Milen @ instructables.com writes:
The purpose of the project was to create an external USB audio card, which could be able to:
1) serve as usual external USB audio card with headphone/line output and audio line input
2) can transmit the digital audio data at relatively long distance (20m -100m)
3) can receive and process the digital audio data send by the similar card and either transfer it through the USB to the PC, or convert it to analog audio signal
As long distance transfer media was chosen the POF.
A short explanation of the POF technology will be presented:
External USB audio card with optical S/PDIF POF interface - [Link]
Occupying a footprint of just 2.57×3.24 mm, the STA333IS single-chip digital audio system from STMicroelectronics furnishes up to 20 W of audio output power for use in space-constrained LCD and LED televisions, docking stations, and digital wireless speaker systems. With is wide operating voltage range of 4.5 V to 18 V, the device is also suitable for battery-operated equipment.
Part of ST’s SoundTerminal family, the STA333IS combines digital audio IP, such as FFX full flexible amplification, along with signal processing and power circuitry in a chip-scale package to create a high-power, single-chip solution for all-digital amplification. Its power section consists of four independent half-bridge stages. Two channels can be provided by two full bridges capable of delivering up to 10 W + 10 W of power.
Tiny digital audio SoC delivers up to 20 W - [Link]
Boris Landoni @ open-electronics.org writes:
Today we present you a stereo 10 + 10 Watts audio amplifier based on TDA7297SA, a monolithic dual bridge amplifier that is suitable to be used in projects that feature access to a single 12 volts power supply.This is a compact stereo amplifier: its field of application range from car stereo to portable audiovisual equipments (eg: for sport or public events, conferences or even emergency protection and safety mission equipements such as those needed after distaster events)The heart of the amplifier is the TDA7297SA integrated from STMicroelectronics, a monolithic dual bridge amplifier capable of delivering, in fact, 10 + 10 watts.
A versatile, powerful 10 + 10 W Audio amplifier - [Link]
O’K, after having some fun with stereo version of the VU meter I described in my previous blog-post, now it’s time to do a serious stuff. Studio grade VU meter !!! 24 steps, equally spaced every 3 dB, covering Extra wide Dynamic Range from -63 up to +6 dB. Single (mono) channel this time, no messing around, absolute precision at the stake. Plus, it keeps absolutely Top-Flat linear frequency response from 40 Hz up to 20 kHz(*).
Audio VU meter with extra wide Dynamic Range 69 dB - [Link]
Texas Instruments has introduced three analog-input class-D stereo amplifiers for use in soundbars, after-market automotive solutions, portable audio docks, and LCD televisions. The TPA3116D2, TPA3118D2 and TPA3130D2 feature the industry’s highest programmable switching rate and widest power supply range, enabling audio output that is both high quality and highly efficient. The devices are pin-to-pin and software compatible and can support a single-layer printed circuit board (PCB), enabling cost savings by allowing designers to reuse a single layout for multiple designs. [via]
Class-D Audio Amplifiers with Wide Supply Range and High Switching Rates - [Link]
Vinod.S @ blog.vinu.co.in writes:
This is my first AVR based hobby project and the most successful one compared to my all previous stuff. I am 100% satisfied with this work.. Few months ago, I tried to make a wav player using a PIC16F877A. It worked anyway, but the audio quality was not so good for higher sampling rate because that chip doens’t have enough ram and thus I couldn’t implement a good data buffer. But when I bought an atmega32 microcontroller, the first thing came to my mind is to make a good wav player…Now, I have completed my work and the audio quality is really amazing…
NOW I can say that, my wav player IS ABLE TO PLAY 8 BIT MONO/STEREO with maximum bitrate of 1300kbps for mono and 1600kbps for stereo … ie it can play an 8 bit mono wav of sampling frequency upto 160KHz and stereo upto 96KHz without any noise or trouble!!!!! (at OSC 16.450MHz).
Stereo MMC WAV player using ATMEGA32 - [Link]
In this article I will discuss my own experiences about designing a USB sound card, which is the USBDAC. DAC is an acronym for Digital-to-Analog Converter because in a sound card, digital data representing the sound is converted into analog voltage that moves the speaker cone.
My device is loosely based on the PCM2706 reference design. I will not go through the tecnical details but instead concentrate on my own experiences in the design of the device. This is to keep people not familiar with electronics, as well as newcomers to electronics design, interested. You will see that one working product is the result of many failed prototypes.
Designing a USB sound card - [Link]
Amplifier with TDA7294 of the ST microelectronics, you can get power up to 100W in a single chip.
TDA7294 Power Audio Amplifier 80W - [Link]
SweepGen turns a PC into an Audio Oscillator and Sweep Generator which can be used for testing audio or educational purposes. In conjunction with audio test instruments, you can make frequency response plots. SweepGen uses the sound card in your PC to produce sine waves that are mathematically correct almost to CD quality, indeed it’s more likely that the quality of your PC sound card will be the limiting factor rather than the code in SweepGen.
SweepGen – Turn your PC into an Audio Oscillator - [Link]
This circuit is a complete 2.1 amplifier for two satellite speakers and one subwoofer.
TDA2030 Audio Amplifier with 2.1 – 3 x 18 Watt – Subwoofer - [Link]