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Unformatted text preview: Three Band Audio Equalizer Final Project Report Arun Swain (aps97) Yunchi Luo (yl477) The goal of this project was to design, construct and test a three band audio frequency equalizer with variable gain levels for each of the three bands: bass, midrange, and treble. The specifications for this project were to use bandpass or high and low pass filters with rolloffs of 12db/octave outside the passband. Additionally, the gain had to range between +20db and -20db in each passband. We also had to assume a 100 – 200 mV input signal and produce an maximum output of 1V. We first started out by researching on the Internet for traditional frequency ranges for each of the bands and set on using a passband of 20 Hz – 300 Hz for the bass, 200 Hz – 7KHz for the midrange, and 3 KHz – 20 KHz for the treble. We approached the design by choosing to create three separate band circuits and then summing them at the end using a summing amplifier. Also since we needed rolloffs of 12db/octave which are equivalent to 40db/decade it was apparent that we needed to work with two pole filters. We also chose active filters instead of passive filters in our design to minimize noise in our output. In addition to the three band audio amplifier circuit, we also created an LED circuit with 4 LEDs to show visually the volume of the sound R2 24k C2 0.033u R13 10k R8 1k R3 24k LED 1 3 2 4 11 OUT +- V+ V- C1 0.022u R12 1.2M C3 2.2n R10 11.9k R13 10k R14 10k R13 10k R7 R8 1k 1 3 2 4 11 OUT +- V+ V- 1 3 2 4 11 OUT +- V+ V- R5 24k LED R4 10k 1 3 2 4 11 OUT +- V+ V- 1 3 2 4 11 OUT +- V+ V- C3 2.2n R7 1 3 2 4 11 OUT +- V+ V- C2 0.033u 1 3 2 4 11 OUT +- V+ V- R8 1k R8 1k 100k R8 1k R1 24k C3 2.2n R3 24k 100k 1 3 2 4 11 OUT +- V+ V- 1 3 2 4 11 OUT +- V+ V- +12V R6 24k LED 100k...
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This note was uploaded on 03/31/2009 for the course ECE 210 taught by Professor Staff during the Spring '08 term at Cornell.
- Spring '08