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Amplifiers: Audio Circuits
Amplifier -- Main Page          Audio Amplifiers Circuits -- Main Page

Audio Amplifiers:   #'s       A - D        E - M        N - R      S - U     
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Last Updated: December 30, 2017 02:09 PM

Circuits Designed by Dave Johnson, P.E. :
Audio Amp + 3Khz Filter  -  This circuit is the audio amp section for a complete optical transmitter.  The circuit amplifies and filters the voice audio signals from an electret microphone.  The circuit is described in more detail in . . . Circuit by David Johnson P.E.-June 04, 2000

Band Drummer’s Microphone Switch  -  I received an email from guy who plays drums for a small band.  He wanted a simple way to turn on and off his microphone with just a tap of his drum stick onto a small box.  The circuit below performs this task with the aid of a piezo device as a shock sensor and a small dual coil latching relay with two sets of contacts.  The contacts can be wired any number of ways to a microphone circuit . . . Hobby Circuit designed by David A. Johnson P.E.-October 16, 2011

Boost Infrared TV/VCR Remote Signal  -  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 Dave Johnson P.E.-October 05, 2005

DVD Recorder + TV Camera Make Cheap Data Logger  -  Sometimes recording the results of a test requires as much ingenuity as designing the product.  Consider a situation which requires the collection of many different variables over a long period of time . . . Hobby Circuit designed by David A. Johnson P.E.-April 01, 2005

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

A 2-channel guitar preamplifier -  Each channel has bass, mid and treble controls and there's an optional digital reverberation unit as well. __ SiliconChip

A 2SK1058 MoS-FET Amplifier -  Want to construct an amp that had zero negative feed back   (0NFB) , was pure Class A and definitely single ended __ Designed by Michael LaLena

A Better Volume Control -  A volume control using a linear pot that is much better than most log pots __ Designed by Rod Elliott  ESP

A Dead-Simple Circuit Masthead Amplifier -  Decided to take the plunge and get into digital TV? For most people, it's simplejust plug the new TV or set-top-box into your existing antenna.  But for many, the old TV antenna and cable just won't be up to it.  Here?s a new kit from Oatley Electronics which could solve your digital woes__ SiliconChip

A Direct Injection Box for Musicians -  Don't put up with hum.  This versatile DI box converts an unbalanced input to a balanced output signal and includes a 3-band equaliser. __ SiliconChip

A Discrete FET Guitar Preamp -  I've been performing experiments with guitar preamps and on-board electronics since, oh, the Nixon adminstration or thereabouts.   Sometime around 1990 I designed this preamp circuit, and have been using it mostly unchanged ever since.   In 1992 I posted a schematic of the preamp to one of the Usenet groups and the circuit became somewhat popular. __ Designed by J. Donald Tillman

A Gainclone for the PC Age -  Audio input comes from either the Line-Out of the PC or an external sound card   (described later).  A small filter consisting of 680Ω/47pF excludes any RF signals from entering the case.470nF input capacitor should have a high voltage rating since it protects against line voltages being connected to the amplifier, since it is in the signal path it should be a high quality type __ Designed by Malcolm Rix

A Musical Distortion Primer -  This is an introduction to the basic means of distorting a signal in a musically useful way.  The approach is as non-technical as possible.    I use the simplest signal waveform, a sine wave, to illustrate all these, although a guitar is much more like a sawtooth than a sine wave.  The clipped waveforms will be shown in their raw state __ Designed by R.G. Keen

A PIC-Based Musical Tuning Aid -  This compact device will help you tune almost any musical instrumentacoustic or electronic.  It can produce any note on the tempered musical scale   (standard pitch) in any of the eight most commonly used octaves, with an accuracy of better than ?0.08% or 1.3 musical cents.  The selected note is compared with that from the instrument either by ear or visually by using an eight-LED stroboscopic beat indicator. __ SiliconChip

A Simple Circuit & Small Audio Amplifier -  Extremely Simple and useful for many applications. __ Designed by G.L. Chemelec

A Simple Circuit audio mute -  20 kB PDF file.  If you're using discriminator audio and need to mute it, this circuit will do the job.  Sent anonymously to repeater-builder.  

A Simple Circuit Capacitance Multiplier Power Supply for Class-A Amplifiers -  A basic circuit is provided in the article, but it is assumed that the builder knows all the pitfalls.  The supplied schematic is in fact for a capacitance multiplier filter   (not a regulator) , but is somewhat lacking   (I feel) and can be improved dramatically __ Designed by Rod Elliott  ESP

A Simple Circuit Musical Light -  The circuits for musical lights available in the market are highly expensive and based on microcontrollers.  Also, their programming is very difficult.  Here is a simple and cheap circuit for a __ Electronics Projects for You

A Tremolo Unit for Musicians -  Jazz up your music with this easy to build unit. __ SiliconChip

A Vacuum Tube Microphone Preamp/ Direct Box Project -  From January 1997 EQ Column, includes phantom power supply

A Weighting Filter for Audio Measurements -  For noise measurements.  Ideal for use with the AC Millivoltmeter above __ Designed by Rod Elliott  ESP

