gfucka:
I have some stepper motor recoverd from old printers and scanners but I not find the datasheet.
Do you have any info about the voltages used by the printers?
If not I think all you can do is guess the current. You can measure the resistance of the motor coils. If the resistance is high (for example 30 ohms) then the current is probably low - of the order of 300mA. If the resistance is much lower (say 3 ohms) the current is probably about 1amp to 2amps.
All you can do is start with a very low current setting on the driver - the lowest that will get the motor working - and then gradually increase it while keeping an eye (a finger?) on the motor temperature. It would not be unusual for stepper motors to operate at a temperature at which they are uncomfortable to touch for more than a few seconds. The motors on my 3D printer get warm but I have never noticed them so hot as to be uncomfortable to touch.
gfucka:
Hi,
I have some stepper motor recoverd from old printers and scanners but I not find the datasheet.
For a correct driver setup I need to know the rated current: VREF = Rated motor current x 8 x Rsense,
but without a datasheet I not know it.
There is a way to find it with some tricks or measurements?
Thank you so much
Try a DC current through one winding, gradually increasing in 10% steps until the stable motor temperature is about 50C hotter than the environment? Steppers are usually rated for a particular temperature rise. It takes a long time to stabilize in temperature so allow 5 to 10 minutes for temperature stabilization before each increase in current.
For low-duty cycle motors such as used in domestic printers and scanners the max rated current will probably be somewhat higher than this, as its assumed the thing is used occasionally only.
Robin2:
Do you have any info about the voltages used by the printers?
If not I think all you can do is guess the current. You can measure the resistance of the motor coils. If the resistance is high (for example 30 ohms) then the current is probably low - of the order of 300mA. If the resistance is much lower (say 3 ohms) the current is probably about 1amp to 2amps.
All you can do is start with a very low current setting on the driver - the lowest that will get the motor working - and then gradually increase it while keeping an eye (a finger?) on the motor temperature. It would not be unusual for stepper motors to operate at a temperature at which they are uncomfortable to touch for more than a few seconds. The motors on my 3D printer get warm but I have never noticed them so hot as to be uncomfortable to touch.
...R
Thanks for answer
One motor is from scanner with 12V power supply. If I know the voltage can I calculate the current?
I will measure the coils resistance and then let you know.
Do you mean if I "burn" mi finger it means the current is to high?
MarkT:
Try a DC current through one winding, gradually increasing in 10% steps until the stable motor temperature is about 50C hotter than the environment? Steppers are usually rated for a particular temperature rise. It takes a long time to stabilize in temperature so allow 5 to 10 minutes for temperature stabilization before each increase in current.
For low-duty cycle motors such as used in domestic printers and scanners the max rated current will probably be somewhat higher than this, as its assumed the thing is used occasionally only.
Do you means without a driver? So direct to winding?
All the motors I have salvaged have had some form of marking on them.
From that it is often a simple process to google and find a datasheet or somebody else who has used it for a new application.
Sometimes you may have to use the numbers on the motor but omit something from the leadin or trailing parts of the numbers to get going as they can be parts of a specific use code.
Throw the numbers in here or a good focused picture...or both ;D
Its a bench power supply with both adjustable voltage and current-limit controls. If you don't have one you can't do this.
Most bench power supplies are like this. If the load tries to draw more than the set current limit the voltage drops to prevent the current exceeding the limit. Very useful.