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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 07, 2017 02:03 PM

Circuits Designed by Dave Johnson, P.E. :
TV /VCR Remote Range Extender Circuit  -  I often get frustrated by how poor some infrared remotes in many new electronic devices operate.  I used to be able to turn on the TV from 30 feet away.  Now, it seems that I have to get within 15 feet.  To address this issue, I designed the circuit shown below.  The circuit taps into the TV remoteís existing infrared LED and drives 8 more efficient devices.  The result is a communications range some 4 to 5 times longer.   . . . Circuit by Dave Johnson P.E.-October 05, 2005

Video Signal Edge Enhancements  -  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 . . . Circuit by David A. Johnson P.E.-July 08, 2000

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

Tube active crossover -  Let me start by saying that I'm not a filter expert.  I've certainly designed many active filters in my career, but I don't have an understanding of the complex mathematics involved, so I'm basically a cookbook filter designer.  I took standard filter design and put in tubes as the active elements.   For a very good text about designing active filters, look at this from Texas Instruments"Active Filter Design Techniques", excerpted from "OpAmps For Everyone", also an excellent book.  Although this describes filter design using opamps, the principles all apply to tube circuits as well.  Another good reference is App Note OA-26 from National Semiconductor. __ Designed by Pete Millett

Tube Amplifier Kit -  The amplifier kit uses two 11MS8 tubes per channel.  The two DC blocking capacitors and the four coupling capacitors are metallized polyester, while Samsung aluminum electrolytic capacitors are used to filter the solid-state power supply.  

Tube Car Stereo Amp -  YES, a tube amp in a CAR!!! __ Designed by Bob Danielak

Tube Line Driver/Preamp -  Published in Glass Audio #2/1993 __ Contact: info @ forsselltech . com

Tube Microphone Preamp -  This preamp design started out as a conventional three stage cascade with feedback RIAA equalization.  I decided on 6SL7's running into 6SN7's.  I figured it would be a good match (electrically and asthetically) for my 2A3 Amp.  After thinking it through I thought I might just try passive RIAA.  (Even a better matchno feedback!!!) I noticed a neat RIAA preamp circuit in the back of the RCA Tube Manual RC-19 that used a single 7025 per channel __ Designed by Bob Danielak

Tube Screamer-based overdrive -  Tube Screamer-based overdrive. __ Contact: holler @ runoffgroove.Com

Tube Sound Fuzz Adaptation -  Mark Hammer's Tube Sound Fuzz Adaptation __ Designed by Guitar Effect RC Keen

TV /VCR Remote Range Extender Circuit -  I often get frustrated by how poor some infrared remotes in many new electronic devices operate.  I used to be able to turn on the TV from 30 feet away.  Now, it seems that I have to get within 15 feet.  To address this issue, I designed the circuit shown below.  The circuit taps into the TV remoteís existing infrared LED and drives 8 more efficient devices.  The result is a communications range some 4 to 5 times longer.. . . Circuit by Dave Johnson P.E.-October, 2005

Twin Line Telebalance Unit -  Again, made for Radio Glen.  Quote from then station manager Lex, "Beats the living fish out of those analogue Sonifex units.  " __ Designed by Henry 

TwinTen Stereo Amplifier -  Build this gutsy little amplifier for your Discman, MP3 player or games machine __ SiliconChip

Two 9v battery-powered Amps based on the LM386. Schematic & PCB/perfboard layouts. -  For better compatibility with effects driving the Little Gem, a FET buffer can be added.  Both the Little Gem Mk II   (seen below) and Ruby schematics include a simple buffer design.  No further circuit modifications are necessary, however the input capacitor value of the amp may need to be adjusted to taste. __ Contact: holler @ runoffgroove.Com

Two channel distortion -  Two channels of buxom distortion. __ Contact: holler @ runoffgroove.Com

