Abstract: In one or more embodiments, a fan circuit may be configured with an input of a first amplifier coupled to a revolution indicator associated with a fan; an output of the first amplifier coupled to an input of a second amplifier; and a power supply input of the second amplifier coupled to a first contact of a first connector. In one or more embodiments, the first contact of the first connector may be coupled to a first contact of a second connector to drive a resistive load coupled to the first contact of the second connector; a second contact of the first connector may be coupled to a second contact of the second connector to provide a reference voltage to the second amplifier; and the second amplifier may provide amplified signals to the first contact of the first connector based at least on signals received from the revolution indicator.

Abstract: A photo-detecting device includes a first semiconductor layer with a first dopant, a light-absorbing layer, a second semiconductor layer, and a semiconductor contact layer. The second semiconductor layer is located on the first semiconductor layer and has a first region and a second region, the light absorbing layer is located between the first semiconductor layer and the second semiconductor layer and has a third region and a fourth region, the semiconductor contact layer contacts the first region. The first region includes a second dopant and a third dopant, the second region includes second dopant, and the third region includes third dopant. The semiconductor contact layer has a first thickness greater than 50 ? and smaller than 1000 ?.

Abstract: A computer has different operating systems installed in different peripheral access devices thereof, and an operating system switch device controlled to select one operating system from the peripheral access devices for running, enabling the computer to be selectively operated under one of a set of operating systems.