Audio Stereo Power Amp Circuit

This is a 50 Watt Audio power amplifier circuit based single IC STK4036II. Use heatsink to prevent overheating on the IC. 

The amplifier circuit will give you good quality of sound unexpensive and have low price. 

It is easy we make a power amplifier using only few external components. 

The STK4036II amplifier are will find in enough eponymous stereo amplifiers , but also in enough activety loudspeakers. 

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1V Low Power Stereo Headphone Amplifier with Shutdown MAX9725

The MAX9725A–MAX9725D fixed-gain, stereo headphone amplifiers are ideal for portable equipment where board space is at a premium. The MAX9725E offers the flexibility to adjust the gain with external input and feedback resistors. The MAX9725A–MAX9725E use a unique DirectDrive® architecture to produce a ground-referenced output from a single supply, eliminating the need for large DC-blocking capacitors, saving cost, board space, and component height. Fixed gains of -2V/V (MAX9725A), -1.5V/V (MAX9725B), -1V/V (MAX9725C), and -4V/V (MAX9725D) further reduce external component count. The adjustable gain of the MAX9725E DirectDrive headphone amplifier allows for any gain down to -1V/V using external resistors.

The MAX9725 delivers up to 20mW per channel into a 32Ω load and achieves 0.006% THD+N. An 80dB at 1kHz power-supply rejection ratio (PSRR) allows the MAX9725 to operate from noisy digital supplies without an additional linear regulator. The MAX9725 includes ±8kV ESD protection on the headphone output. Comprehensive click-and-pop circuitry suppresses audible clicks and pops at startup and shutdown. A low-power shutdown mode reduces supply current to 0.6µA (typ).

The MAX9725 operates from a single 0.9V to 1.8V supply, allowing the device to be powered directly from a single AA or AAA battery. The MAX9725 consumes only 2.1mA of supply current, provides short-circuit protection, and is specified over the extended -40°C to +85°C temperature range. The MAX9725 is available in a tiny (1.54mm x 2.02mm x 0.6mm) 12-bump chip-scale package (UCSP™) and a 12-pin thin QFN package (4mm x 4mm x 0.8mm). 

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BA1404 HI FI Stereo FM Transmitter Kit circuit

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Be "On Air" with your own radio station! BA1404 based transmitter is an exciting product that will broadcast high quality stereo signal in 88MHz - 108MHz FM band. It can be connected to any type of stereo audio source such as iPod, Computer, Laptop, CD Player, Walkman, Television, Satellite Receiver, Tape Deck or other stereo system to transmit stereo sound with excellent clarity throughout your home, office, yard or camp ground. Add our 500mW FM / VHF Transmitter Amplifier / Booster for even longer range.

The circuit is based on the popular BA1404 stereo broadcaster IC which contains all the complex circuitry for generating the stereo FM signal. 38 KHz crystal provides a rock solid stability of sub-carrier for stereo signal. PCB includes green solder mask layer for easier soldering and protects wires that do not need soldering.

Kit Components
1x Printed Circuit Board [5 cm x 3.2 cm]
1x BA1404 Stereo FM Transmitter IC
1x 38KHz Crystal Oscillator
1x 3.5T Variable Precision RF Coil
1x 10uH Inductor
4x 10uF/35V Capacitor
4x 1nF Ceramic Capacitor
2x 1nF Mylar Capacitor
1x 220pF Ceramic Capacitor
5x 10pF Ceramic Capacitor
2x 47K Resistor
2x 27K Resistor
1x 150K Resistor
1x 5.6K Resistor
1x 270 Resistor
1x Instructions
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Common car stereo installation problems

If a stereo isnt "playing right", it doesnt mean the unit is broken.

The car stereo has been installed, everything seems to have been done correctly, but there is still a problem. What can be done about it? If a trip to the dealer, or installer is not part of the available solution, or if the job was done by a friend, how should the troubleshooting be done effectively? The answers may lie within this article. Read through the following steps until all sample problems have been corrected or at least removed from possible causes of the issue at hand.

Maintenance and preventive car will help alleviate potential problems with any car stereo. All car stereos need a little maintenance to keep them performing the way they were meant to perform when they were initially installed.

1. All tape heads must be periodically cleaned, and there are kits available for this purpose. The kits may be purchased from auto departments at most chain stores; auto parts stores, or even the dealer if necessary. The kit usually contains an alcohol-based fluid, and cotton-covered swabs that resemble Q-Tips. Use one drop of the liquid on the cotton swab and gently wipe the tape heads for 2-3 seconds. This should be done after every 20 hours of tape play. This will keep road dirt, static electricity, and cigarette tar from gumming up the inner workings of the player.

2. CD players need maintenance as well. Some things to remember about CD players: skipping may be caused by fingerprints, dust, or scratches on the CD inserted into the player, so always be certain the playing surface is smooth and clean. To keep CDs clean, try using CD Saver by CRS. This kit provides a special cloth and a silica-based liquid to clean the surface of the CD. To clean the inside of a CD player, there are CDs that are made expressly for that purpose. Usually, these can be purchased at a dealership or auto parts store.

3. Speakers should be tightened from time to time, as they can attle loose from bumpy roads and general car vibration. Also check for debris on speakers that are mounted on the rear dash, facing upward. Road grit can accumulate, causing rattling and distorted sound. Also this grit and dust can get trapped between the speaker grill and the cone inside; if this is the issue, remove the speaker grill and use a hand-held vacuum cleaner to remove the offending particles. Replace the speaker grill and try the sound again. Also clean the speakers with a damp cloth or an Armor-All cloth and sound should return to normal.

