By: Devon Schmidt & Kyle Da Rif Instructor: Stanislaw Legowski Senior Design 2012/2013

 An electronic device which analyzes an input stereo audio signal and turns LED arrays on and off based upon the frequency information of the input signal in real time.  Generally used in professional lighting and music applications ◦ Concerts ◦ Parties ◦ Sporting or other major events

 Receives an input in the form of a stereo signal from source ◦ MP3 Player, iPod, Smart-Phone, etc.  Filters frequency information of signal into set number of bands ◦ Information is separated by active analog filters  Filtered information is output to LED arrays associated with each band.  LEDs will now illuminate when input frequency information falls within the band connected to those LEDs.

 Master / Slave chip configuration with integrated speakers. ◦ Master filters information to Slaves which drive the LEDs  Input stereo signal is sent to the Master chip and an amplifier for each speaker  Master is programmed to filter signal into 8 frequency bands per channel  Two bands are then assigned to each Slave chip.  16 LEDs assigned to each band  256 Total LEDs

 Couldn’t find a way to have the Master and Slaves communicate  SPI bus (Serial Peripheral Interface) ◦ As the name states the information is output in a serial fashion ◦ Required a Parallel output to update the Slaves at once  Otherwise LEDs would lag behind the audio signal  Had to restructure project to an analog format

 Replaced Master chip and individual speaker amplifiers with a single amplifier and a filter bank using HPFs, LPFs, and BPFs  Replaced Slaves with RMS to DC Converters, PWMs, and LED Drivers  Reduced the number of LEDs per band to 4  LED Total: 64

 The amplifier receives the input stereo signal and outputs an amplified signal to both speakers and the filter bank.  Filter bank separates frequency information of the input into 8 bands per channel  In each band, a RMS to DC converter modifies the AC waveform into a true RMS signal  PWM uses RMS signal to control duty cycle of output waveform  LED Driver utilizes duty cycle signal to illuminate LEDs associated with specific band

 1 Texas Instruments TPA3100D2 Class-D Amplifier Evaluation Board  2 Polk Audio 4Ω-Load Speakers  Filter bank ◦ 28 Analog Devices OP177 Operational Amplifiers  16 Analog Devices AD736 True RMS-to-DC Converters  16 Linear Technology LTC Voltage-Controlled Pulse Width Modulators  16 Diodes Inc. AL5802 Adjustable Current Sink LED Drivers  16 Texas Instruments LM741 Operational Amplifiers  16 Vishay Siliconix IRF530PBF-ND N-Channel MOSFETs ◦ Required for Dimming Effect in LED Drivers  16 Texas Instruments LM7805CT 5 Volt Voltage Regulators ◦ Required for RMS to DC Converter and PWMs

 15W/channel given a 4Ω-Load and 12V supply  Highly efficient Class-D structure  Left and Right channel outputs  Utilizes stereo RCA input ◦ Converted to 3.5mm “headphone jack” to allow a wider range of source devices

 Polk Audio DB461 ◦ 4” x 6” Speaker ◦ 4Ω-Load Impeadence ◦ 120 Watt Peak Power ◦ 40 Watt RMS Power ◦ 75Hz – 22kHz Frequency Response Polk Audio DB461 4” x 6” Speaker, Photo, n.d., Web, April 25,

 Wanted to keep as much frequency information as possible  Final Bank Structure (1 Channel) ◦ LPF at lowest frequency (31.25 Hz) ◦ 6 BPFs at intermediate frequencies ◦ HPF at highest frequency (≥4k Hz)  Total number of filters for both channels: 16

 Filter center and limit frequencies found using table  Three Considered Filter Configurations ◦ Second order HPF ◦ Second order LPF ◦ Fourth order BPF Octave Bands Band #f_low (Hz)f_ctr(Hz)f_hi (Hz)%BW "Center Frequencies and High/Low Frequency Limits for Octave Bands, 1/2- and 1/3-Octave Bands." N.p., n.d. Web. 25 Apr

 2 nd Order Active-HPF  All capacitors assumed C = 0.1µF  2 nd Order Active-LPF  All resistor assumed R = 10kΩ

 General purpose operation amplifier  12V operating voltage  Used for simple amplification and inverting LM741 Operational Amplifier, Photo, n.d., PG_LI- g86xQ/UHBAryRVeSI/AAAAAAAAAbY/apbM8MjOwws/s1600/lm741.jpg, Web, April 25, PG_LI- g86xQ/UHBAryRVeSI/AAAAAAAAAbY/apbM8MjOwws/s1600/lm741.jpg

 Uses 12V input to provide 5V output  Utilized as simple solution to provide 5V to circuit  Well-Protected ◦ Internal current- limiting ◦ Thermal Shutdown 7805CT 5V Regulator, Photo, n.d., Web, April 25,

 Wide voltage range ◦ +2.8V, -3.2V ± 16.5V  Uses ±5V source to match PWM  High Accuracy ◦ Total Error: ±0.3mV ± 0.3% of signal  Standard DIP 8 Package ◦ Easy for breadboard testing  Low Supply Current ◦ 200µA AD736 RMS-to-DC Converter, Photo, n.d., AD736AQ.jpg, April 26, AD736AQ.jpg

 Highly Flexible ◦ Programmable Oscillator frequency and frequency divider  Low Operating Voltage ◦ 2.25V – 5.5V  Required Voltage Regulator  Small Size ◦ Required Break-Out Board for testing LTC PWM Generator, Photo, n.d., April 26,

 N-channel enhancement MOSFET  Fast switching ◦ Allows LED driver to utilize PMW signal IRF530 N-EMOSFET, jpeg, n.d., Web, April 25,

 Utilizes N-Channel MOSFET for LED Dimming ◦ PWM Signal applied to MOSFET  MOSFET output signal received at the Enable Pin (Pin 3)  Simple Construction ◦ 2 NPN Transistors  Q1 measures current using an external resistor  Q2 regulates current  0.8V to 30V operating voltage  Driving current 20mA to 100mA AL5802 LED Driver, Photo, n.d., circuits-images.dz863.com/114/AL5802.jpg, April 26, 2013http://pinout- circuits-images.dz863.com/114/AL5802.jpg