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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:

Altec 1566A:Vacuum Tube Preamp & Direct Box Project -  There are all sorts of tube circuits, some of which actually deliver The Sound people associate with Vacuum Tubes.    Did you know, for example, that asymmetrical distortion generates even-order harmonics while symmetrical distortion produces odd-order harmonics?

AM/FM Tuner/Amplifier -  First use of my 6CM5 audio output stage design along with a super regenerative detector for FM and regenerative detector for AM. __ Contact: blehack @ yahoo dot com

Amp based on a Silvertone Twin Twelve -  ampbased upon an old Silvertone Twin Twelve -- I decided to try another guitar amp   (actually, I intend to build two identical single 12" combo'sone for me and one for my TWIN brother, Rich).  Although I'm sure a Fender Deluxe knock-off would be just fine for what I needed , I wanted to do something a bit different __ Designed by Bob Danielak

Ampeg SB-12 Portaflex adapted for use as a bass overdrive stompbox -  When one thinks of classic bass amps, the brand name "Ampeg" often comes to mind.  Their SVT models were very popular and still are today.  Slightly less known Ampeg combo-type models were also made, called "Portaflex" amps.  In "travel" form, these appeared to be simple closed back speaker cabs with a pair of chrome latches on either side of the top panel.  When one released the latches, the top panel could be removed and flipped over to reveal a tube head unit.  One simply plugged in the attached speaker cable and the amp was ready to go.  The unique design led to the nickname of "Flip Tops." __ Contact: holler @ runoffgroove.Com

Amplified Ear -  This circuit, connected with 32 Ohms impedance mini-earphones, can detect very remote sounds.  Useful for theatre, cinema and lecture goers: every word will be clearly heard.  You can also listen to your television set at a very low volume, avoiding to bother relatives and neighbours. __ Contact: IQ Technologies

Amplified ear for surveillance -  To listen old vinyl LP’s in a correct sounding on a sassy with dynamic cartridge you need a circuit, named RIAA corrector.  This circuit you can find in old amps, but it isn’t embedded in home cinema equipments or amplifiers can be obtained nowadays.  Also, if you want to archive your vinyl LP’s in your computer it is necessary to use this RIAA corrector.  

Amplifier (LM3886) -  So what the heck is a Gainclone? Originally, the term Gainclone meant a clone of the 47 Laboratory Gaincard.  The 47 Laboratory Model 4706 Gaincard is understood to have the following general features __ Designed by Michael LaLena

Amplifier Bridging -  A design for a simple add-on bridging adapter for stereo power amplifiers __ Designed by Rod Elliott  ESP

Amplifier Considerations in Ceramic Speaker Applications -  App Note 4164  -- 2/05/2008 --    (add 5/08) __ Maxim Integrated

Amplifier of acoustic frequencies with preamplifier -  Minimal signal of entry: 94mVp-p with preamplifier, 0, 65Vp-p without the preamplifier. __ Contact: IQ Technologies

Amplifier removes common-mode noise on RGB differential-video-transmission line -  04/13/06  EDN-Design Ideas Use a single operational amplifier to minimize common-mode signals' effects on differential-component-video receivers __ Circuit Design by Tamara Papalias and Mike Wong, Intersil Corp

Amplifier requires no DC bias -  03/16/00 EDN-Design Ideas Intrinsically capacitive transducers and or high-impedance signal sources usually require ac coupling and a buffer amplifier to condition  signal for furr processing.  Buffers take many forms, but most of m compromise signal quality through __ Circuit Design by John Guy, Maxim Integrated Products, Sunnyvale, CA

Amplifier Thermal Protection -  The thermal protection of amplifiers is always a concern, since overheating is a sure way to reduce the life of semiconductors and other components.    Where you don't want to use a fan   (such as in Project 42Thermo-Fan for Amplifier Cooling), then a complete shutdown can be performed. __ Designed by Rod Elliott  ESP

Amplifier Timer -  This circuit turns-off an amplifier or any other device when a low level audio signal fed to its input is absent for 15 minutes at least. 
Pushing P1 the device is switched-on feeding any appliance connected to SK1.  Input audio signal is boosted and squared by IC2 A & B and monitored by LED D4. __ Contact: IQ Technologies

Amplifiers Deliver Accurate Complementary Voltages -  09/23/10 EDN-Design Ideas Two amplifiers produce voltages that you can use in a variety of applications. __ Circuit Design by Marián Štofka, Slovak University of Technology, Bratislava, Slovakia

