well, here is a hint... it is inside of a pipe organ

this is a dead giveaway, but what the heck

http://www1.odn.ne.jp/katsuuraorgelbau/image_Pipeorgan-Maintenance/Zimbelstern21.jpg

i believe this one operates by the wind pipe (silent) allowing a stream of air to blow on the small windmill and that then turns the axle with the wooden plectrum that strike the bells in a consecutive fashion.

Heiligen Sterne, Batman!