Two Line Mixer -  Sometimes there is need to combine the output of two line level audio sources to be fed to one input.  A standard way in professional audio is to use a mixing desk, but on home audio system you might want to look for a simpler and less expensive alternative.  Some people have suggested of combining two audio outputs with an "Y-adapter" which is ment to split one output.  Those adapters are just one male connector and two feamle connector directly wired to each other in the followin way: __ Designed by Tomi Engdahl

Two Tone Audio Oscillator -  Circuit Only __ Contact: Peter Parker VK3YE

Two Transistor Wein Bridge Oscillator -  Scroll Down to find this circuit.  Here is a two-transistor Wien bridge oscillator using an ordinary night-light bulb for stabilization.  The output is about 6 volts p-p and can drive fixed loads as low as 2 or 3 thousand ohms without additional buffering.  A 10 k amplitude potentiometer. __ Contact: Charles Wenzel of Wenzel Associates, Inc.

Two Watt Amplifier -  An audio amplifier made from discrete components with 2 Watts audio power into an 8 ohm load.  Carlos has used this amplifier on his AM radio for many years. __ Designed by Carlos Feldman

Two way cross-over 3500 Hz  -  High Quality simple unit ;No need for a preamplifier. __ Contact: IQ Technologies

Two-channel audio Amplifier drives stepper Motor -  12/01/06  EDN-Design Ideas Pulse-width-modulated stereo power amplifier saves components __ Circuit Design by Phill Leyva and Bill Quach, Maxim Integrated Products, Sunnyvale, CA

Two-Input Mixer -  As simple as it gets.    mixer consists of two transistor-based preAmplifiers.    first one (designated "Mike in") offers higher gain.  it works well with a regular dynamic microphone.    second one can be used to control audio input from a tape recorder/CD player.  

Two-Tone Siren using One 4093 IC -  This circuit is intended for children fun, and can be installed on bicycles, battery powered cars and motorcycles, but also on models and various games and toys.  With SW1 positioned as shown in the circuit diagram, the typical dual-tone sound of Police or Fire-brigade cars is generated, by the oscillation of IC1A and IC1B gates. __ Red Free Circuits

Two-Tone Train Horn -  With this circuit you can electronically simulate the noise of a diesel-train horn.  The sound is triggered automatically as the train reaches a desired place on the track so you can produce the sound as the train approaches stations, level crossings, etc.  The circuit can be built simply by using one 556 or two 555 timers __ Designed by Tony van Roon  VA3AVR

Two-Transistor Audio Amplifier -  It has been interesting analyzing these radios.  You have to give the Japanese credit for even making a radio that can drive a speaker with only 2 transistors!Basically, the first transistor   (Q1) performs double-duty.  It first acts as an RF amplifier, with some of the signal being fed back to the antenna coil to provide some regeneration for better selectivity and sensitivity __ Designed by schematic and circuit description were provided Ronald Rissel

UBE Screamer -  A CMOS implementation of the Tube Screamer. __ Contact: holler @ runoffgroove.Com

Ultra Simple Circuit Bass Guitar Compressor -  An ultra simple compressor, ideally suited for bass guitar. __ Designed by Rod Elliott  ESP

Ultra Simple Circuit Line Mixer for the Studio  -  Because we needed a mixer for some shows that our band is doing, I felt the need to make a simple line mixer to run the sound modules through in the studio to free the Mackie mixer for our shows.  Up until now it has been a real hassle to yank out the Mackie from the studio everytime we had to do a show. __ Designed by Jon Tirone, AKA John Fisher

Ultra-LD 2x100W Stereo Amplifier Pt.1 -  This no-holds-barred audio amplifier is rated at 100W RMS per channel and has very low distortion. __ SiliconChip

Ultra-Low Noise Low Distortion Audio Op Amp -  LT1115 __ Linear Technology/Analog Devices

Ultra-Low Quiescent Current AF Power Amplifier -  This is an audio power amplifier, similar to what is common in transistor radios and other portable audio equipment.    This circuit however, has an ultra-low quiescent current of about 250uA, due to a unique bias circuit.  I donít even know of a chip that d __ Designed by Andrew R. Morris

