Powering 2 steppers and 2 servos

I'm putting together a pen plotter that uses 2 stepper and 2 servo motors.

From what I can find online, the power requirements are:

Stepper motors (sm-42byg011-25) : 12V, 0.33A
Servos (SG90) : 5V, 0.5A

The steppers will be driven by two EasyDriver modules and controlled by an Arduino Uno (or maybe a Nano).

I have a few questions (I have no formal training in electronics!):

- Can I run the steppers at higher voltage?
I read that it would give better performance at high speed. Maybe go to 20V?

- How do I work out the total current draw?
Are the values on the datasheets typical? max? Do I just add them up, 2x0.33 + 2x0.5 = 1.66A

I suppose I can just get a 2A or 3A power supply and it should probably be enough (based on what other people have used on similar projects)

- Isn't it odd that the tiny servos draw more current than the larger stepper motors?

- I'll need a step down module to go from 12V (or higher) to 5V. Anything to watch out for?
From what I can see even the cheaper ones on eBay can supply 2A, so that should be ok for the 2 little servos.

- I'll probably power the Arduino from USB. Is that ok?

- Will I need any heatsinks for anything?



Stepper motors work better with higher voltages. The upper limit is what the Easydriver can accept.

You must not exceed the stated voltage for the servos.

The current of the stepper motors will be as stated in the spec. However you need to allow for the stall current of the servos which will be considerably higher (like 5 times(guess)) than the running current. I don't know if your 0.5A figure is the running current or the stall current.

Stepper Motor Basics
Simple Stepper Code