741- SIGNAL

Project Assignment: Six-Band Audio LED Visualizer (Complete Implementation)

You are required to fully design, simulate, implement, and document a Six-Band Audio Level Display System based on analog signal processing principles. The final outcome must be accurate, functional, and professionally presented.

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## Objective

Develop a complete system that:

– Accepts an audio input signal

– Splits it into six distinct frequency bands

– Drives six LEDs, each representing a specific frequency range

– Demonstrates correct behavior through simulation and testing

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## System Requirements

### 1. Circuit Design (MANDATORY)

Design a complete and correct circuit that includes:

#### A. Input Stage

– Audio input (Microphone module or AUX input)

– Signal conditioning (biasing and amplification if needed)

#### B. Filter Bank (Core of the system)

Design six active filters using Op-Amps:

| Band | Frequency Range |

|——|—————-|

| A | 0 60 Hz |

| B | 60 250 Hz |

| C | 250 500 Hz |

| D | 500 Hz 1 kHz |

| E | 1 2 kHz |

| F | 2 4 kHz |

– Use band-pass filters

– Clearly calculate and justify all resistor and capacitor values

– Ensure proper separation between bands

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#### C. Detection Stage

– Convert AC signal to DC using:

– Rectifier (Diode-based or Precision Rectifier)

– Smooth the signal using a capacitor

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#### D. Output Stage

– Each band must drive:

– One LED

– With proper current-limiting resistor

– LEDs must respond to signal strength (brightness or ON/OFF)

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## 2. Simulation (VERY IMPORTANT)

You must:

– Use Proteus or Multisim

– Draw the full schematic clearly

– Label all components and values

### REQUIRED:

Record a video showing:

1. Input signal applied (Function Generator)

2. Changing frequency step-by-step:

– 50 Hz

– 100 Hz

– 300 Hz

– 700 Hz

– 1500 Hz

– 3000 Hz

3. Show that:

– Each LED turns ON only at its corresponding band

The video must clearly prove that the circuit works correctly.

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## 3. Testing & Verification

– Use Function Generator for controlled signals

– Use Oscilloscope (DSO) with FFT if available

– Verify:

– Each band responds to correct frequency

– No overlapping errors

– Clean signal behavior

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## 4. Calculations (MANDATORY)

Provide:

– Filter design equations

– Cutoff frequencies

– Component selection justification

– Bode plots (gain vs frequency)

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## 5. Final Report (Professional)

Structure:

### 1. Introduction

– Project idea and purpose

### 2. Design

– Block diagram

– Circuit diagrams

– Explanation of each stage

### 3. Results

– Simulation screenshots

– Tables and graphs

– Observations

### 4. Discussion

– Problems faced

– Solutions applied

– Improvements

### 5. Conclusion

– Final system performance

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## 6. Evidence Required

– Screenshots of simulation

– Circuit diagram

– Video recording of working system

– Optional: Real hardware photos (if implemented)

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## Important Notes

– The circuit must be fully functional and accurate

– Component values must be calculated, not random

– Simulation must clearly demonstrate correct band separation

– Keep the design efficient (minimum components where possible)

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## Final Deliverables

1. Complete circuit design (correct and tested)

2. Simulation file (Proteus/Multisim)

3. Video showing working circuit

4. Full report ( 10 pages)

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## Expectation

The final system must behave as a real audio spectrum visualizer, where each LED accurately represents its assigned frequency band.

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Request to Prepare a Separate Word Document Components and Circuit Implementation

Please prepare a separate Word document that clearly and professionally includes the following:

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### 1. Bill of Materials (Components List)

Create a well-organized table that lists all components used in the circuit, including:

– Component name

– Symbol (if applicable)

– Value (e.g., resistance in ohms, capacitance in farads, etc.)

– Quantity required

Example format:

| Component | Value | Quantity |

|———-|——–|———-|

| Resistor | 10k | 6 |

| Capacitor | 100nF | 6 |

| Op-Amp | LM741 | 3 |

| LED | – | 6 |

| Breadboard | – | 1 |

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### 2. Circuit Implementation (Step-by-Step Procedure)

Provide a clear and concise step-by-step explanation of how to physically build the circuit in the lab. The steps should be practical and easy to follow, such as:

1. Connect the audio input (microphone or audio jack) to the pre-amplifier circuit.

2. Build the op-amp pre-amplifier stage and adjust gain appropriately.

3. Split the signal into six paths using filters (low-pass, band-pass, and high-pass).

4. Connect each filter output to its corresponding amplifier stage (if required).

5. Add a peak detector (or rectifier) circuit for each channel to convert AC signals to DC.

6. Connect each channel output to an LED with a proper current-limiting resistor.

7. Ensure correct power supply connections for all op-amps and components.

8. Test each stage individually before running the full system.

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### 3. Important Notes

– The procedure must be practical and suitable for implementation in a university lab.

– Use clear and simple technical language.

– Diagrams or small sketches can be added if necessary to improve clarity.

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### 4. Purpose of the Document

This document should serve as a practical guide that explains:

– What components are required

– How to build and connect the circuit step by step

So that any user can replicate the system easily in a real lab environment.

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