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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: June 02, 2021 01:44 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 and designs for engineers, hobbyists, students & inventors:


Balanced Floating Output Stage Circuit -  A great output topology based on a Design by George D Pontis __ Contact: info @ forsselltech . com

Balanced Input Amplifier Module -  Variable-gain additional unit for the Portable Mixer;  Suitable for low impedance microphones __ Contact: Flavio Dellepiane, fladello @ tin.it

Balanced Line Driver & Receiver -  Use these to eliminate hum for long signal leads __ Designed by Rod Elliott  ESP

Balanced Low Noise Microphone Preamp -  A discrete front end makes this balanced microphone preamp very quiet __ Designed by Rod Elliott  ESP

Balanced/unbalanced converter for audio work -  If you work in the professional audio field, you need to use balanced lines for long signal runs to prevent hum and noise pick-up.  This Balanced/Unbalanced Converter is really two projects in one.  It can convert an unbalanced input to balanced outputs and vice versa. __ SiliconChip

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, 2011

Basic Audio Amplifier -    (spice design) __ Designed by Rick 

Bass Booster -  a simple active op-amp filter that will boost and cut bass signalspossibly as part of a sub-woofer __ Contact: P. Townshend EduTek Ltd

Bass EQ pre-amp correction for high impedance ceramic crystal PU -  Ham Radioschematic __ Designed by Guy Roels ON6MU

Bass Guitar Amp -  I've been wanting to put these EL509's to use!!! Figured a nice high-power bass guitar amp would be a perfect application.  I have the amplifier built to the point shown in the schematic, above.  Initial testing with tone-stack replaced with a 10:1 voltage divider is very promising.  Still need to decide on the tone stack arrangement.  The unit is built as a stand-alone head, and will be used with a Peavey 15" + 2x 10" Bass cabinet __ Designed by Bob Danielak

Bass/Treble Tone Control -  a neat little circuit providing +/- 3db bass and treble boost __ Contact: P. Townshend EduTek Ltd

Bass-treble tone control -  The LM1036 is a DC controlled tone   (bass/treble), volume and balance circuit for stereo applications in car radio, TV and audio systems.  An additional control input allows loudness compensation to be simply effected.  Four control inputs provide control of the bass, treble, balance and volume functions through application of DC voltages from a remote control system or, alternatively, from four potentiometers which may be biased from a zener regulated supply provided on the circuit.  Each tone response is defined by a single capacitor chosen to give the desired characteristic. __ Designed by Tasos Anagnwstou

Bat Detector microphone pre-Amplifiers -  The microphone pre-amplifier has the job of amplifying and conditioning the signal coming from the microphone.  In case of an electret microphone, the amplifier must have a gain that increases with frequency to compensate for the low sensitivity of the microphone for high frequencies.  Also the low frequency part must be filtered out.  In case of a piezo transducer, __ Designed by Bertrik Sikken

Battery Powered Electret Microphone -  This is the basic electret microphone powering circuit which you can use as generic reference when receivign circuits which use electret microphones. The putput impedance is determined by R1 and R2. If you leave out R2 the output impedance is roughly the resistance of R2. __ Designed by Tomi Engdahl

Battery powered electret microphone -  Note: scroll down to this this circuit.  This circuit can be used with normal tape recorders and sound cards which usually are designed for dynamic microphones.  When you build this circuit insidemicrophone case   (or to small external box) you can make yourself an universal microphone out of an electret capsule. __ Contact: Charles Wenzel of Wenzel Associates, Inc.

Battery Powered Electret Microphone #2 -  This circuit can be used with normal tape recorders and sound cards which usually are designed for dynamic microphones. When you build this circuit inside the microphone case (or to small external box) you can make yourself an universal microphone out of an electret capsule. __  Designed by Tomi Engdahl

Beat Tracking Strobe -  Strobe lights have always been an integral part of dance parties, adding an additional element of excitement to the festivities on hand.  The combination of flashing lights and music-especially those with a definitive strong beat- are a natural complement to one another, where the strobing of light is an extension and links one's aural perception to his visual senses.  The applications of strobe lights are numerous.  In more involved and comprehensive applications the strobe user would like the strobe to help fuse together the music and light.  For our final project we opted to attempt to create such a strobe system appropriate for the more complex application by creating a light strobe system that flashes a light source directly in sync with the music in real time __ Designed by Chris Chan and Kenneth Liu

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

Bidirectional 2.4 GHz One Watt Amplifier This will show you how to add a bi-directional, 2.4 GHz amplifier to your Proxim Symphony for under $100.  Bi-directional means you can mount the amplifier at the antenna to help overcome any cable loss, and the amplifier will automatically switch between receive and transmit modes.  The cost is reduced by using readily available materials and components. __ Green Bay Professional Packet Radio

Bidirectional 900MHz One Watt Amplifier -  This device is a stereo amplifier for a high sensitivity stereo parabolic microphone.  It can be used for listening to distant sounds.  Typical parabolic microphones are monophonic, this unit has a stereo audio path that helps produce more realistic sounding audio.  The Big-E can be used with headphones or as an audio source for a stereo tape recorder __ Green Bay Professional Packet Radio

Big Ben Sound -  This circuit produces  famous Big Ben sound.  It produces  "ding dong" sound when switched ON.  Basically  circuit alternates between two frequencies which are adjustable.  This produces  "ding-dong" sound.  The first C   (left) oscillates at about 1Hz.  The second IC's tone is modulated by  changing voltage at  output of  first IC __ Designed by Radioland.nt.au

