@alankilian yes but i'm in italy and amazon.it don't sell the first item
For my power supply i used LM7812 and 7912 as in following schematics

@o_lampe
Yes i need a negative voltage, you are right!
That DAC converter change the value 0Vdc to 10Vdc.
i sayed stupid thing
i have to build a little pcb with MCP4822 12Bit, this one use SPI protocol.
I dont know witch one is the better idea:

1-use another MCU (like arduino or something) for reading the stepper driver's command (EN, DIR, PULSE) calculate the trigonometric function and make the conversion of movement and return a SPI command to MCP4822 for changing the voltage to Galvo driver.

2- Modify ReprapFirmware and use SPI control on it.

What do you think about?

PS
if @g0rg haven't the skill for making a pcb i can make the design of the 1° idea on EasyEDA and release it free and buy the pcb assembled.
g0rg do you have some PCB or Electronic Skills?

Hi, i have the same problem, i have to use a Galvo System with ReprapFirmware..

You declared 4min for 1 logo; but how much power of your laser diode are you using? because if you're using 100% of power you can't increase your speed..

The Galvo System need 2 analogic, mine Galvos want +5v 0v -5v, i think yours want the same.
+5v = 20° or 15°
0v = 0°
-5v = -20° or 15°
The galvo drivers need a power supply +15v 0v -15v (this is a little bit complicate to find)
So your Analog output have another spec, the resolution!
More bit you have more precision you have.
Is important to know how is the resolution of your galvo drivers.

So, someone knows how can modify the kinematics in ReprapFirmware?
Searching online i find out this link
https://github.com/Duet3D/RepRapFirmware/wiki/Adding-New-Kinematics
But i don't know how add a new kinematics, ok i know how add the files .h and .cpp, but i don't know what i have to write inside.
I know the equation of movement, is simple trigonometric funcion.

if the electronics don't have 2 analog output we can use a DAC (Digital Analog Converter), i found a lot of this in the famose online store, that DAC convert a PWM to Analog 0-10V.
Ok, is not a better way to control the galvos but for first step i think is good enough.

someone can help us?