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Amplifiers: Audio Circuits
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Audio Amplifiers:   #'s       A - D        E - M        N - R      S - U     
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Last Updated: November 30, 2017 10:27 AM

Circuits Designed by Dave Johnson, P.E. :
Improve the quality of standard TV images  -  I designed this circuit many years ago, based on the claims that the technique would improve the quality of standard TV images.  The circuit adds information to the edges of the objects and was reported to bring out more detail.  After building and testing . . . Hobby Circuit designed by David A. Johnson P.E.-July 08, 2000

Infrared TV/VCR Remote Booster  -  This circuit will boost the signal from any infrared TV or VCR remote, extending the range by a factor of 3X.   . . . Circuit by Dave Johnson P.E.-October 05, 2005

IR TV/VCR Remote Booster  -  This circuit will boost the signal from any infrared TV or VCR remote, extending the range by a factor of 3X.   . . . Hobby Circuit designed by David Johnson P.E.-October 05, 2005

Low Pass Filter, 3Khz, with an Audio Amp  -  This circuit uses a switched capacitor filter IC from National Semiconductor to filter signals with frequencies higher than the 3KHz needed for voice audio.  The schematic includes an audio amplifier that is designed to drive a standard audio head phone . . . Hobby Circuit designed by Dave Johnson P.E.-June 04, 2000

Microphone On/Off Switch Circuit is Pop Free  -  This circuit uses a simple technique to eliminate the usual “pop” sound when an electret type microphone is switched on or off.  The circuit is completely passive and will work on dynamic and electret type microphones . . . Hobby Circuit designed by Dave Johnson P.E.-February 15, 2002


Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:


Headphone MOSFET Amplifier -  Schematic only __ Designed by va3iul

Hi-Fi Headphone Amp -  The intention is to permanently insert the headphone amp between pre and power amps, although it can be used as a stand-alone item.  The input relay is operated by auxiliary contacts on the headphone sockets through a transistor driver (with a small delay) so as to mute the power amp input when listening on headphones __ Designed by Rod Elliott  ESP

Hi-Fi Headphone Amplifier -  The intention is to permanently insert the headphone amp between pre and power amps, although it can be used as a stand-alone item.  The input relay is operated by auxiliary contacts on the headphone sockets through a transistor driver (with a small delay) so as to mute the power amp input when listening on headphones. __ Designed by Richard Crowley

Hi-Fi Headphone Amplifier -  Can be directly connected to CD players, tuners and tape recorders.  * Tested with several headphone models of different impedance: 32, 100, 245, 300, 600 & 2000 Ohm.  * Old 8 Ohm impedance headphones can be also driven, but these obsolete devices are not recommended.  * Schematic shows left channel and power supply (common to both channels).  * Numbers in parentheses show IC1 right channel pin connections.  * A correct grounding is very important to eliminate hum and ground loops.  Connect to the same point the ground sides of J1, P1, C2, C3 & C4.  Then connect separately the input and output grounds to the power supply ground. __ Designed by Richard Crowley

Hi-Fi PC Speaker SystE - M -  Standard LED VU meter, includes simple rectifier circuit for full wave detection __ Designed by Rod Elliott  ESP

Hi-Fi Preamp -  Another preamp, but this one has tone controls, and all pots are PCB mounted __ Designed by Rod Elliott  ESP

High Gain and Fidelity Audio Amplifier -  Here's a general-purpose 2 watt audio amplifier with excellent overall performance.  It is easily configured to serve as an audio output stage for lower power applications or as a more powerful amplifier for room-filling volume.  I've even tried it as an electric guitar "practice" amplifier and with a good speaker it's just about the right power. __ Contact: Charles Wenzel of Wenzel Associates, Inc.