Ultra-low-noise low-dropout regulator achieves 6-nV/√Hz noise floor -  06/23/05  EDN-Design Ideas LDO has ultralow-noise output __ Circuit Design by Ken Yang, Maxim Integrated Products Inc, Sunnyvale, CA

Umble-A distortion stompbox, inspired by Dumble Amplifiers. Schematic & PCB/perfboard layouts. -  A distortion stompbox, inspired by Dumble amplifiers. __ Contact: holler @ runoffgroove.Com

Universal Buffer -  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

Universal Musical Interface -  Just a picture for now __ Designed by G. Forrest Cook

Universal Preamplifier -  Most audio amplifier systems must have preamplifiers with many different characteristics.  These include high-gain linear response for magnetic microphones, low-gain linear response for tuners, and high-gain RIAA equalization for magnetic phone cartridges. __ Designed by YMYA electronics-IZHAR FAREED

Uno-The Boogie MkI -  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

Urei 527 Equalizer Schematic -  Schematic only __ Contact: Waltzing Bear Audio

Urei 545 Parametric Equalizer Schematic -  Schematic only __ Contact: Waltzing Bear Audio

Urei LA 2A Schematic -  Schematic only __ Contact: Waltzing Bear Audio

Urei LA 4, this is the black faced LA4, uses 846 op Amps Schematic -  Schematic only __ Contact: Waltzing Bear Audio

Urei LA 4A, silver LA-4, uses all 4136 op Amps Schematic -  Schematic only __ Contact: Waltzing Bear Audio

USB Sound Card with PCM2702 -  Make a sound card is no more a complex issue.  If you use great IC PCM2702 from BURR BROWN / Texas Instruments you can create a fully functional USB sound card.  This sound card can be __ Designed by Miroslav Batěk  Prague, Czechia

Use Amplifier Phono Input as Line Level Input: Inverse RIAA Filter -  The circuit does two functions: signal level attenuation and inverse RIAA filtering.  The signal attenuation is needed to convert the 500 mV signal to 2.5 mV signal.  The inverse-RIAA filtering is needed to make the frequency response of the system flat (same equalization that is used when music is transferred to vinyl in the studio).  The picture __ Designed by Tomi Engdahl

Using a Speaker as a Microphone -  A circuit to Impedance Match a Speaker as a Mike.    Speakers can make a Good Microphone for some applications.    Bigger Speakers may also have a Good Low Frequency Response.     Ever seen a 15 Inch Microphonethis Circuit will do it __ Designed by G.L. Chemelec

Using an AVR -  Tiny13V microcontroller as step up (boost) or step down (buck) voltage converter for driving a white or high power LED.  (pdf file) LED headlamp projects. __ Designed by Steven "Melt Solder" Weber  KD1JV

Using an old Computer Box to build a guitar Amplifier -  In the event of the new ATX computer boxes, the former boxes for PC will become and are becoming obsolete.  It is almost unimaginable how many unused computer boxes will be unused or trashed very shortly in history.  That's a lot of metal.  They will be and are already common articles in junk shops, flee markets and garage sales. __ Designed by Jon Tirone, AKA John Fisher

Using ECM Mic Inserts -  This page describes how to use or connect and use 2 and 3 terminal electret condenser microphones (ECM's).  The bottom section shows the connections and how to substitute from one type to another. __ Designed by Andy Collison

Using the Hot Springs Reverb reverberation unit -  The Hot Springs tanks and circuit board should be mounted in a location that is free of ambient electro-magnetic fields.  The input and output jacks are typically placed on a patch panel with other effect's inputs and outputs.  In use, the effects or aux send buss of the console patches to the Hot Springs input and the output of the Hot Springs returns to one of the mixer inputs for control of reverb level in the total mix.h __ Designed by John Simonton

Using your Op-Amp in the real world -  Almost all active (semi-conductor or tube based) audio units add some degree of DC voltage bias.  What this means is that the audio signal can have positive or negative voltage bias, this is something that can cause large distortion errors, __ Designed by Jens Moller

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

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