Abstract: A light actuated switch apparatus is described in which no movable switch contacts are employed. The switch uses a light source and shutter to activate an array of light sensitive devices to generate a binary code that provides the switching function. One embodiment of the switch apparatus is employed inside a control knob providing a binary code generated by shutter action of a light source on an array of phototransistors. Another embodiment employes the above control knob including switch apparatus as well as a second knob and printed board to form a dual switch apparatus. As no switch contacts are employed there is considerable reduction in electrical components. Additionally, this also greatly reduces the space required for mounting the switch, is readily serviceable or replaceable as no parts are located within an instrument, and is less expensive as no contacts eliminate any wear and potential problems associated with movable through stationary contacts.