A lamp cap can include: a metal shell; an insulating base disposed on the metal shell; an elastic connecting mechanism disposed on the insulating base, wherein the elastic connecting mechanism can include a first metal element connected to the insulating base, a second metal element disposed opposite to the first metal element, and a spring disposed between the first metal element and the second metal element and configured for supporting the second metal element and electrically communicating the first metal element and the second metal element, a main part of the second metal element can extend into the metal shell, when the main part of the second metal element is pressed by a threaded portion of a bulb, the spring can be compressed and the second metal element is movable relative to the insulating base.

A lamp cap can include: a metal shell; an insulating base disposed on the metal shell; an elastic connecting mechanism disposed on the insulating base, wherein the elastic connecting mechanism can include a first metal element connected to the insulating base, a second metal element disposed opposite to the first metal element, and a spring disposed between the first metal element and the second metal element and configured for supporting the second metal element and electrically communicating the first metal element and the second metal element, a main part of the second metal element can extend into the metal shell, when the main part of the second metal element is pressed by a threaded portion of a bulb, the spring can be compressed and the second metal element is movable relative to the insulating base.

A lamp bulb socket includes an isolator seat with a connection port, an end cover coupled with the isolator seat and having a bracket with a hole, a connection guide terminal with a first contact arm, a connection terminal, a guide terminal with a second contact arm, and a turn switch having a rod with gripping grooves at a first end and four arc notches at a second end opposite the first end. The arc notches received in the end cover and the first end held on the hold of the bracket. The turn switch further includes a terminal contact coupled to the four arc notches such that, when the rod is turned, the terminal contact opens or closes a connection between the connection terminal and guide terminal.

A circular connector assembly having a plug shell, a coupling ring and a housing and a method of retaining the housing. The plug shell has a flexible insert-receiving retention portion and a flange provided proximate the flexible insert-receiving retention portion. The flexible insert-receiving retention portion has an insert-receiving opening. The coupling ring has an internal threaded portion and an engagement portion. The internal threaded portion is configured to cooperate with the flange. The engagement portion is dimensioned to resiliently deform the flexible insert-receiving retention portion when the engagement portion is provided in contact with the flexible insert-receiving retention portion. The insert is inserted into and maintained in the plug shell by the flexible insert-receiving retention portion.

A circular connector assembly having a plug shell, a coupling ring and a housing and a method of retaining the housing. The plug shell has a flexible insert-receiving retention portion and a flange provided proximate the flexible insert-receiving retention portion. The flexible insert-receiving retention portion has an insert-receiving opening. The coupling ring has an internal threaded portion and an engagement portion. The internal threaded portion is configured to cooperate with the flange. The engagement portion is dimensioned to resiliently deform the flexible insert-receiving retention portion when the engagement portion is provided in contact with the flexible insert-receiving retention portion. The insert is inserted into and maintained in the plug shell by the flexible insert-receiving retention portion.