A/V Sender -  This small circuit transmitter processes the signs of audio of a sound table or microphone, and the signs of video of a camera, or still the audio signs and video of a DVD, Video-cassette or even it sweats her video plate has an exit of composed video, you can transmit direct of your computer.  Playing them in a channel free from the strip of VHF __ Designed by Toni on Aug 19, 2009

A4 Power Amplifier -  This is a 4 channel amplifier that uses LM4780s working in parallel mode.  There are options for bi-amping or bridging.  Each channel is rated at around 50 watts per channel, but bridged, it produces over 150 watts per channel. __ Designed by {Mark Hennessy

A440 Synth Tuning Crystal Controlled Oscillator -  A cheap little crystal controlled sine wave reference oscillator unit, for tuning your analogue synth to. __ Designed by Henry 

AC Power Line Power Load Sensing Automatic Switch -  WARNING:  This circuit requires experience with mains wiring.  Do not attempt construction unless experienced and capable.  Death or serious injury may result from incorrect wiring. __ Designed by Rod Elliott  ESP

Active 3-Way Crossover for Loud Speaker Systems -  Get the very best from your 3-way loudspeaker system with this easy-to-build high-performance design. __ SiliconChip

Active Bass & Tremble Controller -  It is very useful   (and has Best Quality) for 1 -100watt AUDIO AMPLIFIERS __ Designed by har Fareedizhargmx.us

Active HiFi speakers -  A pair of large three-way speakers with built-in active cross-over and expanded class-A amplifiers, exhibiting very high sound quality, while being neither hard to build, nor expensive.  Schematic diagram, printed circuit board layout, and several photos are included. __ Designed by Manfred Mornhinweg

Active Load in Gain Stage -  Instead of a resistor at the transistor's collector, you might have seen a current source   (active component) substituted in an audio amp's gain stage.  Why go through the trouble of the added components? You'll find the active loading of a current source packs   (spice design) 

Active Subwoofer & Controller -  Designed to operate a sub-woofer driver below its resonant frequency __ Designed by Rod Elliott  ESP

Active-filter & oscilloscope inspect a Class D Amplifiers output -  12/01/06  EDN-Design Ideas Ease debugging of bridge-output pulse-width-modulated audio amplifiers with this circuit __ Circuit Design by John Guy, Maxim Integrated Products Inc, Sunnyvale, CA

AcTVie speaker based on a dual op-amp (LM833) & TDA2030 power Amp -  This is a simple powered loudspeaker that was originally intended to be used as a simple piece of test equipment.  It is based around a small full-range loudspeaker that I'd inherited, which originally came from Radio Spares __ Designed by Mark Hennessy

Add harmony to your systE - M -  07/20/00 EDN-Design Ideas Have you ever wished you could distinguish one device's operating state from anor's by sounds y make or that error states would sound harsh while normal operations would sound harmonious? By combining  NCO technique from a previous Design Idea  (Reference 1] __ Circuit Design by Eugene O -- EDN

Add music to your next project -  12/23/99 EDN-Design Ideas Adding music to your next design is as simple as using one I/O pin to drive the speaker and approximately 150 words of program memory to play the music.  You can store the musical notes and durations internally in program memory or externally in a serial EEPROM.  Frequently, implementing musical playback requires an external processor with memory or a specialized __ Circuit Design by Rodger Richey, Microchip Technology Inc, Chandler, AZ

Adjustable Audio Notch Filter -  A variable notch filter with both high and low pass filters. __ Designed by Andy Collison

Adjustable bass filter from 50 Hz to 150 Hz-Ne5532 Bass Filter with volume control -  This is a bass filter, using the OpAmp Ne5532 or another of your choice.  The circuit is simple to set up and already has symmetrical power supply, the transformer must use 9-12 volts / 500ma with center tap … In many cases the power source can be made by the power amplifier … Just watch […] __ Designed by Antonio Rodrigues

Advanced Audio Amplifier -  This is roughly the minimum number of components that represents the classic audio amplifier topology.  You can clearly see the three stages found in many audio amps   (and op amps today).  However, looking at actual audio designs, you'll find the basic topology has been tweaked and enhanced in a few key locations   (spice design) 

AF Pre-amp for Kenwood Mc-50 microphone to improve high frequency responce (high emphasis) -  Ham RadioSchematic __ Designed by Guy Roels ON6MU

AGC Dynamic Microphone -  Dynamic microphones have a fantastic dynamic range, easily handling whispers to rock concerts.  The signal level range coming out of a dynamic microphone can be huge and an AGC amplifier can prove quite handy.  This project employs an old hobby dynamic microphone mounted in a film canister with the AGC amplifier tucked inside.  The LED/photocell is an ordinary LED glued to the top of a small CdS cell from a night light, covered with black 'liquid tape'.  The top of the LED was sanded flat to make it easier to glue to the flat cell face.  The pair is visible to the left of the output level potentiometer, above the op-amp __ Contact: Charles Wenzel of Wenzel Associates, Inc.

All About Audio Amplifiers -  Amplifiers would be nothing without tone controls.  They allow us to boost or cut the low and high ends of the audio spectrum.  Nobody would buy an amplifier or preamp that did not have them.  Because these controls are so important designers spend a lot of time and effort on these circuits __ Designed by Max Robinson

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