hello aarush41

My recommendation is to run a servo turorial to get started.

7

Is this part of those docs ?

for (pos = 0; pos <= -30; pos += 1)

What values will pos have ?

8

I am following https://docs.arduino.cc/learn/electronics/servo-motors, however there isn't anything wrong with the code but it seems like the power, when I plug in my external power supply it starts to twitch however when I plug the servo into the 5v on the arduino board it works fine.

9

The twitching behavior is almost always due to an inadequate servo power supply. Budget 1 Ampere per servo for small ones like SG-90, 2.5A per servo for larger ones link the MG996R.

Never use the Arduino 5V output for motors or servos, as that can damage the Arduino.

A 4xAA pack of fresh alkaline cells will work for 1-2 small servos. Don't forget to connect the grounds!

servo_pwr
servo_pwr1035×538 42.8 KB

10

Here is the for loop for the Sweep example on that page

  for (pos = 0; pos <= 180; pos += 1) { // goes from 0 degrees to 180 degrees

Compare it with your for loop

for (pos = 0; pos <= -30; pos += 1)

What values will pos have in your sketch ?

11

That is because you do not have the - on the external power connected to the ground on your Arduino.

12

Thank you, this worked - I had assumed that I would just plug the - straight to the servo.

13

What about the for loop ?

14

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