One aspect is a friction hinge system including a housing having an inner surface, an outer surface and defining a substantially cylindrical opening and a longitudinal slot. The rotary valve is connected as a bypass parallel to a supply line between a consumer or load and a positive and negative pressure source. Methods relating to implementing the virtual-reality photo gallery are also disclosed. The processor evaluates samples of the accelerometer in an evaluation period and decides whether to continue in the active mode or return to the reduced power mode. A mixed emission suitably blended of the direct and indirect light is directed to directions, which are modified to directions around a roughly frontal direction by prism sheet PS before being supplied to a LCD panel or the like to be illuminated. The third circuit may also be adapted to couple a set of removable programming keys that provide for a different associated DC output voltage.