Hello,
For my project I have automate my venetian wooden blinds. I use an 5V 28BYJ-48 (converted 12V bipolar) motor with a NodeMCU ESP8266 and the DRV8825 driver.
Everything works but the wooden blinds only tilt/close for like 80%.
So I guess I need more powerful motor, because I am kinda new in this scene I hope for some advice or experience.
I found an 1.7A Nema 17 motor, is this type of motor way more powerful? Because of the size in my blind shaft, I have only like 4-5 cm width space for the motor.
The model is: Wantai 42BYGHW609 I have added the datasheet as attachment.
I suspect that most Nema17 motors (there are dozens of different models) will use more power than a 28BYJ stepper motor.
The 28BYJ motors have a fair amount of torque due to their low gearing so I am surprised you are having a problem with your blinds. Please post a drawing that illustrates how your system works and give us an indication of dimensions and weights.
Thanks for the reply. The wooden blinds are 2,4 meters long and I think they are like 5 KG weight, so they are a bit heavy.
Because I have convert the 5 volt 28byj-48 motor into bipolar and run them on 12 volt, I am not sure if the original datasheet is still correct, and unfortunately I cannot interpret all the values.
But maybe I have alternative option: I have now connected two motors on one NodeMCU with 2 stepper drivers. Now they are rotate at the same time and the same way.
Can I somehow change the wires so that the two stepper drivers rotate a different way? If this is the case I can connect both the motors on each side and they will generate enough power, to open and close.
Oke thanks good one! I hope I can decrease the voltage when I run two motors.
Sorry, I do not understand which 2 wires I need to swap, the 28byj-48 has 4 coils? In the convert I had to disconnect the red wire. This is my diagram, now I have added a second motor in parallel with a extra stepper driver. Could you please tell me which 2 wires I need to switch? I think this will finish my project.
28byj-48 has 2 seperate coils. The middles of the 2 coils were connected with the red wire - which you removed and cut the PCB, so both coils are seperate and the thingie works like a bipolar stepper. That's the whole point of the process
Ah great! Oke I think I get it, so pink and orange is one coil and yellow and blue is one coil.
So if I switch the orange pin with pink, it should fix the job, and the motor will change direction?
I have checked and test and the orange and pink is indeed one coil, the motors are now on both side and the blind is now closing for like 92%.
So dancing naked in my living room is still tricky and I do not want to upset the neighbours
And I have 4 venetian blinds so eight 28BYJ motors on one nodeMCU is maybe to much.
So I am still wondering if the Nema 17 will do the job, this will cost me alot of time again for 3D printing models and adapters so I hope someone has some good advise.
An MG995 servo is maybe stronger? But then I should change my script at nodeMCU and buy different drivers.
Motor torque (not gearbox output torque) is proportional to coil current, so with a proper driver and power supply, the 1.7 Ampere/winding motor would have around 6 times the motor torque of the wimpy 28BYJ motor, at 0.24 A/winding.
You would still need to gear down the bigger motor.
Motor torque is proportional to current times the motor constant, which differs between motors
and between different voltage windings for the same basic motor. So you can't compare
different motors' torques by current like that.
Read the datasheet to get the data on each motor.
Note that dynamic torque for a stepper is always a lot less than holding torque. Good
datasheets give graphs of torque v. speed for several supply voltages, otherwise its
pretty much guesswork.
The tiny 28BYJ48 is much punier than a "proper" stepper, only the gearing allows it to
produce usable torque.
