Wireless Earphones Avionne Maurice & Jacqueline Suarez Advisors: Prof. Hassib & Hedrick March 5, 2005

OUTLINE Why Wireless Earphones? Project Description Similar Products Original Project Specifications Actual Project Specifications Components Transmitters Receivers Block Diagram Implementation Results References Questions

WHY WIRELESS EARPHONES? Wanted to develop a device which hasn’t been explored thoroughly in the wireless field Increase our knowledge in wireless and RF (radio frequency) technology Construct a device which would be useful and fun to use

PROJECT DESCRIPTION Wireless earphones are lightweight ear-clip stereo headphones made by Maxell. The earphones will be used in conjunction with a portable audio player. Increased range of listening.

SIMILAR PRODUCTS Built-in FM Radio Transmitter requires no batteries. Earphone receiver runs only on 2 AAA batteries. The right earphone serves as the control center. The left earphone houses the battery compartment. GBA-SP Wireless Earphone

SIMILAR PRODUCTS Headphones work with audio or video devices, like TVs, DVD players, computers, etc. Transmission range about 300 feet. Rechargeable batteries Transmitter is bulky Headphone vs. Earphone Acoustic Research 900MHz Wireless Stereo Headphones

ORIGINAL PROJECT SPECIFICATIONS Suppression of unwanted signals at 45 dB minimum FM modulation Battery Life: 8 hours minimum Receiver: Ear bud size Transmission Range: 300 ft minimum

ACTUAL PROJECT SPECIFICATIONS Suppression of unwanted signals at 40 dB FM modulation Battery Life of Receiver: 25 hours Battery Life of Transmitter: 25 hours Receiver: Ear-clip size Transmission Range: 200 ft

COMPONENTS RF transmitter RF receiver Battery Earphones Antenna

OLD TRANSMITTERS Originally we had 3 different transmitters from which to choose. Each transmitter had a wide supply voltage, long transmission range, and average in cost. RTF3-433 FM RF Transmitter Module Quasi AM/FM RF Transmitter Module TXM-xxx-A/F FM RF Transmitter Module

OLD RECEIVERS Initially there were two receivers to match the three transmitters. Fairly expensive – about $50.00 Dimensions weren’t very small SILRX-xxx-A/F FM SuperHeterodyne Receiver Module QMR1-433 Quasi AM/FM Receiver Module

NEW TRANSMITTER Tunable from MHz Compatible with any audio device, like a CD player or tape deck Uses a BA1404 IC chip Transmission range is 200 feet With 9 V battery, has a battery life of 25 hours Price: $29.95 FMST-100 STEREO TRANSMITTER

NEW RECEIVER Supply voltage range: 2.7 to 10 V Supply current: typical 8 mA Frequency range: 1.5 to 110 MHz Sensitivity: 1.5 mV With 3 V battery, has a battery life of 25 hours Price: $15.95 TDA7000 FM Radio Receiver

BLOCK DIAGRAM IMPLEMENTATION A CD player was used for the input signal. The audio signal was then received by the FMST-100 stereo transmitter. Within the FMST-100 stereo transmitter the signal is amplified and modulated by the BA1404 IC chip. The signal is then transmitted and received using the antennas. Inside the TDA7000 FM Radio Receiver chip, the signal is demodulated and amplified so it can be heard with the wireless earphones.

RESULTS Transmitter is functional Debugging completed for transmitter In the process of debugging receiver

Mount transmitter in box Increase stability of transmitter Design an antenna system

REFRENCES /tda7000.html /tda7000.html Webpages/lithium%20coin%20new.htm Webpages/lithium%20coin%20new.htm /TDA7000.html /TDA7000.html

SPECIAL THANKS TO Gene Davison Professor James Hedrick Professor Ekram Hassib

QUESTIONS?