NoiseCanceling Headphones

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Noise-Canceling Headphones

• David Ringle
• Engr311A Personal Project

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Additional 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 Aids

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How Noise Cancellation Works

• Wave Addition

Destructive Interference


Constructive Interference


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Circuit Design
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Cadence Implementation
Inputs, Output Power
Potentiometers

• Aux Input was modeled as a large resistance in
  testing of the primary circuit

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Inverting (Out-of-Phase)
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Non-Inverting (In-Phase)
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Inverting w/ Aux Input
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Physical 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 solution?