Abstract: A portable electronic device includes a combination button and a gravity sensor. The gravity sensor detects gravity variation of the portable electronic device. When the combination button is pressed for a first predetermined time, the gravity sensor begins. When the combination button is pressed within a second predetermined time and the gravity sensor detects no gravity variation, the combination button's power switch function shuts down the portable electronic device. If the gravity sensor detects a gravity variation, the combination button's volume adjusting function can increase or decrease the volume of the portable electronic device according to the gravity variation.

Abstract: A volume control assembly used for adjusting a volume of an electronic device includes a base, a vibration sensor secured on the base, and a control unit electronically connected to the vibration sensor. The base includes a sensing portion, the sensing portion includes a first end and a second end, and the first end and the second end are spaced from each other. The vibration sensor is located adjacent to one of the first end or the second end. The vibration sensor senses vibration of the sensing portion, and sends a vibration signal to the control unit. The control unit receives the vibration signal, and adjusts the volume of the electronic device according to the vibration signal.