Special equipments ( 4 ) :

• Burwen TNE7000 Transient Noise Eliminator - Schematics and Lineup Instructions   
• Burwen DNF1201A Dynamic Noise Filter - Schematics and Lineup Instructions   
• Infrared Head Phones - Using this low-cost project one can reproduce audio from TV without disturbing others. In place of a pair of wires, it uses invisible infrared light to transmit audio signals from TV to headphones.   
• Laser Link Communicator - audio transmission up to few hundred meters   

Design ideas ( 35 ) :

• A Better Volume Control - use linear potentiometer and one tran resistor to make almost logarithmic response curve   
• Amplifier Thermal Protection and Shutdown Circuit   
• Amplifier Timer - Turns-off your amplifier when idle for 15 minutes, fed by amplifier tape-output
• Ask the Applications Engineer - a collection of articles from its "Analog Dialog" newsletter in pdf format from   
• Audio Auto Shutoff - purpose of this circuit is to automatically turn off any device plugged into its power outlets after a certain period of time of silence   
• Circuit combines power supply and audio amplifier - This circuit can helpful if you must transfer dc power and audio over a pair of copper wires. The circuit uses only one IC, the well-known LM317, a low-cost power-supply regulator. Using this chip, you can modulate the adjustment-pin input with the audio signal from an electret condenser microphone, connected between the output and the adjustment terminals of the IC.   
• Class A Amplifier Design   
• Class D audio-power amplifiers: Interactive simulations assess device and filter performance - Class D amplifiers are much more efficient than other classical amplifiers, but their high efficiency comes at the expense of increased noise and distortion. You can assess the frequency- and time-domain characteristics of a Class D amplifier, including the output filter, using online simulations.   
• Class-T Digital Audio Amplifier Evaluation Board using Digital Power Processing Technology EB-TA2020 from Tripath Technology - This application note describes a diigtal amplifier which operates from 13.5V power source and outputs up to 20W por channel power. The application note is in pdf format.   
• Designing With Opamps - Audio design has for many years relied on a very small number of opamp types. The TL072 and the 5532, numbers that will be immediately familiar to anyone involved in audio electronics, have dominated the small-signal scene for many years. There are however other opamps, some of which can be very useful, and a selected range is covered here.
• EDN ears-on project: Listening to Class D - You needn't look further than Class D audio amplifiers to find a technology whose proponents tend toward exuberant advocacy at best and bald-faced hype at worst. Although these ICs are not yet the be all and end all of audio amplification that their makers would have you believe, they are remarkably good-certainly more listenable than the clamor about them.   
• George Krilov audio schematics page - page is about transistor audio power amplifiers, contains articles about power amplifiers shematics, design, construction and SPICE simulation, page is partially in English and partially in Russian   
• Guitar Effects FAQ   
• Jensen Transformers Application Schematics - many practical circuit ideas using audio transformers   
• Load Sensing Automatic Switch - apply power to the entire audio system by turning on one item, simple circuit   
• Loudspeaker Protection and Muting - information and circuits   
• Main principles of amplifier wiring - how to wire operational amplifier circuits   
• Mixed feedback drive circuits dor audio output transformers - using feedback eliminates transformer distortion and primary resistance   
• Mosfet Power Amplifiers - A discussion of the benefits of the lateral Mosfet output devices used in todays High Power audio amplifiers   
• NE555 drives a speakes: Pulse Width Modulation Amplifier   
• Optocoupler Application Guide - Resistive optocouplers, comprising a LED coupled to a photoresistor, have some unique advantages as control elements in analog audio circuits.   
• Philips SAA1099 Sound Generator   
• Proper Grounding Inside Equipment Avoids Ground Noise Coupling (aka"Pin 1 Problems") - 15KB PD   
• Pushing the Limits of Audio Power Amplifiers   
• Removing the "DC Thump" from Audio Circuits   
• Signal Detecting Auto Power-On Unit - switches on relay when detects sound input   
• Sheldon's Audio Designs - audio DACs and tube amplifiers   
• Simplest Ever Amplifier Bridging - a design for a simple add-on bridging adapter for stereo power amplifiers   
• Simulation Electronique SPICE - some hifi circuits and simulation of them using SPICE, text in French   
• Soft-Start Circuit For Power Amps - redusces the current spike large transformers take when switched on   
• Subtleties count in wide-dynamic-range analog interfaces - transporting high-dynamic-range analog signals from one piece of equipment to another is not a trivial task, this article gives some help to it   
• The ALTMANN "SPLIF" Amplifier Topology - something about how to get some of the feedback out of our HIFI amplifiers   
• Thermo-Fan To Keep Your Amp Cool - fan controller which controls fan based on temperature
• Using Current Sources, Sinks & Mirrors In Audio - Integral to most audio amplification systems, the current source and current sink are indispensable.   
• Variable Amplifier Impedance - idea of being able to vary the output impedance of a power amplifier   

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