Background

The transition from the digital to the analog world of circuit design is often marked by a whole class of problems that were once ignored. Suddenly, it is not just a simple "yes" or "no" at the right time but rather a whole slew of questions with a large number of possible choices that each will leave you better off or in an even worse situation. With all the headaches this must invite, what better way to step into the wonderful yet puzzling world of analog than to design and construct something simple and rather entertaining?

A device that detects and displays the amplitude of sound in a given environment would be a good project to take on because the complexity of a basic working unit is relatively simple and, at the same time, provides a few challenges that require a little head scratching. Though the analog portion is very simplistic, the unit will be enhanced a little by utilizing a micro-controller and a touch-sensor to control different display modes for an added "coolness" factor.

Project Report Organization

This project report is split into five different sections with each section being comprised of a number of pages or maybe just one.

• Page 01: Introduction - You are here
• Page 02: Design - Overall View
• Page 03: Design - Conversion
• Page 04: Design - Amplification
• Page 05: Design - Signal Processing
• Page 06: Design - Dimming and User Input
• Page 07: Design - Control and Display
• Page 08: Design - Prototyping
• Page 09: Design - Materials and Layout
• Page 10: Construction - Enclosure and Circuit Board
• Page 11: Construction - Components and Wiring
• Page 12: Evaluation - Pictures
• Page 13: Evaluation - Analysis and Acknowledgments
• Page 14: Information - Schematics, Data sheets, and other items if applicable.

Goals

The following goals were proposed for this project

• Small Form-factor: Rather than going for something that just sits on the table, the audio meter should be small enough to fit in a pocket.
• Battery Operated: The audio meter should operate from batteries such as AAA in order to maintain the small form-factor goal - this means low power consumption as well.
• Cheap: Being simple, portable, and battery operated should automatically make it a good candidate for being cheap. Being a student means cheap is good!

Because the design and construction phases of this project took place while university was in session of Spring 2007, the overall length of time for this project was about 2 months.

Disclaimer

Although all data has been checked over, mistakes are certainly possible during the design and construction phases of this project. Therefore, before attempting to replicate or borrow ideas, it would be wise to verify the information presented herein by oneself or with a 3rd party who has sufficient knowledge of the material. That being stated, you may notice a few mistakes in the construction pictures that will be corrected later on. I have tried my best to point out such mistakes and have you avoid making the same ones yourself.