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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     
   V - Z

Last Updated: October 24, 2017 02:54 PM

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:

Micro Spy with FETs -  Circuit and notes only, no circuit description given. __ Designed by Tony van Roon  VA3AVR

Micro Spy with TTL -  This circuit is old (70's) but since the 74LS13 is from the regular 74xx series and easy to obtain, I decided to keep the circuit in place until components are no longer available. __ Designed by Tony van Roon  VA3AVR

Micro Spy with USW -  Circuit and notes only, no circuit description given. __ Designed by Tony van Roon  VA3AVR

Micro-Amp -  A miniature amplifier with an outboard power supply which was built to compliment the Audax mini-monitors.  The amplifier uses an LM4780 and incorporates an over-temperature trip.  Output power is around 25 watts per channel. __ Designed by Mark Hennessy

Microcontroller (AT89C2051) based tachometer -  Just point the light-sensitive probe tip atop the spinning shaft towards the spinning blade, disk or chuck and read the rpm.  The only requirement is that __ Designed by PrOF. K. PADMANABHAN

Microcontroller converts digital-temperature-sensor readings without floating-point arithmetic -  03/05/09  EDN-Design Ideas Convert digital-temperature-sensor readings without floating-point arithmetic __ Circuit Design by Jordan Dimitrov, Toronto, ON, Canada

Microphone & Guitar Amplifier using TDA2005M -  10W Old-Style ultra-compact Combo; Two inputsOverdrive Treble-enhancement __ Contact: Flavio Dellepiane, fladello @ tin.it

Microphone from a Speaker -  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

Microphone Mixer -  Designed for 3-dynamic microphonesThis relatively simple mixer was designed for three dynamic microphones, but can be re-designed for more or less.  Level and tone controls are available to tailor the sound to your needs. __ Designed by Aaron Cake

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, 2002

Microphone phantom power supply -  This is a very simple design for a phantom supply.  This design will work with microphones that have no problem with the phantom supply being only 15V.  It also has to be noted that, at high SPL, distortion can become intolerable (totally depending on microphone design).  In that case, the phantom supply voltage has to be increased. __ NewLine

Microphone Polarity Tester -  Many things can go wrong in a modern recording studio, but few are as difficult to track down as reversed microphone polarity.  When a microphone is placed in front of a sound source, a positive pressure on its diaphragm caused by forward-moving air results in a positive voltage on one of its output pins and a negative voltage on the other.  But which pin is positive? These days most microphones have XLR output connectors, with Pin 2 used for the positive voltage output and Pin 3 for the negative.  But you can't always count on this, especially if the microphone is an older model, or was ever repaired or otherwise rewired. __ Designed by Ethan Winer

Microphone preamp for portable transceivers -  Schematic only, no circuit description __ Designed by Guy Roels ON6MU

Microphone pre-amp with high emphasis -  Ham RadioSchematic __ Designed by Guy Roels ON6MU

Microphone PreAmplifier -  This is a simple microphone preamplifier circuit which you can use between your microphone and stereo amplifier.  This circuit amplifier microphone suitable for use with normal home stereo amplifier line/CD/aux/tape inputs.  This microphone preamplifier can take both dynamic and electret microphone inputs (preamplifier provides power foe electret microphone elements).  The idea of this circuit is to keep the design as simple as possible __ Designed by Tomi Engdahl

Microphone Preamplifier -  A low noise pre-amplifier suitable for amplifying dynamic microphones with 200 to 600 ohm output impedance. __ Designed by Andy Collison

Microphone Test Oscillator -  This unit would be mounted in a small plastic or preferably metal box, with a 9V battery, level control, a male XLR connector (same as on a mic) and a switch.  Current drain is low, since the circuit only uses one dual opamp.  There is no need for a high quality device, and a 1458 (or 4558 which is somewhat better but still cheap) is all that is needed __ Designed by Rod Elliott  ESP

Microphone Tester -  This circuits is handy for finding an intermittent short or open in a microphone cord or switch.  It produces a week tone in the microphone so that you can flex the cord and operate the switch to find faults.  It won't find an open shield or a short from __ Designed by Andrew R. Morris

Microphone to Neck Loop Coupler for Hearing Aids -  Hearing-aid wearers often have difficulty understanding conversations in noisy environments, especially if they have switched their personal hearing aid from microphone mode to T-coil mode.  This projects solves that problem. __ SiliconChip

Microphone uses "phantom power" -  08/30/01 EDN-Design Ideas The electret microphone capsule is similar to those commonly used in telephones, cassette recorders, and computers.  The element functions as a capacitor with a fixed trapped charge.  Sound pressure moves a diaphragm, producing variations in the capacitance.  This action produces an ac-output voltage with an extremely high source impedance __ Circuit Design by Bruce Trump, Texas Instruments, Tucson, AZ

MIDI Controlled Switches -  Drives up to128 individual relays, solenoids, motors, etc.  with a MIDI note-on and note-off messages  

MIDI Controller Foot Pedal -  Here's a simple project that sends continuous or switch controller MIDI messages that correspond to the position of a potentiometer.  Given a few parts and a cannibalized volume or wah-wah pedal, you can build this MIDI controller pedal and have the ultimate source of controller data in the Universe.  This pedal is especially useful in live performance, but it's also great to have around when sequencing.  An added bonus: the MIDI Footpedal sports a panic button that will silence any stuck notes that come your way. __ Designed by Paul Messick

