A locking structure for a notebook computer with a main body and a monitor covering the main body. The device comprises a delay lock loop to provide an output signal based upon a phase difference between a reference signal and a feedback signal, said delay lock loop comprising at least one delay circuit comprising a plurality of logic gates configured to provide for substantially uniform degradation of a plurality of NAND gates in a static state. A valve assembly includes a housing defining a first port and a second port. To protect the door from being damaged by collisions, the track can include a breakaway feature that allows at least a portion of the panel with its drive strip to separate from the track without permanent distortion. Then, a solar light tracking sensor is fastened to the rear end part of the guide in place of the optical telescope.