LM4780 Micro-Amplifier Mark designed a very nice micro-amplifier based on LM4780 IC which is a 60W stereo power amplifier. His design consists of two boxes. One for the main amplifier and another for the power supply. He also included a thermal shutdown feature. Complete schematics and design photos can be found on his site below. RC4560-based headphone amplifier This SMD op-amp project uses the TI RC-4560 dual op-amp chip and a salt water-etched PCB. The builder got the op-amp as a free sample from Texas Instruments and scavenged all of the SMD resistors from old hard drive electronics. The results are not pretty, but they’re functional. The circuit used (with some changes) is the Chu Moy design found here. The CMoy circuit is not SMD. Active Bass & Tremble Controller ACTIVE BASS TONE CONTROLLER circuit diagram AVR Sound Effects Processor This project devised by two Cornell students in 2003,they wrote: For this endeavour, we first built an input stage that will amplify the input signal, as well as bias it to 2.5V (since the ADC can only sample positive signals). The ADC (MAX1111) is controlled by the microprocessor (Mega 32) using the SPI interface which was much easier than manually configuring a port to interface with the ADC(believe me, we tried that). We set the Mega 32 to sample the input at about 12 KHz which is fast enough to meet the Nyquist requirement for analog to digital sampling. The digital effects were done using by manipulating the input (which will be discussed in the Design page) and the output is passed to a R-2R DAC to a output amplifier stage and finally, to the speaker. [via] Rundfunker - WLAN mp3 player The Rundfunker is a tabletop mp3 player that scans the WLAN for local audio sources and is able to play shared audio-files. It has a built-in 2-way speaker system, a LC display and a very simple yet powerful user interface. The device is independent of any external peripheral equipment - all hardware components are integrated into the appealingly designed housing including an exclusive aluminium front panel. All you need is 12 V DC power supplied e.g. by a mains adapter. Build These Noise-Canceling Headphones In today’s hectic and noisy world, we are all searching for a little peace and quiet. Well, you might not be able to slip off to a tranquil forest for an hour or two, but you can block out background noise with the Noise-Canceling Headphones . The theory behind this project is that by picking up ambient sound with a microphone and reproducing it out of phase, we can actively cancel or “null” out background noise. In fact, several commercially available devices perform the same function. However, by building your own headset, you can add features not otherwise available and have fun while doing it! Multifunctional alarm clock with internet connectivity We continue to go through circuitcellar 2007 16-bit PIC design contest. Next project (second place winner), developed by DJ Delorie, is a cool multifunctional alarm clock that is connected to internet. Along with cool look of this clock it also has several nice features like automatic time setting on power up, can play streaming MP3 music and of course clock can be remotely managed from personal computer that is connected to internet. Alarm clock runs on PIC24FJ64 microcontroller. Internet connectivity is made through ENC28J60 IC. Clock also is equipped with graphical display, volume control and seven buttons for local control. Full project files are here. Fostex FE167E Bass Reflex Speakers he very first pair of speakers I put together some thirty-eight years ago was a pair of single-driver loudspeakers using 8” Kaltro twin cone drivers. As I type this, I find myself once again listening to speakers using a single full-range driver. This time it is the 6.5” Fostex FE167E fullrange driver. I had recently completed a small low wattage 6T9 valve amplifier, and asked Gio for some suggestions on speakers to match the amp. He suggested the Fostex FE167E. When I saw they were 94dB efficient I ordered them instantly. Packaged with the drivers were two enclosure plans - a floor-standing unit as well as a bookshelf enclosure. I opted for the smaller bookshelf speaker box. The Fostex Recommended Standard Bass Reflex Type Enclosure is 15L with a 50 by 50 mm port that can exit from the front or rear. Audio VU meter 9 leds 5 LED VU Meter kit is based on LB1409 IC from SANYO, which will indicates the volume level of the audio signal it senses * SUPPLY 12V DC @ 50mA * PR1 REF SET * PR2 AUDIO LEVEL SET DIY 6T9 Tube / Valve Amplifier Project A small and simple tube amplifier project using one 6T9 vacuum tube per channel. A single PCB makes this a simple project even for beginners. The enclosure is a low cost baking pan. |
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