4. If the stereo doesnt seem to be getting power, check the fuse box. Sometimes the fuse will burst from a power surge, or simply burn out. Changing a fuse is an easy task because the fuse box is usually located under the dash or in the glove box. Fuses are very inexpensive and are sold singly or in sets. Simply remove the fuse that is blackened, and match it to one of the new fuses purchased, place the new fuse into the fuse box and the radio should now have power.

5. Sometimes the sound may seem "thin" when the stereo is playing. This could mean that the left/right channel controls are out of phase. Reverse the leads on one speaker. If nothing else, the base response will dramatically increase.

6. Signal loss may occur if the antenna wire becomes loose or unplugged. Check under the cowl or front fender, and in some cars, the glove box. If the wire is connected, try disconnecting it and reconnecting it to be sure there is a clean, tight connection. Also, if this was a home installation, it is prudent to re-check any soldered or taped connections to be certain all wire still have a tight connection. One last thing to check on door speakers, see if the wire has been crimped or cut by the door. Often speaker wires can come loose and be tangled in the door threshold, causing distortion or loss of sound altogether.

7. If options 1-6 have been tried and there is still a problem with sound in a speaker, check to see if there is a short in the wire. If there is an uninsulated stretch of wire, or if the electrical tape has come loose, there could be dirt and loose wiring to blame. Something else to consider is that the uncovered wire may have touched other metal on the car, which is called grounding. In either case, clean the connection, re-twist wires together, and apply fresh electrical tape.

Diagnosing an ailing car stereo is fairly easy, but can be time-consuming. Remember, that 50% of car repair is patience. Go through the steps above in an attempt to identify and rectify the issue the stereo is having. Nothing is more frustrating that to pay a "professional" to do something that could have been done in the driveway at no cost. If all else fails, it might be time to go to a repair facility, or worse-the dealership. Read More

Combine stereo input to one output

Here , I will give a circuit of schemes that are used to combine 2 pieces input or stereo to 1 input mono. Why 2 inputs in to one because, if we need a stereo amplifier we want to become a stronger by combining the two input into one input, so that a higher power output. Actually without any circuit above we can combine stereo amplifier into mono, but the sound output less than the maximum , need for this additional combiner circuit.

Part List =
R1______150K
R2______920R
R3______150K
R4______920R
R5______920R
U1______NE5532

For balance _: R1 / R2=R3 / R4
For balance _: R1 = R3
Gain ______: R5 / R1 = R5 / R3

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14 14W STEREO AMPLIFIER WITH MUTE ST BY

Features

WIDE SUPPLY VOLTAGE RANGE UP TO
±20V
SPLIT SUPPLY
HIGH OUTPUT POWER
14 + 14W @ THD =10%, RL = 8Ω, VS = +16V
NO POP AT TURN-ON/OFF
MUTE (POP FREE)
STAND-BY FEATURE (LOW Iq)
SHORT CIRCUIT PROTECTION TO GND
THERMAL OVERLOAD PROTECTION

Circuit Diagram:

Circuit diagram for 14 + 14W STEREO AMPLIFIER WITH MUTE & ST-BY

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LA4440 Stereo Amplifier Wiring diagram Schematic

LA4440 is a dual channel audio amplifier IC. It can be used in two modes; one is Stereo amplifier and another Bridge amplifier mode. The LA4440 is a monolithic linear IC from Sanyo. Here I give the both schema mode of amplifier using IC LA4440.

When the IC LA4440 is Stereo mode in the schema, its output power is 6w+6w. In stereo mode use two pieces speaker of 2Ωto8Ω.

 LA4440 Stereo Amplifier Circuit Diagram

C10 is filter capacitor used to reduce the ripple of supply voltage. Don’t decrease the value of capacitor C6&C7 less than 100uF, 10v, it may causes of the output at low frequencies goes lower. The pin-6 of LA4440 amplifier schema  is audio input pin; it used in stereo amplifier mode but in bridge mode it is grounded. C8&C9 are polyester film capacitor used to preventing oscillation, and R1&R2 used for the same reason as filter resistor. Though the maximum supply voltage for both schema of amplifier is 18V but we recommend to use a 12V,3A power supply. Use a good quality heat sink with LA4440.

I think here you see little comparison between stereo and bridge amplifier of LA4440. If you want to make this amplifier project, then I recommend you the bridge one. I think it is ideal for a beginner. And I love its wattage rather than Stereo mode. There is also a possibilities as I say, make two copies of schema of bridge amplifier for stereo, it will give you 19w+19w of audio power output.

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Stereo STK013 audio amplifier circuit

On the amplifier circuit using ic STK, the same as my previous posting. However, in the above circuit has 2 inputs and 2 outputs, or commonly called a stereo amplifier. This issue of power amplifier 2 x 18Watt and has impedance 8. To stress that it takes about 35-38Volt.

Component list :
Resistor
R1 =  390K
R2 = 390K
R3 = 220K
R4 = 220K
R5 = 220K
R6 = 220K
R7 = 100R
R8 = 1R
R9 = 9.1K
R10 = 9.1K
R11 = 1R
Capacitor
C1 = 10uF
C2 = 10uF
C3 = 0.47uF
C4 = 0.47uF
C5 = 220uF
C6 = 0.047uF
C7 = 4700uF
C8 = 100uF
C9 = 1000uF
C10 = 100uF
C11 = 4700uF
C12 = 470uF
C13 = 0.047uF
IC
U1 = STK013 Read More