Abstract: A solid state electronic power switch selectively controls power delivered to a load such as a fan. A momentary contact control switch is provided which is connected to a switching logic circuit whose output state changes when the control switch is activated. A plurality of power control circuits are connected in parallel with one another and in series with a load across a power source. Each of the power control circuits includes either an SCR or a triac element. A turn-on control circuit is provided connected to the SCR or triac for initial turn-on only when a voltage across the element is small compared to a peak-to-peak voltage across it prior to application of gate voltage. With the system of the invention, the load such as a fan can be operated at various discrete power levels without the associated mechanical and electrical noise problems of previous systems.

Abstract: An FM tuner control circuit contains a digital frequency synthesizing control circuit, digital computer means including a microprocessor, a memory circuit, and a manual control circuit for digitally tuning the tuner to any desired FM station. The memory circuit includes a read-only memory containing programs for the microprocessor and a random-access memory in which a group of predetermined station frequencies can be stored. The control circuit also includes a call letter display circuit, a frequency scale pointer display circuit, a frequency display circuit, a manual tuning circuit, and remote control switches for the manual control circuit.

Abstract: An FM tuner control circuit contains a digital frequency synthesizing control circuit, digital computer means including a microprocessor, a memory circuit, and a manual control circuit for digitally tuning the tuner to any desired FM station. The memory circuit includes a read-only memory containing programs for the microprocessor and a random-access memory in which a group of predetermined station frequencies can be stored. The control circuit also includes a call letter display circuit, a frequency scale pointer display circuit, a frequency display circuit, a manual tuning circuit, and remote control switches for the manual control circuit.