Arduino Mega - Digital Servo with External Power Source (Stepped down to 5V)

Projects General Guidance
1

Hello, I have been trying to get a digital servo to run as shown in the attached image. When I connect everything and run the code, the servo makes a weak sound but doesn't spin. I am measuring 5V across the output of the linear regulator. Here's a couple things I've checked and have gotten to work all with the same code running in the Arduino (so the code I have is not the issue):

  • The exact same wiring shown except with a raw 12V input and no regulator (Servo is rated up to 7.2V so I can't continuously run it at 12V)

  • Same wiring shown but with a voltage regulator adjusted down to 5V (to insure servo runs at 5V - it does)

  • Plugging servo red lead into +5V on Arduino and black lead into ground on Arduino. I know this is not recommended but the servo did move, though somewhat irregularly.

Could anybody help me with this?

(mod edit)

servo.PNG
servo.PNG1285×734 95.3 KB

servo.PNG
servo.PNG1285×734 95.3 KB

2

Connect all GND (-) lines together, using the blue (-) contact row on your breadbord.

Feed the servo with enough current. The Arduino regulated 5V output is not suited to drive motors. Use a battery directly or a voltage regulator rated for the servo current. Voltage regulators often shut down their output when the load (servo) draws too much current - check!

3

Hi,
Welcome to the forum.
I think we need to see your code.
What is your code supposed to make the servo do?

Thanks.. Tom.. :slight_smile:

4

Is it a 9g servo or a full sized? An arduino 5V out will power a 9g servo usually, but if you have a full sized servo probably it won't like it. How many amps can your voltage regulator put out?

5

You forgot to say what type of servo you are trying to run and what voltage regulator you have. Details matter.

But trying to run any servo from either a 9V battery or the Arduino 5V pin is asking for trouble. Try it with 4 x AA batteries (prefereably NiMH rechargeables) and no regulator.

Steve

6

slipstick:
Try it with 4 x AA batteries (prefereably NiMH rechargeables) and no regulator.

Because that is for what servos are designed!

7

DrDiettrich:
Connect all GND (-) lines together, using the blue (-) contact row on your breadbord.

Feed the servo with enough current. The Arduino regulated 5V output is not suited to drive motors. Use a battery directly or a voltage regulator rated for the servo current. Voltage regulators often shut down their output when the load (servo) draws too much current - check!

Hi, I've been powering the servo with a seperate 12V power supply. Without the linear voltage regulator involved, the servo runs no problem. When I introduce the regulator, the servo does not run. I have measured the voltage across the output and it is indeed outputting a voltage. I tried connecting the ground of the power supply to the Arduino ground as well and still no luck.

*Edit - Is it possible the voltage regulator is outputting 5V but shutting down current? Would it not show as 0V?

8

Hi,
What regulator are you using?
Have you got it bypassed with capacitors as suggested in the datasheet.

Can you post a hand drawn schematic with the 12V power supply and the regulator included?
Please post your test code.

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

9

If you're not going to answer any of our questions we can't answer yours.

Steve