Geoff Johnson » Electronic

Alpha

Geoff — Sun, 25 Sep 2011 20:37:41 +0000

Alpha is a custom designed bicycle meant to challenge the standard for commuter cycling and lead the way to new innovations within the industry of bike components. It was created for my senior design project with a team of 4 other engineers. We worked for over 2000 hours to design and fabricate Alpha.

The main attributes of the bike are a fully enclosed belt drive system for powering the rear wheel, an electro-mechanical clutch to switch between freewheel and fixed gear riding, and an integrated electronics package which feeds out data to both a handle bar mounted LCD and an SD card.

I was responsible for designing the drive system which includes the SWIFT (Switchable Integrate Free/Fixed Transmission). It took me over 700 hours to design and manufacture the components with the help of one of my team mates. We are now in the process of patenting the SWIFT system and other novel piece of Alpha.

Our team won both the mechanical engineering and all engineering school competitions and was featured on Wired, Core 77, Gizmodo, Engadget and many more! Visit the website for Alpha for more detailed information about its conception, development and future.

SWIFT installed in the custom bottom bracket

Here is the final presentation video given to a team of judges, faculty and students at the all Engineering School Senior Design Competition.

Wireless Variable Wave Speaker

Geoff — Sat, 24 Sep 2011 04:47:44 +0000

I created this wireless speaker for my second mechatronics lab. I designed the enclosure, designed and built the circuitry to drive the cone and wrote the code that accepted the wireless transmission and drove the speaker. There is a microprocessor on the top with a wireless board that receives a signal from a master computer and plays a single frequency for a specified duration. On top of the speaker is a switch to change the waveform of the note between square, triangle and sine; there was a very noticeable difference between the three. Every student in the class built a speaker in either the high, medium or low range of frequencies. We then used the master computer to orchestrate a concert with the 65 speakers, we played Mario.

Isometric View

Wave Form Switch

Aeroelastic Flutter

Geoff — Thu, 22 Sep 2011 23:50:36 +0000

The task of this project was to generate electricity using only wind power and no rotating parts. My team built an apparatus that could hold a tensioned rubber belt which would exhibit the phenomenon of aeroelastic flutter at just 13 miles per hour. The belt would begin to vibrate and by attaching magnets inside copper coils to one end, we were able to generate 0.064 Watts of electricity, which is enough to power a small LED.

You can see the final write up here!