choosing a power supply

hi guys

im working on my cnc project !! and im using 4 easy driver modules to control my steppers !! and im using 15v power supply with max 2A current to power up the drivers !! (which wont satisfy my requirement)

as in total the max current, which one easy driver require is 750mA so with calculations ill need a total
of 3000mA = 3 A

and i have another power supply which has 15v 4A at peak

and i power all the driver from one terminal so the load will be as in one !

so is it okay if i use my 4A power supply?

and i wanna have a current clipper circuit for each module to stop exceeding max current of 750mA in a mechanical failure

your ideas would really help me alot

thank you

No, you don’t understand stepper drivers.

They are current controlling buck converters - the current out is usually substantially more than
the current in.

The individual drivers need to have their current level set to match the motors (which motors do you
have? They need to be low impedance bipolar with no more than 0.7A current.)

The current requirement from the power supply depends on the supply voltage, and the power used by
the motors, and the efficiency of the drivers at the current level they are set to.

The problem here is i salvaged my steppers from an old photocopy machine and all 4 motors are not even same brand and i have no data on it !! but all the motors work on 15v and 2 a power supply !! and the driver will need more current to work with the given instructions !

so what would you suggest me to do ?

As I said you need low impedance bipolar steppers with a current rating of 0.7A or below. You will
have to determine if those meters match that requirement.

For the current you could feed a constant current into one winding for 10 minutes and see how hot
the motor becomes - increase till the motor is definitely hot - that's then a good guess at the
working current.

If the voltage needed to do this is more than 10V, you won't have much joy running from only 15V
into the Easy Driver, you need decent voltage overhead for a stepper driver to function.

Its typical to run motors of a couple of amps, 1 ohm or so from 24V or higher using a stepper
driver - lots of voltage overhead allows higher speed operation.

It strikes me you don't know if the motors have enough torque for your application anyway...

You need to figure these things out first...

the only infor which is printed is the step angle which is 1.6 and 1.1 ohms on each motor ! but different brands !! and when power two can hold 1.4 kg at 15 V and only uses 0.4 mA !!

i wanna have input current clipper to restrict more current flowing to the driver !! to protect it !!

15V 0.4mA ? No, that's crazy. Steppers are typically between 0.5 and 50 ohms.

Some older steppers are damaged by over current, note, as the kinds of permanent magnet
used have low coercivity and can be re-magnetised by over current or simply by dismantling
the motor. Cheaper motors tend to be ferrite magnets which are pretty safe from this though.

The step angle is 1.6 and 1.1 ohms?

Photos, part numbers please, lets get the real deal here...

yes my power supply shows only 0.48(varies) not more than 0.5 current drawn when when single stepper pulling 1.4kg at 15V

and sorry its hard to see the step angle is 1.8 degrees
an image is attached for ur info

okay so to confirm i removed all the other drivers and hooked up only one driver to my power supply

note i power 5v to easy driver from arduino and 15v to m+ and gnd pins in easy driver

and the current for initial torque is around 4 mA and reduces to 0.3 mA and the axis has no problems in movement !!

yes my power supply shows only 0.48(varies) not more than 0.5 current drawn when when single stepper pulling 1.4kg at 15V

Your power supply shows 0.48 what? You said 0.4mA before.

Please be precise, its wasting everyone's time to say 0.4mA when you mean 0.48A.

sorry its 480mA !!! i didnt mean to waste others time !! and everyones not perfect !! n i thought forums are there to learn correcting mistakes !! but thank you !! ill do some more research on this !!