This innovative dsPIC30F2020-based project showcases an interesting approach for reducing speaker distortion and increasing bass response. A dual-coil speaker driver is implemented in the design, but only one of the coils is connected to the power amplifier. The other coil is used for electromotive feedback.
This is not a new idea, but many do not implement it due to the multitude of factors that have to be counted for the analog signal.
Digital Subwoofer Amplifier with Electromotive Feedback Reduces Distortions:
[Download Project] - [View Project PDF] - [via]
Audio spectrum analyzers have always been cool either in Winamp on your computer, or in a sound system that features it. Now you have the option of building it and including it into your soundsystem. In fact i think it would look very professional if you place it inside a nice case.
The real-time system computes the distribution of the audio signal energy to 20 specific frequency bands and displays it on a 20 × 20 LED display. The PIC30F6012A was choose to control this circuit because of its numerous functions needed in this project.
LED Bar Audio Spectrum Analyzer: [Download Project] - [View Project PDF] - [via]
I say another, because we all know the DIY MP3 Player and the AVR Butterfly MP3 Player. This mp3 player can support up to 4 GB of storage (MMC or SD cards) runs from a single AAA battery and has full user control (volume, track, pause, skip, directory) with a 5-way micro joystick.
Also the LCD has contrast control, you can record voice and the firm-wire is totally upgradeable trough RS232. In fact this DIY MP3 player is the coolest I’ve seen so far and it’s full of tricks.
EchoMp3 Another DIY MP3 Player: [Link]
This decoder is fed by a RDS demodulator IC (or tuner) which has RDDA (data signal) and RDCL (clock signal) outputs.T he microcontroller is an Atmega168 clocked on the external 4.332MHz crystal from the RDS demodulator. The TDA7330B RDS demodulator IC from STMicroelectronics is connected to the Atmega168 with RDDA connected to PD4 (on PORTD) and RDCL to INT0 (PD2).
The tuner module on this card is an FM1216 from Philips. It has an unmodulated MPX FM signal output (AF sound output) which the RDS demodulator needs. This is the same signal which is fed into a stereo decoder to produce stereo sound outputs.
Atmega168 RDS decoder: [Link]
This project was designed and implemented an electronic phone directory which has a built-in automatic dialer. The electronic directory allows user to Dial, Enter, Search and Delete entries. When dialing, the Atmel 8515 microcontroller will generate the Dual Tone Multi Frequency (DTMF) signals corresponding to the phone number being dialed. To avoid building the phone circuit for the dialer, a DTMF decoder was used to detect what number is dialed by the user.
Electronic Phone Directory and DTMF Generator: [Link] - [Via]
