Design Project #3

(Last Modified: 04 November 2010 06:11:45 PM )

ECE 3220 Home Page

AUDIO AMPLIFIER EQUALIZER CHANNEL

Input Signal Source: (Function generator in the lab and/or earphone jack from portable CD player)

• Frequency Range: 20 Hz to 20 kHz
• Amplitude: Peak Voltage Varies. Typically 1.0V peak-to-peak
• Output Impedance: 50 ohms (function generator)

Input Specifications:

• Input Impedance: Your choice, but not less than 600 ohms
• Coupling: AC
• Frequency Response: Per your team's assigned Frequency Band

Gain Specifications:

• Midband Gain: 10 (when driven by 50 ohm source)

Output Specifications:

• Load: 32 ohms (standard headphone impedance).
• Power: 100mW maximum

Available Power Supply:

• Supply Voltage: +/- 0VDC to 36VDC  (You set the voltage you need)
• Current Capability: 1A

Presentation:

Equipment Available:

• Power Supply
• Oscilloscope
• Function Generator
• Portable CD player
• Powered Computer Speakers
• The computer and projector in Room 101.

Your group will have a total of 30 minutes. Time limits will be strictly enforced - we have the room for a total of 2.5 hours. You may not be able to "take the stage" until your 30 minutes starts (so you may have to do some set-up) while you must be completely "off the stage" prior to the end of your 30 minutes. You should allow approximately 5 minutes for questions as part of your presentation.

A good way to deal with this is to utilize your team effectively. Have your introductory material such that it does not depend on anything being set up. While the introductory material is being presented, the other team members can be getting the Powerpoint presentation up (if you use one) and any equipment set up. Likewise, perform any demonstrations in the middle of your presentation so that, as someone is making concluding remarks that, again, do not rely on any props or projected images, the other team members can be taking down your set-up so that you can walk off stage promptly when finished. PRACTICE your presentation to be sure you have enough time for everything - you will have to control how much detail you go into rather carefully.

Each person in your group is expected to materially participate in the presentation. Material participation means something beyond being the person that introduces everyone else and twiddles the knobs on the function generator. Each person should present enough technical material as to be able to demonstrate a solid working knowledge of the overall project and strong  knowledge of at least some technical aspect of it.

Your presentation should cover the following areas:

• Your circuit - including basic operation, biasing and what component(s) dictate the midband gain and the upper and lower cutoff frequencies..
• Your design process - why you chose the basic circuit you did and how you went about meeting each of the performance specifications.
• How and why you chose the specific component values that you did.
• Verification that each of the design specifications was met.
• A demonstration of your circuit that shows, at least approximately, where the edges of the passband are and what the gain is within the passband.

Because of the tight time limit and because everyone in the class is working on the same project, you do not need to spend any length of time discussing the goals and objectives and specifications of the project - everyone knows what they are. One way to think of this is to assume that you are making a presentation that is part of a much larger presentation. The "big" presentation is for the entire audio equalizer and the initial presentation was made by someone that thoroughly covered the project goals and specifications and discussed how the equalizer what broken down into a number of channels. They then turned the presentation over to your team to discuss one of those channels.