High Performance Analog MEMS Microphone's Simple Circuit Interface to SigmaDSP Audio Codec  -  From this point, follow the documentation for the EVAL-ADAU1761Z regarding software installation, setup, and operation of the system.  The SigmaStudio software is used to program and tune the registers and SigmaDSP core in the ADAU1761 __ Analog Devices from the Lab

High Performance Digital MEMS Microphone Standard Digital Audio Interface to Blackfin DSP  -  These boards are designed to work together and include code to enable the digital audio connection __ Analog Devices from the Lab

High quality exponential VCA -  An audiophile quality preamp, with full switching and programmable gain 

High Quality Sound Mixer -  This project is probably the most ambitious so far, and can be expected to be very expensive.  On the positive side, it is also capable of excellent performance, and can be tailored to suit your exact specifications.  There are several different input modules in the series, the first being the microphone and line input.   The project is presented in parts, and Part 1 shows the mic/line module and has some background information on noise measurements and the general philosophy behind the project. __ Designed by Rod Elliott  ESP

High-End Audio Volume Control Attenuator with IR Control -  The circuit provides both audio volume and input channel selection.  A stepwise volume control is implemented with a set of small relays and resistors.  In a high-end audio system, a noticable sound improvement over potentiomeneters can be obtained, also over 'audio grade' potentiometers.  Clearly, the IR remote control provides convenience over solutions with stepped attenuator rotary switches.  The sealed relays will maintain contact quality over a practically endless lifetime.  

High-Gain Audio Amplifier for Headphones-W7ZOI -  Schematic only __ Designed by va3iul

High-Performance Microphone Preamplifier -  Some recording devices, especially computer sound cards, have poor sound quality or insufficient gain when used with certain microphones.  This tiny module provides a line level output from an unbalanced or balanced microphone and has very low noise and distortion.  It runs off 5-20V DC, consuming just 6mA. __ SiliconChip

Home Brew a Condenser Mike -  Electret condenser microphones have truly come of age in recent years.  No longer are they as temperature sensitive as in the past and they have found their way into many modern amateur transceivers.  An inexpensive condenser microphone with excellent performance can be easily constructed with easily available parts __ Designed by Radio Amateur Society of Norwich

Homebuilt MP3 Player -  Welcome to Frank’s website, home of the do-it-yourself MP3 player, a DDS based signal generator, and more.  For the MP3 player pages, including source code & schematics, please click on the photo below.  Or use the menu on the left. __ Designed by © © 2014 Frank Van Hooft

Improve the quality of standard TV images -  I designed this circuit many years ago, based on the claims that the technique would improve the quality of standard TV images.  The circuit adds information to the edges of the objects and was reported to bring out more detail.  After building and testing . . . Hobby Circuit designed by David A. Johnson P.E.-July, 2000

Improved PL tone Decoder -  A significant amount of interest has been generated since my last article on a PL tone board.  Because of this interest I decided to improve on the old PL tone design.  Figure 1 is an inexpensive PL tone generator with significantly improved performance.  It has a much more stable tone frequency as well as the elimination of the loading problem on the output.  The transistor used in the old circuit would cause the tone frequency to change at high levels.  This month's circuit eliminates all those problems __ Designed by Radio Amateur Society of Norwich

Infinite melody for music synthesizers -  The name of this module is a play on its function.  Put simply, it generates a series of semi-random or themed stepped control voltages, or if you prefer, white and pink control voltages.  The pink function is probably better known as 1/f, and thus the name of "1l/lfinite melody". __ Designed by Ken Stone

Infrared cordless Headphone Amplifier -  Using this low cost Project one can reproduce AUDIO from TV without disturbing anyone.  It does not use any wire between TV and HEADPHONE.  In place of pair of wires it uses invisible Infrared light to transmit audio signals from TV to Headphone.  Without using any lens a range of up to 6 meters is possible.  Range can be extended by using Lenses and Reflectors with IR sensors comprising transmitters and receivers.  IR transmitter uses two-stage transistor amplifier to drive two IR LEDs connected in series. __ Designed by YMYA electronics-IZHAR FAREED

