elsharkawey:

are't 12v are the Maximum for his motor ?

no, stepper motor voltage is just a number picked from doing coil and current measurements.

the coil gets charged by voltage, the speed of the charge is dependant on the voltage and current.

if you know the current and resistance, ohms law gives you a number for voltage.

but, with that number you can figure how well it will perform.

using that derived number, and applying that voltage, the motor can be charged with an open circuit to the power supply. in other words, no resistor or special circuit is needed because the wire size/resistance/turns will allow the coil to be charged to a current that can be both achieved and sustained by said voltage.

now, if you double the voltage, you can over power the coil, so you chop the power once the current has been delivered.

the neat thing is that if you double the voltage, you cut the time it takes to charge the coil in half. that means that you can spin the motor twice as fast. however the coil is an inductor and as you try to charge it faster, you find that inductive reactance prevents a simple double voltage = double speed result.

but higher voltage does mean higher speeds.

torque is proportional to current. so if you use 12v and can charge the coil 700 times a minute you get x torque

if you double the voltage and can spin the motor 1,000 times a minute, you get over 50% more torque.

it is not linear, but you can power a stepper to about 30 times it's nameplate voltage with a GOOD quality driver AND a HIGH QUALITY pulse signal.

just because you send 2k ppm does not mean they are evenly spaced and or crisp signal values.

now, about the maximum voltage for the linked motor, the practical maximum voltage is under 400 volts, but since you cannot get circuits for that, and it would be silly to try, the very low end hobby drivers we do use, like the A4899 have a practical 24 volt limit. stepper motors are really just coils. and coils have an inductive kickback or back EMF. this can easily be 120% of the power supply voltage. So the spec sheet says you can run a motor up to 35 volts, but without really top notch circuitry, you can expect that with a 24 volt power supply, the driver might see over 30 volts from the back emf.

to compare torque, if you used the same motor, but rated for 5 volts, it would cost a little more, but be able to deliver more than twice the power.

alas, in the hobby arena, such things are not that important and most suppliers are trying to be 2 cents cheaper than the next guy. you would be hard pressed to find a 1.2 v stepper from the usual sources.