Thanks for the answers. I'm programmer and new to electro-mechanics so I want to learn step by step and avoid mistakes that will waste my time. Know some theory but have no one that I can talk to and to help me with this beginner steps. Had ordered first this step-down converter and will try to test it with some load; and amperemeter to check what it can provide in current. Afterwards I will going to buy and this 60kg servo.