MIDI Drum Machine Analog Input Schematic -  Schematic only __ Designed by Paul Stoffregen

MIDI Drum machine project -  The MIDI Drum Machine began in the Fall of 1991 as a project for a microprocessor system design course, shortly after I wrote PAULMON1, the 8051 monitor/debugger. __ Designed by Paul Stoffregen

MIDI Generator -  Control some MIDI device with ATtiny26.  The code can be convert it for any AVR family microcontroller __ Designed by Vassilis Stergiopoulos

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

MIDI Pedalboard encoder & background information -  Almost any commercial electronic keyboard today will provide a MIDI output, which is useful for connecting it to other instruments including some pipe organs.  However MIDI pedalboards are much rarer, which among other things makes it difficult to put together a simple home practice facility.  Therefore this article  shows how the appropriate MIDI signals can be generated from the closure or opening of a simple key contact.  Full details are included for a MIDI encoder suitable for a standard 30 or 32 note pedalboard; the encoder uses only a handful of standard integrated circuits, thus removing the need to program microprocessors or read-only memories for which few have the knowledge or facilities. __ Designed by Colin Pykett

MIDI Tester -  Sometimes when experimenting with different soundcards and MIDI interfaces it is useful to see if there is some data going in MIDI interface.  This can be easily tested with this adapter, which converts the midi signals to visible light pulses.  Just the circuit and plug it to the MIDI output of your computer.  When computer sends any midi data out, you see the LED flashing.  I found this tester very useful in testing homebuilt soundcard MIDI interface. __ Designed by Tomi Engdahl

MIDI2cv8 to Drum Tone Board Connections -  Power for the Drum Tone Board can be tapped from the midi2cv8 aux.  power connections using the parts shown to the left.  The nominal "+5" bias line of the Tone Board will be more like 7 or 8 Volts using the values shown and the Tone Board will like this fine (better than 5V, actually). __ Designed by John Simonton

Midibox 64 -  Schematic Only

Mike Muter for Singing Guitarists -  The average musical Do-It-Yourselfer starts building guitar effects by making a distortion pedal of some sort.  It's a good introduction to musical electronics, and pretty simple as well, since getting a circuit NOT to be linear has never been hard.  But there comes a time when you have to stop thrashing the strings in your bedroom, get up on stage and *play*.  When you get to there, you run into all kinds of little problems that you never encountered back in your room. __ Designed by R.G. Keen

Mike Pads & Other Small Gadgets -  Includes Active Direct Box circuit

Mike Preamp Power Supply with Phantom Power -  Uses a single 48 VAC center-tapped transformer __ Contact: info @ forsselltech . com

Minature FM Transmitter #7 -  There is no thrill like the thrill you get from operating equipment you have built yourself.  If you have never built a project from a magazine before, let this be your first--you'll see how much satisfaction and fun you can have! __ Designed by Tony van Roon  VA3AVR

Mini 2W Amplifier by TDA7052 -  Here is a simple and humble mini 2W amplifier suitable for small pocket radios and other portable audio gadgets.  The circuit is based on Phillips Semiconductors IC TDA 7052.  The amplifier can be run even from a 3V Mercury button cell.  This makes it ideal for battery operated gadgets

Mini Audio Mixer -  This is simple mini audio mixer.  This circuit consume low current due to the simple design.  Also featuring three inputs with switchable high/low sensitivity and unusual level-control circuits, providing high overload margins and low-noise figures, proportional to gain-level settings.

Mini Bench Amplifier -  This mini audio amplifier will test the audio stages in amplifiers such as the front end of FM bugs.  You can also use it on lots of our other projects as well as the output stages of radios.  It is a very handy piece of test equipment and will make a perfect addition to your collection __ Contact: Collin Mitchell

Mini Guitar/Bass Amplifier -  Output power: 6W into 4 Ohm load; FET input stagePassive Tone Control __ Contact: Flavio Dellepiane, fladello @ tin.it

Mini Metronome -  Linear scale Small size.40 to 208 beats per minute __ Contact: Flavio Dellepiane, fladello @ tin.it

Mini Portable Guitar Amplifier -  Can be fitted into a packet of cigarettes.    Also suitable as Fuzz-box __ Contact: Flavio Dellepiane, fladello @ tin.it

Mini Sixties Plus -  This circuit is inspired by an amplifier published in the ’60s that produced 8 watts a channel into 8 Ohm and was based on AD161 and AD162 germanium (not ‘geranium’) power transistors.  These at last made it possible to build complementary-symmetry power stages with performance similar to that obtained with the standard at the time: a class AB ‘push-pull’ using with two EL84 pentodesmust register on this site __ Designed by Published in Elecktor July/Aug, 2010

mini Theremin Mk.2; Pt 2 -  Last month, we described the features of our new Theremin and gave the full circuit details.  This month, we show you how to build it and describe the adjustment procedures. __ SiliconChip

Mini Theremin Mk.2; Pt.1 Just move your fingers near the antennas of this theremin to create your own electronic music or eerie science fiction sounds.  It's easy to build, easy to set up and easy to play. __ SiliconChip

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


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