Dex Alpiche was born and raised on the island of Hawaii where he grew up near the town of Paauilo. He is a drummer who enjoys volleyball, baseball, surfing, swimming, ATV and dirt bike trail riding. In 2005, Dex graduated with an A.S. degree in Electronics Technology from Hawaii Community College. He is currently pursuing a degree in the Electricity Program at H.C.C. and expects to graduate in 2008. Dex also works for Subaru Telescope National Astronomical Observatory of Japan as a student of the electronics technician group.
Home Island: Big Island
Institution when accepted: Hawaii Community College
Akamai Project: Acoustic Noise Canceling System
Project Site: Academia Sinica Institute of Astronomy and Astrophysics
Mentor: Derek Kubo
Located up on Mauna Kea’s slopes is SMA’s maintenance facility where there is a telephone which is fairly close to an EMI (electro-magnetic interference) filter. This EMI filter produces a distinctive acoustic sound which interferes with communication. My goal in this project was to produce a replica of this acoustic sound and cancel it out with a circuit. This circuit is composed of a transformer, full bridge rectifier, buffer, active filter, power amp, power supply and a subwoofer. I took tests using an oscilloscope and found out that the transformer was producing a clean 120Hz sine wave, as compared to 60Hz that normally comes out from your 120v ac outlet. I have produced a circuit that can replicate and cancel out the 120Hz sound. The design of the circuit, measurements of the EMI filter with the circuit and without the circuit will be presented. The 120Hz sound can be canceled out by producing the same frequency and inverting the sine wave.