Noise-Canceling HeadphonesAdditional FeaturesHow Noise Cancellation WorksCircuit DesignCadence ImplementationInverting (Out-of-Phase)Non-Inverting (In-Phase)Inverting w/ Aux InputPhysical ImplementationNoise-Canceling HeadphonesNoise-Canceling HeadphonesDavid RingleEngr311A Personal ProjectAdditional Features•Can mix in a line-level input–CD / DVD Player–Dictaphone•Can switch from Out-of-Phase to In-Phase–‘Stethoscope’-like Audio Probe–Directional Microphones–Hearing AidsHow Noise Cancellation Works•Wave Addition+ =+ =Destructive InterferenceConstructive InterferenceCircuit DesignInputs, Output & Power•Aux Input was modeled as a large resistance in testing of the primary circuitPotentiometersCadence ImplementationInverting (Out-of-Phase)Non-Inverting (In-Phase)Inverting w/ Aux InputPhysical Implementation•Used Audio-Taper instead of Linear-Taper Pots–Should be no drawbacks–Radio Shack only carried audio–Cheaper than online equivalents•Used UA741 OpAmps instead of NE5532 ICs–Documentation was wrong on the original circuit!–Slew rate should not be a problem–Current may be an issue•Transistor
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