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 EarphoneGBA-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 76-

108MHz 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 www.bestbuy.com www.jameco.com http://www.semiconductors.philips.co

m http://www.users.bigpond.com/cool38

6/tda7000/tda7000.html http://www.microbattery.com/Toshiba

%20Webpages/lithium%20coin%20new.htm

http://www.semiconductors.philips.com/pip/TDA7000.html

SPECIAL THANKS TO

Gene Davison

Professor James Hedrick

Professor Ekram Hassib

QUESTIONS?