Controlling Servo motor

I am using using Arduino UNO.

The servo motor i am using is Futaba s3003.

The code I am using is SERVO->SWEEP from the library of Arduino IDE.

Using power supply(with voltage regulator 7505) to power servo motor and arduino is powered from my laptop.

I working on walking robot project. For this i brought 6 servos i stated above.Coming to the problem, when i upload my code to arduino board, the servo dont work according to the code. Everytime switch power on,Servo goes to 180(angle) and comes a little back and pushes itself to 180 again ang until i switch the power off. Infact i goes to 180 so fast that it broke the bumper inside the servo and hence damaged my two servos. : :confused: :confused: . I also tried to power the servo from Arduino itself but this time when then servo goes 180 deg the board reset again and again.

One more thing i also brought Tower Power servo 9g.
and it is working fine according to the code.

Please Help.

Have you got the grounds connected?
Is the power supply capable of providing 1amp per servo?
Is the 7505 capable of providing 1 amp per servo. Oh, wait . . .

Yes, the of the servo and Arduino is grounded to power supply ground.
And.. No , voltage regulator 7505 is providing 0.5 amp only.
Can u tell what modification should do to my power supply now ?

@awol thnx for such a fast reply :slight_smile:

What is your power supply?
Is the power supply ground connected to the servo grounds and the Arduino ground?

Yes .. The ground of the servo and arduino is connected to power supply ground.

I made my power supply using 12-0-12 transformer using bridge wave rectifier and then i used Voltage regulater 7505 which is providing 0.5 amp at output.

Try replacing the power-supply with four AAs, and see how that goes.

I didnt get that 4 AA ?!!
Are you talking about the batteries ?
Then please specific the output voltage and current of those batteries.

Or these 9 volt batteries will do ?(please see attachment)

Standard AA (aka R6) 1.5 V cells.
Use four of them to get 6V connected directly to your servos. Do not use your regulator

No, 9V batteries are not suitable.

:o Wow it worked like charm ??? Servo is behaving properly. The code is working fine.
But the thing is i want to use 8 servos(futaba s3003) and AAs wont last long enough for them. So therefore want to use Power Supply. So can you plz help me on how much amp of transformer should i use (0.5 amp or 1 amp).
And one more thing i was operating servo at 5v using 7505. If i use 7808 to operate servo at 8v to produce brtter torque , will it damaged servo or it would work fine??

Budget around an amp per servo at no more than six volts


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

Especially your voltage regulators and power supply.
Have you placed the capacitors around the regulators that are shown in the regulator datasheet?
What does your 5V form the regulator measure when the servos fail?
Without the caps around the regulator then its regulation is not good.

Tom.... :slight_smile:

Hii… Tom

This is the circuit of power supply(in attachment).
Yes, I have placed capacitor around voltage regulator.
I was thinking of placing 0-12 transformer of current 1 Amp as AWOL suggested that it will need 1 amp per servo.

Now the question is, should i place a transformer of 1 amp at output?? Or if there is any other solution please suggest.

Thanks for your reply Tom and Awol.

Read the data sheet for the 7805, you need some lower value caps as well.
Page 7.
The 1000uF cap will have to be bigger too, 4700uF.

Tom… :slight_smile:

LM7805 (1).pdf (351 KB)

Ok I will try 4700 uF cap and tell u about its outcome.
Stay connected :slight_smile:

Using 4700uF didnt work. Servo behaving strange as i explained above.

Servo worked with 4 AAs … But how to use this servo with power supply ?? What transformer should i use ?

Awol plz answer

What is the measured output voltage of your power supply? You can add a small diode like in the attached pix to raise the 7805 output voltage from 5.0v to 5.7v for better servo performance. A laptop pc power supply with a UBEC voltage regulator might make a goo multi servo power supply.