A sound emitting device can include electrically powered components that emit sound. In addition, the device can have a sensor capable of detecting movement of the device, and an electrically powered circuit. When the sensor is activated, the circuit can send a signal to the device to cause the device to emit sound. An attachment device can couple the device to a person, animal, bicycle, other device or a combination thereof.

A safety system for bicycles includes a radar, a controller, and a warning apparatus, which includes a tube, a vibrating motor, and an impact sounder. The vibrating motor includes a rotary shaft and an eccentric block. The impact sounder includes an elastic member and an impact block. The elastic member includes a first end fixed to the inner wall of the tube and a second end connected to the impact block. When the controller decides to issue a warning based on a radar signal, it outputs a control signal to drive the rotary shaft to rotate. The rotation of the rotary shaft drives the eccentric block to rotate and vibrate, and the eccentric block strikes the impact sounder to make the impact block hit the inner wall and thus generate an impact force and emit a sound. The warning apparatus simultaneously provides the bicycle rider with vibrating, impacting, and audible warning.

A motion-activated mechanical sound-emitting device includes at least one ringer and at least one striker supported outside the ringer. A user actuator selects between an on state, in which motion permits the striker to contact the ringer to emit sound, and an off state, in which contact is prevented by moving one or both components away from one another or by interposing a blocker. Striker-support components remain outside the ringer, with no portion disposed within or passing through the ringer. The device is operable in any orientation and, in some embodiments, is spring-free and provides intermediate positions for partial sound reduction. The device can be mounted to a wide variety of moving hosts, such as a bicycle, backpack strap, pet collar, horn of a saddle, wheelchair, motorized scooter, or robot, and may employ multiple striker-ringer pairings.

A sound emitting device can include electrically powered components that emit sound. In addition, the device can have a sensor capable of detecting movement of the device, and an electrically powered circuit. When the sensor is activated, the circuit can send a signal to the device to cause the device to emit sound. An attachment device can couple the device to a person, animal, bicycle, other device or a combination thereof.