Lower thread monitoring system comprised of a main control unit Printed Circuit Boards (PCB) and a photo sensor board used for sewing machines; lower thread supplying system comprised of servomotor for sewing machines; bobbin case for sewing machines; bobbin for sewing machines; pre-wound bobbin for sewing machines; hooks for sewing machines; thread trimmer of sewing machines; remaining thread detection system comprised of a main control unit Printed Circuit Boards (PCB) and a photo sensor bo...