Infrared Theremin Musical Instrument -  The constituents of the electronic circuitry in the invention are represented in the following figure, "Block Diagram of the Optical Theremin.  " Note that the interconnecting lines and arrows in the figure are representative of the signal process sequence, and not representative of specific electrical connections __ Designed by Arthur Harrison

Infrared TV/VCR Remote Booster -  This circuit will boost the signal from any infrared TV or VCR remote, extending the range by a factor of 3X.. . . Circuit by Dave Johnson P.E.-October, 2005

Inside Story: Audison LR604XR Amplifier (Car Audio) -  Of the few car amplifiers I tested, gutted, decyphered and fixed, this one seems to be the best in design quality.  Too many car amps (although solidly built) are apparently designed by computer class students, too many traces, too many vias, absolutely wrong component placement etc.  And on schematic level, their different functional parts look like a newspaper clip collection.  If the amp __ Contact: klausmobile @ yahoo.Com

Integrated Audio Amplifiers -  In a previous article I discussed building audio amplifiers using discrete transistors.  While it is possible to build good audio amplifiers from discrete transistors, they are no match for the many audio amp IC's available to us.  IC's offer many advantages including high efficiency, high gain, low standby current, low component count, small size and , of course, low cost.  It is little wonder that audio amp IC's have replaced discrete transistors in most consumer electronic devices.  While __ Designed by Mike Martell N1HFX

Intercom with Musical Ringtone -  Here’s a low-cost two-way intercom circuit with musical ringtone that can be made using readily available components (see Fig.1).Melody generator IC UM66 (IC1) generates ringtone for the intercom circuit.  The __ Electronics Projects for You

Interface MIDI Instruments to a PC through a USB Port -  04/17/08  EDN-Design Ideas You can interface MIDI-equipped musical instruments to a PC via a USB port __ Circuit Design by Stefano Palazzolo, Senago, Milan, Italy

Interfacing Microphones to Computer Sound Cards -  AN047-P:  InterfaceLVDS: Interfacing LVDS to PECL; LVPECL; CML; RS-4422 ans Signal-ended Devices

iPod Super Dock Project (Part 1) -  This one goes out to everyone that has an iPod or two laying about and an itchy soldering iron and thinks that the standard USB or Firewire dock just isn't quite good enough.  The tiny thirty pin dock connector on the bottom of later model iPods contains quite a

iPod Super Dock Project (Part 3) -  This one goes out to everyone that has an iPod or two laying about and an itchy soldering iron and thinks that the standard USB or Firewire dock just isn't quite good enough.  The tiny thirty pin dock connector on the bottom of later model iPods contains quite a

iPod Super Dock Project (Part 4) -  This one goes out to everyone that has an iPod or two laying about and an itchy soldering iron and thinks that the standard USB or Firewire dock just isn't quite good enough.  The tiny thirty pin dock connector on the bottom of later model iPods contains quite a

iPod Super Dock Project (Part2) -  This one goes out to everyone that has an iPod or two laying about and an itchy soldering iron and thinks that the standard USB or Firewire dock just isn't quite good enough.  The tiny thirty pin dock connector on the bottom of later model iPods contains quite a

IR Detector for Robot -  How to build a simple IR detector, schematics and alternate links __ Designed by DC Reagan

IR Music Transmitter & Receiver -  Using this circuit, audio musical notes can be generated and heard up to a distance of 10 metres.  The circuit can be divided into two parts: IR music transmitter and receiver.  The __ Electronics Projects for You

IR TV/VCR Remote Booster -  This circuit will boost the signal from any infrared TV or VCR remote, extending the range by a factor of 3X. . . . Hobby Circuit designed by David Johnson P.E.-October, 2005

Isolated Telephone Interface -  This circuit allows you to record audio from a telephone line into a tape recorder or computer soundcard.  Most of the parts for this circuit can be scrounged from an old modem, with some work, it is possible to rewire the modem circuitry and use the old modem case __ Designed by G. Forrest Cook


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Audio Amplifiers:   #'s       A - D        E - M        N - R      S - U        V _ Z


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