Buzzer in a Vacuum Vessel

An effective and compact alternative to the traditional Bell in a Jar apparatus. Comprising a strong acrylic vessel, with a simple buzzer circuit. The vessel has an outlet through which air can be evacuated using a vacuum pump (not included). The buzzer is mounted on foam to reduce transmission of sound to the vessel walls.
When the air is evacuated, the sound of the buzzer is attenuated, as there is no air through which the sound is transmitted to the walls of the vessel.
Dimensions (H x dia): 140 x 100 mm