This project aims to upgrade the popular DIY Smart Blinds v1.1 with a Nema stepper motor in order to increase the torque for moving roller blinds. For this project, my biggest concern is the size of the Nema motors. The aim of this version is to keep the form factor of the device as small as possible, give it as much pulling power as possible and allow for a standard 12v power supply.
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For this project I will use the Nema 14 Stepper motor. It is small enough at 35mm x 35mm x 26mm. Its 12v and has the torque of 14N.cm (20oz.in.) compared to the 28BYJ-48 motor used in the previous design which is approx. 2.9N.cm. This should make this device almost 5x stronger.
To control the stepper motor, the design should use the A4988 based motor driver. It is a cost effective driver that is capable to control this Nema 14 motor.
I have used the Node MCU ESP8266 processor for many of my projects. It can be easily programmed using the Arduino IDE, its small and it has WiFi built in. Not to mention great community support. Hence for this project I will use it again.
The second option is the NodeMCU ESP8266 WeMos D1. This processor has a smaller form factor and could also be a good choice.
- Nema14 or Nema17 stepper motors get hot when they run, a 3D printed PLA enclosure may not be able to sustain the heat buildup during operation. Testing shows that typical operation only lasts a 5-10sec then pause. Hopefully this should not raise the temperature too high.
- NodeMCU is a better choice because it has VCC in pins. The WeMos D1 needs to be powered through the micro USB port.
- To power the circuit from one 12v power supply, a 12v to 5v Buck converter will be required.