Servo issues

Other Hardware Motors, Mechanics, Power and CNC
1

Hi guys,
Im building a DIY robot arm and i'm using mg996r towerpro servos. I've hooked them up to 6v battery pack and made a common ground. They've always worked with my code, but now they wont. I tried taking digital multimeter and reading the values. When i connect the servo motors, the voltage level drops to between 0 - 1,5 volts. The voltage differencial stays after i remove the servo, and when i touch VCC and GND pins on servo it cancels out. Help please

Massimo

2

Hi,
Welcome to the forum.

Please read the first post in any forum entitled how to use this forum.

Can you post a picture of your project and can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?

What sort of batteries are you using?
How many servos?

Thanks.. Tom... :slight_smile:

3

I made a small circuit to try and solve it on my own but i couldn't. I used 4 * 1,5 volt AA batteries and 1 servo. An amazingly good drawn circuit is attached :slight_smile:

Servo setup.png
Servo setup.png1152×648 236 KB

4

Hi,
Does the power supply drop when you use your small circuit?

Have you had the servos working previously?

Can you please post a copy of the sketch you use for the simple circuit, using code tags?

They are made with the </> icon in the reply Menu.
See section 7 http://forum.arduino.cc/index.php/topic,148850.0.html

Thanks.. Tom.. :slight_smile:

5

I've had all the servos working. They all suddenly couldn't go.
The code for the simple program that didn't work:

#include <Servo.h>
Servo servo;
int servoPin = 4;
int firstLocation = 20;
int secondLocation = 160;
int delayTime = 2000; 


void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  servo.attach(servoPin);
  delay(50);

}

void loop() {
  // put your main code here, to run repeatedly:
  servo.write(firstLocation);
  Serial.print(firstLocation);
  delay(delayTime);
  servo.write(secondLocation);
  Serial.println(secondLocation);
  delay(delayTime);

}

The voltage also drops on the small circuit, and it almost seems like the servo builds up a battery inside of it in the opposite direction, that cancels out the 6v coming in.

6

massimohansen:
I made a small circuit to try and solve it on my own but i couldn't. I used 4 * 1,5 volt AA batteries and 1 servo. An amazingly good drawn circuit is attached :slight_smile:

AA is a size of battery, not a sort of battery. What sort of batteries? NiMH? Alkaline? Zinc-carbon? part number?

7

Ah okay, sorry, they are Alkaline batteries, and the package also has LR6 and MN1500 on it. :slight_smile:

8

Yes, get some NiMH's designed for high current application, servos are high current. The sort of
battery pack used in RC toys for operating servos is a sensible choice(!)

9

Ok thank you Mark, i'll try and do that :slight_smile:

10

But if the alkaline are holding a good enough voltage when working don't worry immediately.
Rechargables are cheaper in the fairly short term for high current draw - just don't abuse
rechargables (never over-discharge).

11

Hi,
Let me get this straight,
if you connect the brown of the servo to battery neg
and red to battery pos
and nothing else, just the servo, the Arduino is not connected at all.
and that is the only thing connected to the batteries, the battery voltage drops?

Am I correct?

If so have you replaced the batteries, have you tried ALL you servos separately?

Thanks... Tom.... :slight_smile: