The invention relates to a device for evaporating volatile substances, comprising a heat source (5) evaporating volatile substances from a refill (2), a heat detector (4) which can detect the heat from said heat source (5), and indicating means (7) connected to said heat detector (4) emitting an indication when the heat detector (4) detects the heat from said heat source (5), and characterized in that said heat detector (4) is placed above said heat source (5).The invention allows the indicating means to be activated virtually in a simultaneous manner with the placement of the heat emitter.
