Hi
I've got the Easy Driver 4.4
And a Phidget stepper motor.
I've hooked it up according to
I'm powering it of my lab. supply, and tried both 12 and 24V, but it only draws ~0.4A at 12V and 0.35A at 24V
I know EasyDriver can only deliver 750mA to each coil, but that is still far more than it is drawing, hence resulting in a slow running motor.
So what have I misunderstood or what might be my problem?
Thank you very much!
Kind regards Taras
The driver has a pot which adjusts motor current. The best way to do this is to start at a low value and increase until the motor runs smoothly. The supply current will always be less than the coil current since the motor coils act as an energy converter. That is why the current decreases when increasing the voltage. So your driver behaves excatly as i should. For best motor performance you should choose a as high as possible voltage
According to your link that motor can take a current of 2.5 amps so it may never perform well with an Easydriver and maybe not even with a BigEasydriver or a Pololu DRV8825.
...R
Sorry for not replying, I didn't get a mail when you posted, as I normally do, when I tick "Get notifications".
I have tried turning the pot, and the values I posted is when it is on max.
The Phidget Controller is recommended for the motor, but it is to expensive for my small project.
I need both speed and torque (4800 g/cm and 5-600 rpm are good specs for the stepper), though since I'm not very experienced, I would like to use a driver such as (Big)EasyDriver or likewise.
What would you recommend?
A geared motor perhaps?
Any recommendation is most welcome!
Thanks!
I don't have any suggestion for an alternative motor that might use less current - there are dozens (maybe hundreds) of motors available.
Gears will obviously reduce speed and it may be difficult to get very high step rates with simple Arduino code. stepper motors are not designed for high speed. Gears will also introduce backlash - which may or may not be a problem.
Have you asked Google if there are cheaper drivers that can supply 3 amps or more?
...R
Edited following comment in Reply #6
taras:
HiI've got the Easy Driver 4.4
https://www.sparkfun.com/products/retired/10267And a Phidget stepper motor.
NEMA-17 Bipolar 48mm Stepper - 3303_0 - PhidgetsI've hooked it up according to
http://www.schmalzhaus.com/EasyDriver/Examples/Example1_bb.pngI'm powering it of my lab. supply, and tried both 12 and 24V, but it only draws ~0.4A at 12V and 0.35A at 24V
We are talking about a chopper driver here - the current taken from the supply is typically
a lot smaller than the current through the motor's windings, because a chopper drive
is essentially a buck-converter, so the output voltage is less and output current more than
the supply.
However you must choose a driver that can cope with the 2.5A that that motor needs, which
is expensive because you really need a discrete driver, not a single-chip one for that current
level - for instance a Geckodrive.
It will be cheaper to buy a motor with something like a 1.5A rating, or compromise
and drive at 2A. The DRV8825 seems to be the highest current single-chip chopper
out there, but it will need proper cooling (small fan + heatsink)
Robin2:
... and stepper motors are not designed for high speed.
Low impedance bipolar motors like this are expressly designed for high speed - 1000's
of rpm at 100,000's of microsteps/second - go check it out on any CNC forum.
Unipolar high impedance steppers, however, are limited in speed by back EMF considerations, and
such a motor is much much easier to drive (people who don't realise the difference
often purchase the wrong sort for their needs, as evidenced on these forums).
MarkT:
Low impedance bipolar motors like this are expressly designed for high speed - 1000's
of rpm at 100,000's of microsteps/second - go check it out on any CNC forum.
Apologies for my mistake.
It is not so easy to produce 100k steps/sec with an Arduino.
I will edit my earlier post.
...R
Just ordered the DRV8825.
Hopfully it can help me get enough juice out of the motor.
Thx!
taras:
Just ordered the DRV8825.
Hopfully it can help me get enough juice out of the motor.
"into"
The max for the DRV8825 is 2.2amps IIRC. For that I think you will almost certainly need a heatsink and probably a fan.
Have you seen stepper motor basics?
....R
