The circuit is based on the control of MCU. The MCU controls different LEDs vertically to illuminate to get the effect of a rotating windmill. The speed of the windmill flashing is adjustable by pushing the buttons. Manufacturered by WHDTS. Easy to install with the provided schematic info. Operating voltage: DC 5V; PCB Material: High Quality RF-4; Size: 1.57"*1.96" We provide customers with English instruction via email. And customers can also download it on "Technical Specification" section. WHDTS has long been engaged in Electronics Related Products wholesale and retail business. Welcome letter to discuss the wholesale business. The bigger the amount is the more favorable the price is. Funny windmill diy kit helps students to learn about the soldering project knowledge of mechanical structure electronic basis skills soldering skill and so on with full of fun.