Window Chain Actuator

UPDATED 2019-11-07 (update notes at the bottom)

I made myself a window chain actuator to automatically control room temperature in winter. Actuator uses 28byj-48 12V stepper + ULN2003, Arduino Uno, DHT22 temperature sensor and 16x2 LCD. Everything is powered with 12v 2A power supply.
Design works nice and without issues already for a half a year. I just set desired room temp, 22°C in my case, and if room temp drops or rises over 22±0.1°C actuator starts slowly close or open window until temp goes back to 22±0.1°C.
12V stepper motor version isn't wide spread, but it is mandatory since 5V version is too weak.
Only now I redesigned some parts to fix some things for easier pinting and assembly. But I didn't printed new design, so bear in mind. If something wrong goes please let me know, I will try to fix design or give some advice.

Video how it works and photo of it mounted on the window at the bottom. It's sad I didn't took time lapse of how it moves window... Maybe next time.