A check valve actuator has a body, a sliding seat, a drive shaft, a spring assembly and a knob. The semiconductor light emitting device includes a light emitting unit, first and second conductive members, a sealing member, and an optical layer. If the appliance is activated by a fixed code activation signal, a fixed code word is used to generate and transmit each of a sequence of different fixed code activation signals until the user indicates a successful transmission. The design tool also can determine, based on the indicated component and on the input gated clock waveform, an output sequence of signal transition representations derived from the input sequence of signal transition.