Regarding the power supply for the Mini-PCB v2 to be used with Nema17 with voltage rated as 2.7V


Harkant Singh Baryah
 

Please forgive me for my ignorance as I am ultra noob.

I am doctor by profession and getting into the intricacies on OnStep and Creating a DIY GEM mount after finding a post on you tube describing and showing a 3D printed GEM.
I am going forward the Mini-PCB version-2 way. I have got the PCB from the EasyEDA and the BOM has been ordered from two online stores (almost exact as mentioned in the EasyEDA page).  

I have bought two of  Nema17 stepper motors with 100:1 planetary gearbox from StepperOnline -
(https://www.omc-stepperonline.com/precision-planetary-gearbox/nema-17-stepper-motor-l39mm-gear-raio-1001-high-precision-planetary-gearbox-17hs15-1684s-hg100.html).

I noticed that the motor is rated as 2.7V and 1.68A per phase. 

I was thinking of powering the OnStep Mini PCB v2 with 12V (due to another motor I was planning to buy which was rated as 12V), but now I am not sure. 

Do I need any modification in the power input or need to add some voltage regulator in the circuit to use these motors.


Drew 🔭📷🚴‍♂️
 

On Thu, Jan 13, 2022 at 10:46 AM, <baryah@...> wrote:
I noticed that the motor is rated as 2.7V and 1.68A per phase. 
The ratings for the Stepper are used for calculation. The actual values are determined by other parameters. The 12V power supply is fine for your application.


 

No, you don't need different power supply or regulator. You can safely run everything with 12V PSU or car battery. Steppers are current regulated devices and drivers will take care of everything. Question is which input voltage your driver can take (Vmot) and that's only limitation.


Harkant Singh Baryah
 

Thanks for guidance

On 13-Jan-2022, at 9:53 PM, Vladimir <cyberianice@...> wrote:

No, you don't need different power supply or regulator. You can safely run everything with 12V PSU or car battery. Steppers are current regulated devices and drivers will take care of everything. Question is which input voltage your driver can take (Vmot) and that's only limitation.


Cloud You
 

This reducer is not suitable for equatorial instrument. The total deceleration ratio of 100 can not meet the needs of tracking.


Cloud You
 

You think too much. This kind of motor only needs to consider the total input voltage of 12-24V and adjust the output current of the drive module to 1.68a.


Robert Benward
 



Harkant, regarding your selection.  100:1 is probably way to high.  What are the gear reductions in your mount?  Do you have a 180 tooth or a 360 tooth main worm wheel?  Did you go through Khalid's spreadsheet?  What are you printing your GEM with? Plastic?

I went through the selections you are doing now, this is a much better planetary:
https://www.omc-stepperonline.com/ple-series-planetary-gearbox

Add a motor for $15 more.

Regarding operating voltage.  Look at the bottom picture.  That is a Moon Bipolar motor; look at the torque at 12, 24, and 36V.  At high RPMs the torque is much higher.  At zero RPM, it makes no difference because the coils only see 0.67A, regardless of voltage.  That motor is rated at 0.67A and 6.1ohms & 5.4mH. Voltage is not provided but can be calculated, 0.67A*6.1ohms=4.08V.  Reaching the target current is not the only thing that determines torque.  Note the the chart shows all three voltages at 0.67A.  That is somewhat misleading.  At a higher voltage, the current reaches the 0.67A faster, and is at the regulated 0.67A for longer time before the next cycle begins.  At the lower voltages the current barely makes it to the 0.67A level before the cycle ends.  The area under the curve, and amount of time the current is at the set point, 0.67A (being constantly chopped), is what determines the torque at higher RPMs.  As Drew mentioned, the voltage is not an operating voltage, only a reference that was used to calculate or measure the other parameters.  You can do everything with just resistance and inductance.

I hope this helps little bit...(:-<)
Bob