1. Tangible Electricity: Audio Amplifier and Speaker
John Miller, Brandon Herrera
Baylor University
Self introduction
Goal for this presentation: present an example project that might spark your own ideas
Welcome feedback

2. Course Overview First-semester students for all majors
Per section: 32 students, 1 TA
Introduction to Engineering
Want to do?
Practice
Useful tools/skills
Broad content
Motivation
Is this something they want to do?
What’s involved in the practice of engineering? What’s it like? Design process, teamwork, communication
Fundamental skills and tools – units conversions, Excel
Content from both ME and EE
Motivate them for future learning

3. Project Criteria A project needs to: Not involve programming Be cheap
Pique their curiosity, make them ask how it works. Being open-ended is part of that.
Be simple and manageable both for the students and instructors! Work within time and space constraints.
Be fun so they are engaged
Be something they can take home and show off in order to establish that identity
Be an application of theory that we’re discussing

4. Project Overview Two parts: Individual 3 lab sessions, 75 min each
Solder & test amplifier
Build speaker
Individual
3 lab sessions, 75 min each
Amplifier soldering
Amplifier testing and start speaker
Speaker testing

5. Amplifier Design Done by faculty Small – 1x2 in
12 components – 6 thru-hole, 6 SMD

6. Week 1: Soldering First time for most Watch 2 videos (YouTube)
“Reading” assignment
Regular classroom
Worked in pairs (1 iron per 2 students)
TA evening “lab hours”
See Lab 1 assignment
Had TA’s hold evening lab hours

7. Supplies Components Safety Tools Regular classroom, brought in:
Power strips
Soldering kits with iron, pliers, tweezers
Provide components & PCBs
Safety equipment (mats and glasses)

8. Week 2: Amplifier Testing
Tested for operation with commercial speaker
Help them troubleshoot
Start working on speakers

9. Week 3: Speaker Testing Provided magnets and coils of wire
Otherwise household materials
Lots of examples (YouTube)
Bring completed speaker to lab

10. Student Examples

11. Testing Procedure DC supply MATLAB script
Eliminate difference in batteries
Measure power (V&I) to get sensitivity
MATLAB script
Sensitivity = efficiency
Played tones and recorded microphone
FFT of that
2 tests:
Fixed-frequency tone test to determine sensitivity
Sweep to get average SPL in 3 frequency regions (low, mid, hi) and overall

12. Student Feedback Positive student comments: Enjoyed learning to solder
Surprised at the simplicity of a speaker
Overcoming failure or improving performance by iterating their design
Seeing a wide variety of solutions to the same problem
Experiencing the technical evaluation of a prototype
Accessibility of simple construction materials
We gave the following post-assignment:
Write a short (1-2 page) report that contains the following:
Two paragraphs summarizing your experience with the lab. Write about what you learned, things you did that worked well, things you would have changed or done differently, etc... Also provide some comments on the lab itself (if there are ways to improve the lab or things that were good and shouldn't change).
Picture of your speaker without the enclosure or a view inside of it
Picture of your speaker and enclosure (i.e. the outside)
Table of measurement data.
Of those who took survey (44%), 88% said “Yes” or “Very much” to enjoying EE activities and 89% said the same to the activities helping them better understand EE.

13. Cost One-time = $5-50 per student Recurring = $10-20 per student
Tools (irons, pliers, tweezers, mats, etc.)
Test equip (mics, mixer, PSU)
Recurring = $10-20 per student
Electrical components
PCBs
Magnets & wire
For us, both were $10/student

14. Lessons Learned Hot glue is great! Magnet wire can tangle
Need more lab time
Speaker testing became repetitive
Questions?