What external power supply do I use?

So I have this project where I will be using 6 different servos on my Arduino board

The Servos will be connected to a breadboard, and the Arduino UNO will have a USB host shield on top of it.

These are the Servos I will be using: http://littlebirdelectronics.com.au/products/hitec-hs422-servo

I was wondering how to power these up externally As I know the UNO won’t have enough power,

Do I need to supply above 20 volts as they require 4.8-6v and I am using 6 of them?

Please point out any power issues you might find with the USB host shield.

Use a separate 5V or 6V power supply for the servos, connect the GND of that to the Arduino GND. Example: http://www.mpja.com/5-Volt-DC-Plug-Power-Supply-4A-Regulated/productinfo/18520%20PS/

Find something similar where you are located (AU?).

Do I need to supply above 20 volts as they require 4.8-6v and I am using 6 of them?

No you connect them in parallel, as shown in the pic attached.

I know the UNO won’t have enough power

In fact, it’s unwise to power even one servo from the Arduino: forum wisdom is to allow 1 Amp per servo. So if it’s likely that all 6 of yours will be maxing out at the same time, even that 4A supply that CR linked may be stretched.

servo power.png

That particular servo at 6V is quoted as 0.37Nm and 7 rad/s (converting imperial units to something sensible), so the mechanical power can be estimated:

power = torque x speed = 0.37 x 7 = 2.5W

Allow for loss in the motor, gears, circuitry and it ought not to take more than about 1A (6W electrical) during operation. Servos only draw full power briefly when accelerating or when moving against a heavy mechanical load, so with 6 servos its not clear how many amps you need without knowing how many are going to move simultaneously.

ok thanks guys, so a 6 volt battery should do? and don't connect any of the UNO's power pins to the servos.

Will my servos be drawing to much amps? is it dangerous to the arduino or servos?

Give the servos about 6V, common only the GND with the Arduino, all should be well if the batteries provide enough current, else the servos will underperform, the battery will struggle, but the Arduino's only sending PWM signals so its safe.