  An Audio Amplifier Project (Using the LM386)  -  The LM386 IC has been designed to work with low voltages.  between 4 to 15 volts.  The current taken from the power source or the batteries when standing by, is also quite small, something around 3 mA's.  If you add to these qualities the possibility of changing the amplification power, you realize that the LM386 chip is an attractive circuit to work with. __ Designed by braincambre500 @ yahoo.com

An Audio Equalizer for Communications Use 234 kB PDF file -  This five-band audio equalizer was originally designed for use at a multireciever site   (a voting system hub).  Originally published in the May 1990 QST __ Designed by Robin Humbolt WA4TEM

An Audio Limiter for NBFM use -  This image is of a hard audio limiter used to limit the amount of deviation in an exciter.  After the "knee" the compression ratio is infinite to 1   (hard limiter.)  Smaller amounts of compression ratio can be achieved by inserting resistance between the output of the rectifier, and the DC input of the FET   (gate.)  This circuit can be used ahead of the processing in a standard exciter to add compression, or hard limiting. 
The "R" and "G" are red and green led's.  The op amp can be a 5532, LF-353, or TLO82. __ Designed by Kevin K. Custer  W3KKC

An Audio-Noise-Based Voting -  As hand-held transceivers   (H-Ts) become smaller, and low power, battery conserving operation becomes more popular, the disparity between the transmitting range of a typical 100 watt repeater compared to the repeater accessing range of a typical 1 watt or less H-T becomes more and more apparent.  How often have you found it difficult   (or impossible) to access a repeater with a low power H-T even though you can hear the repeater at full quieting? This can happen even if the repeater is equipped with a high sensitivity, state-of-the-art receiver. __ Designed by Mark Kolber  WB2WHC

An Audio-Video Test Generator -  Use it for testing VCR's, video monitors and the continuity of video cables. __ SiliconChip

An Automatic 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

An Ultra Low Distortion Audio Test Oscillator -  This project was published in the March 2010 issue of the Australian magazine "Amateur Radio", and uses a unique circuit and cheap readily available components to acheive laboratory grade performance.  :-) __ Designed by VK5JST / VK5TR

An ultra-flexible tonestack with clean boost. Schematic, photo & PCB/perfboard layouts. -  The Tonemender is a very flexible, yet simple clean boost with a 3-knob tonestack that allows the user to re-create the classic Fender, Marshall and Vox responses.  We suggest using a TLC2272 for the dual op-amp.  The TLC2272 is rated for low-noise and rail-to-rail output, which will offer the highest possible clean boost and dynamic range.  The NE5532 is another good choice, but a TL072 can also be used with decent results __ Designed by holler @ runoffgroove.Com

AN-60-032  Uses & Advantages of MERA Dual Matched MMIC Amplifiers -  AN-60032 Application Note __ MiniCircuits.com

Analog MIDI Synthesizer -  Schematic only, no circuit description __ Designed by John Simonton

Arduino MIDI interface (Arduino MIDI Drum Kit & Spooky Sound Trigger) -  Here’s a quick project using techniques from this week’s class that turns an Arduino board and a few buttons and piezos into a MIDI drum kit or scary sound trigger.  Hide piezo sensors around the house during your Halloween party to trigger scary sounds when people walk around! __ Designed by todbbot blog

Astatic microphone to Kenwood mic -  Ham RadioSchematic __ Designed by Guy Roels ON6MU

Audio & RF Signal Investigator with LM386-Tool for maintenance of audio equipment -  The Investigator of the audio signal and RF, also known as Signal Tracer is a tool that can not miss on the bench interested in audio equipment, amplifiers either in assembly or maintenance of audio equipment.  Even with simple construction, it is quite necessary to detect defects more quickly.  As a follower of the audio […] __ Designed by Antonio Rodrigues

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, 2000

Audio Amp Based on LM383 8 Watts -  Here is the schematic for an 8 watt audio amp.  This amp can be used as a simple booster, the heart of a more complicated amplifier or used as a guitar amp. __ Designed by Aaron Cake

Audio Amp makes efficient fan controller -  11/09/00 EDN-Design Ideas You can use discrete transistors to vary power to a fan to control its speed.  However, with a simple modification, you can use an audio-amplifier IC to control a fan module  (Figure 1).  The LM4872.   PDF contains multiple circuits, scroll to find the one of interest __ Circuit Design by Wallace Ly, National Semiconductor Corp, Santa Clara, CA

Audio Amp Output Power Limiter -  If you hire out audio equipment, or just don't want the kids to blow up your speakers when you are not home, this is the project for you.  It is a very simple little project, but will protect the speakers from being overdriven.  Any attempt at overdrive will simply cut the amp gain backthe more overdrive, the more the input signal is reduced. __ Designed by Rod Elliott  ESP

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

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