how to choose the right power supply for multiple servos

Hey everyone, I'm working 6 axis robot arm with a smartphone control project from youtube but I'm having some issues with it. whenever I tried operating it the servos either wouldn't move or they would all start to jitter. I think its the power supply that I'm using which is a wall plug 5V 2A DC power supply.

I'm trying to power 3 SG90 Micro Digital Servo Motor SF0180 TowerPro RC 9G and another 3 mg996r Tower pro servos.

the micro servos have a running current of 140mA and 520mA stall current at 4.8V

the big servos have a running current of 500-900mA and 2.5A stall current at 6V

I'm not exactly sure what it means to stall a servo but I hear it's not something that should be happening anyway in a robot arm

I am connecting everything on a breadboard

I don't know if you'll need the code or wiring diagrams since this is about power supplies but let me know if its something you'd need so let me know if you need me to post them

Here is the link to the video

Here is the link to his tutorial on his website with the wiring diagrams and code

The stall current is what is drawn when the arm is trying but unable to move a heavy load. However when a DC motor starts from stationary it can also very briefly draw the stall current until it actually starts moving.

Consequently you should choose a power supply with ample current to match the stall current of all motors that could at the same time. And by ample I mean at least 50% more so that the power supply is not overloaded.

Also a solderless breadboard is not intended to carry the levels of current needed by motors - you might get away with connecting the small SG90s that way but not the bigger servos.


would you recommend perhaps a 5V 4A power supply or a 5V 3A one?

thanks again for the help. very much appreciated. :)

Always go for the biggest amps you can. You can never have enough of em.

Also allows you to add other items if needed at a later stage.

"would you recommend perhaps a 5V 4A power supply or a 5V 3A one?"

If you can find a 6v power supply, you might consider that as typical hobby servos have more torque at 6v than 5v.

Stick to 5V because then you can easily run other components like the Arduino from it. But for 6 servos including 3 x MG 996s I'd want at least 5V 6A preferably more. And get rid of the breadboard. At least for the big servos you need more solid connections.

NOTE: you don't have to be trying to move a servo to get close to the stall current. Just holding a heavy load in position has the same effect...and robot arms do that sort of thing all the time.