Could you explain what this circular circuit is on the first image? What's it used for? Also, what is this 3 pins on the 2nd picture? <img width="368" alt="Screen Shot 2022-02-27 at 12 28 26 AM" src="https://user-images.githubusercontent.com/44885838/155874818-81edd083-6e8e-40ef-949f-e8ce42a116e7.png"> <img width="368" alt="Screen Shot 2022-02-27 at 12 30 31 AM" src="https://user-images.githubusercontent.com/44885838/155874817-e8d96857-e806-4254-89de-6fea9cafa395.png">
Could you explain what this circular circuit is on the first image? What's it used for?
Also, what is this 3 pins on the 2nd picture?