Big-E Stereo Parabolic Microphone -  This device is a stereo amplifier for a high sensitivity stereo parabolic microphone.  It can be used for listening to distant sounds.  Typical parabolic microphones are monophonic, this unit has a stereo audio path that helps produce more realistic sounding audio.  The Big-E can be used with headphones or as an audio source for a stereo recorder.  It can be plugged directly into a computer sound card's aux input. __ Designed by © G. Forrest Cook January 1, 2005

Binaural MICs -  I used the plans from http://www.arches.uga.edu/~tidmarsh/binmic.html.  I'm no electronics expert but can solder, and it was very easy.  If you want to build a battery box you'll probably want some fine gauge wire and a little piece of circuit board in addition to the components listed. __ Designed by Doung Brown

Bipolar Transistor Audio Preamplifiers -  Before attempting to design a transistor amplifier circuit, it is necessary to acquaint ourselves with some very important design equations.  The most commonly used design equations are listed to the right to help us with our effort. __ Designed by Mike Martell-N1HFX

Bipolar transistor mixer -  Ham RadioV-U)HF AMPLIFIERSchematic __ Designed by Guy Roels ON6MU

Birdie Doorbell Ringer -  P1 is of experimental value.  Start with 220 Ohms or so and modify to suit your needs.  The transistor is a general purpose kind and is not critical, almost any PNP type will work.  L1 is a bell-transformer which is usually already present in the house.  If you wish, you could use a battery instead of the bell transformer.  Just hookup a 9-volt battery   (or wall adapter) to points 'A' and 'B'   (A=+) the diode   (D1) is to protect the circuit from accidental polarity reversal and is optional, but required as a rectifier for use with the bell transformer __ Designed by Tony van Roon  VA3AVR

BJT Current Source -    (spice design) __ Designed by Rick 

Boogie MkI adapted for use as a distortion stompbox -  One of the first amps to offer distortion at lower volumes was the Boogie MkI amplifier.  As told by Randall Smith, the designer of the Boogie amp, these amplifiers were born of a practical joke on a guitarist friend.  Mr.  Smith modified a Fender Princeton to have considerably more gain and power, but appear stock.  As the story goes, Carlos Santana play-tested the amp and was impressed.  Carlos was quoted as saying the amp "really boogied!" Thus, the name of the amp was born. __ Contact: holler @ runoffgroove.Com

Book PC MP3 Player -  A small computer running Linux with 12 volt power supply and wired remote control makes a great sound system for a car __ Designed by Bob Blick

BookPC Car MP3 Player -  This is an earlier player using a conventional PC motherboard, so the power supply I designed is quite compatible. __ Designed by Bob Blick

Boost 3.3V to 5V with tiny audio Amplifier -  09/05/02 EDN-Design Ideas This charge-pump circuit quietly converts a 3.3V source to 5V at 500 mA  (figures 1 and 2].  National's  (www.national.com] LM4871LD power amplifier makes This design idea both possible and practical, thanks to its low output resistance, low cost, compact size, and high dissipation capability.  Its output resistance has an average value of 0 Design by Wayne Rewinkel, National Semiconductor, Santa Clara, CA

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, 2005

Bridging Adapter for Audio Power Amplifiers -  A conventional adapter for bridging power amplifiers __ Designed by Rod Elliott  ESP

Britannia -  An original overdrive inspired by the Vox AC-30 Top Boost amp. __ Contact: holler @ runoffgroove.Com

Buffer Amplifier -  A 2 stage audio pre-amplifier with very good performance.  This preamplifier has two direct-coupled common emitter stages and uses series-voltage feedback.  The circuit has high input impedance, low output impedance, voltage gain can be set independently and has low noise levels and good signal noise ratio. __ Designed by Graham Maynard

Buffer switches analog or digital signals -  30-Mar-06 EDN-Design Ideas Use an op amp and a dual SPST to switch signals under digital control __ Designed by Liviu Pascu, Kepco, Flushing, NY

Build a good Audio Buffer Amplifier -  Audio power amplifier circuit diagrams / circuit schematics __ Designed by Kevin Custer  W3KKC

Build a Loudspeaker Protector -  THE SPEAKER in the above photo is well on fire and this could be the result of a relatively minor fault in an audio amplifier.  As anyone who has been following our series on the Ultra-LD Mk.3 Amplifier would be well aware, big power amplifiers have big power supplies and so a relatively minor fault in one channel of a stereo amplifier can result in a large DC voltage being applied to one of your precious   (and expensive) loudspeakers. __ SiliconChip

Build a MIDI Drum Kit -  This do-it-yourself MIDI drum kit can produce just about any musical sound you can think of, either via a computer or a synthesiser. __ SiliconChip

Build a MIDI Drum Kit Part 2 -  Last month we introduced our latest MIDI instrument, the MIDI Drum Kit offering a staggering 546 drum sounds and not a stretched skin in sight! Here's all you need to know to put the control unit togetherand it's not that difficult __ SiliconChip

Build a MIDI Drum Kit Part 3 -  PART 3building the sensors and stand __ SiliconChip

Build a MIDI Keyboard -  Build a PIC based DIY midi keyboard for under $30 and by using free VSTs   (virtual instruments) you get a powerful music creation system

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


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