Control 3 Servo motors using external power supply(Not battery)

Hi everyone,
I am new to arduino as well as the electrical field but I am really excited in getting know more. My project requires me to control 3 servo motors(model: FP-S148) using arduino uno. I get to know that 3 servo motors will draw too much current and will be harmful to the UNO board if I power them from it (or not even possible to power 3 of them).

So far I could control 1 servo motor powered by either UNO board or a battery. However for 3 motors, I guess one normal battery is not sufficient and I do not want to use 3 batteries for 3 motors. I have a DC power supply(model: HP E3616A) and would like to use it to power all 3 motors. I have no idea how? Is a motor driver missing?(not familiar with motor driver at all)
I tried to power 1 servo using this DC supply and it could not work(red and black pins to DC supply, signal pin to UNO board, the board and DC supply have common ground). It is strange to me because I can power servo using UNO board or battery but not this DC supply. I guess I must have missed out something and I would like to ask you guys for suggestions and advice.

Thanks so much!

Yes you are missing something, perhaps it is your understanding of what a common ground is. It is a wire between the negitave of your power sipupply and the GND connection of your arduino.

Thanks a lot Mike for your reply. I think I connect it accordingly, or maybe my understanding is still wrong. I have attached the photos to show my circuitry. [This particular problem has been solved]

As shown in the photos, the connection between the joystick shield and UNO board can be ignored since they are not relevant here.
I connect the positive end of the battery to the red pin of the servo; both the negative end of the battery and the black pin of servo connect to the breadboard of the same row; connect the ground of UNO to the breadboard of the same row as the former. This configuration works!
However, when I change the two crocodile clips with the ones from the power supply, it does not work anymore.
Another observation is that, when I send the command from my joystick, there are actually some responses:

  1. the servo - it has some tiny noise when I move the joystick, it seems like it wants to move but not enough power
  2. the DC supply - the indicator light switch from CV to CC when I move the joystick, happened at the same time wit the noise

Hope my explanation of my doubts is clear. Please feel free to tell me what is wrong/unclear. Thanks so much!

I have found out the reason why I could not use the DC supply to power the servo. It is kind of funny. I used too little current to drive the servo[10mA]. I realised current can go up to 200+mA while turning and I increased the current from the DC supply and it works fine now! I think I was just too scared :roll_eyes:

I would still like to ask, do I need to use any extra electronic components to drive 3 servo motors by the power supply? I learnt that I need to use a motor driver to control a stepper motor(even 1 motor). I'm not sure if my understanding is correct. Please feel free to correct me. Thanks!

The general rule is assume an amp per servo (perhaps 0.5A for miniature servos, 2 to 4A
for larger high-torque ones). The power drawn from a servo is "bursty" - when moving
and particularly if the motion is resisted it pulls much more current than when idle.

do I need to use any extra electronic components to drive 3 servo motors by the power supply?

You could add some decoupling capacitors across each of the motors, say 47uF to be on the safe side if you want.

Thanks MarkT and Mike for your advice! I really appreciate the rapid reply.