An assembly comprises an electric consumer, an electric voltage source adapted to power the electric consumer, and user operated actuation means. The electric voltage source is operatable between a first state in which a first voltage is generated and a second state in which a second higher voltage is generated. The user operated actuation means is operatable from a first to a second state and adapted to thereby operate the electric voltage source from the first to the second state, and operatable from the second state to the first state and adapted to thereby operate the electric voltage source from the second to the first state.