AUDIO FREQUENCY CIRCUIT

Car Amplifier for MP3

noreply@blogger.com (Go2Media) — Fri, 10 Apr 2009 10:55:00 +0000

Here's schematic diagram of an active loudspeaker. The LF353 is going to split audio signal into three bands. SANYO'S LA47536 is going to amplify these signals. In stereo mode, we shall have the action of eight high speakers who are going to create a very important sound pressure.

Three Band Active Tone Control
These devices are low cost, high speed, dual JFET input operational amplifiers with an internally trimmed input offset voltage (BI-FET II technology). They require low supply current yet maintain a large gain band width product and fast slew rate. In addition, well matched high voltage JFET input devices provide very low input bias and offset currents.

The LF353 is pin compatible with the standard LM1558 allowing designers to immediately upgrade e the overall performance of existing LM1558 and LM358 designs. These amplifiers may be used in applications such as high speed integrators, fast D/A converters, sample and hold circuits and many other circuits requiring low input offset voltage, low input bias current, high input impedance, high slew rate and wide bandwidth. The devices also exhibit low noise and offset voltage drift.

Power Amplifier

When the amplifier is installed behind in the suitcase, we shall need a switch works stop. The LA47536 possesses a function stand by in it pin4. This pine require a small tension superior to 2V in start up the amplifier. Transistor Q1 and Q2 makes the function of walking stop for distance. When the driver activates the left indicator, either light the back fires or press on the brake , lamps rear ignite driving Q2 who he even made to drive Q1 who applies a tension > 2V on it pin4. Overview

LA47536 Four-Channel 45 W BTL Car Audio Power Amplifier
The LA47536 is a 4-channel BTL power amplifier IC developed for use in car audio systems. The output stage features

- A pure complimentary structure that uses V-PNP transistors on the high side and NPN transistors on the low side to provide high power and superb audio quality.

- The LA47536 includes almost all the functions required for car audio use, including a standby switch, a muting function, and each protection circuit. It also provides a self-diagnosis function (output offset detection).

Printed Circuit Boards

Article Source: Visit Site of 150W MP3 Car Amplifier

Audio Preamplifier with Tone Control

noreply@blogger.com (Go2Media) — Sat, 25 Oct 2008 03:16:00 +0000

The Audio Preamplifier Circuit sensitivity and overload margin were designed to cope with most modern music programme sources like CD players, Tape recorders, iPods, Computer audio outputs, Tuners etc. The source selecting switches and input connectors are not shown and their number and arrangement are left to the constructor's choice.

To obtain a very high input overload margin of the audio preamplifier, the volume control was placed at the preamplifier input. After a unity gain, impedance converter stage (Q1) a negative-feedback Baxandall-type Bass and Treble tone control stage was added. As this stage must provide some gain (about 5.6 times) a very low noise, "bootstrapped" two-transistors circuitry with FET-input was implemented. This stage features also excellent THD figures up to 4V RMS output and a low output impedance, necessary to drive properly the Mini-MosFet Power Amplifier, but can also be used for other purposes.

Audio Preamplifier Parts List:

R1=220K 1/4W Resistor
R2=100K 1/4W Resistor
R3=2K7 1/4W Resistor
R4,R5=8K2 1/4W Resistors
R6=4K7 1/4W Resistor
R7,R8,R13=2K2 1/4W Resistors
R9=2M2 1/4W Resistor
R10,R11=47K 1/4W Resistor
R12=33K 1/4W Resistor
R14=470R 1/4W Resistor
R15=10K 1/4W Resistor
R16=3K3 1/4W Resistor (See Notes)

C1,C2,C9=470nF 63V Polyester Capacitors
C3,C4=47nF 63V Polyester Capacitors
C5,C6=6n8 63V Polyester Capacitors
C7=10µF 63V Electrolytic Capacitor
C8,C10=22µF 25V Electrolytic Capacitors
C11=470µF 25V Electrolytic Capacitor (See Notes)

Q1,Q3=BC550C 45V 100mA Low noise High gain NPN Transistors
Q2=2N3819 General-purpose N-Channel FET

Mosfet Audio Power Amplifier 18W

noreply@blogger.com (Go2Media) — Sat, 25 Oct 2008 02:33:00 +0000

This audio project is designing an audio amplifier capable of delivering a decent output power with a minimum parts count, without sacrificing quality.

This audio amplifier circuit employs only three transistors and a handful of resistors and capacitors in a shunt feedback configuration but can deliver more than 18W into 8 Ohm with <0.08% THD @ 1KHz at the onset of clipping (0.04% @ 1W - 1KHz and 0.02% @ 1W - 10KHz) and up to 30W into a 4 Ohm load.

To obtain such a performance and to ensure overall stability of this very simple circuitry, a suitable regulated dc power supply is mandatory. This is not a snag because it also helps in keeping noise and hum of the preamp to very low levels and guarantees a predictable output power into different load impedances. Finally, as the audio amplifier requires only a single rail supply, a very good dc voltage regulator capable of supplying more than 2 Amps @ 40V can be implemented with a few parts also.

Audio power amplifier Parts List:

R1=2K2 1/4W Resistor
R2=27K 1/4W Resistor
R3,R4=2K2 1/2W Trimmers Cermet or Carbon (or 2K)
R5=100R 1/4W Resistor
R6=1K 1/4W Resistor R7,
R8=330R 1/4W Resistors

C1=22µF 25V Electrolytic Capacitor
C2=47pF 63V Polystyrene or Ceramic Capacitor
C3,C4=100µF 50V Electrolytic Capacitors
C5=2200µF 50V Electrolytic Capacitor

Q1=BC550C 45V 100mA Low noise High gain NPN Transistor
Q2=IRF530 100V 14A N-Channel Hexfet Transistor (or MTP12N10)
Q3=IRF9530 100V 12A P-Channel Hexfet Transistor (or MTP12P10)

Source:Audio Amplifier with MOSFET

Headphone Amplifier

noreply@blogger.com (Go2Media) — Thu, 10 Jul 2008 19:24:00 +0000

This electronic circuit is a high quality headphone amplifier. It's no need for a preamplifier. This circuit equipped with a symetrical power supply.

Amplifier parts list:

P1 - 22K Log.Potentiometer (Dual-gang for stereo)
R1 - 560R 1/4W Resistor
R2,R3 - 10K 1/4W Resistors
R4 - 12K 1/4W Resistor
R5,R6 - 2R2 1/4W Resistor
R7 - 22R 1/2W Resistor
C1 - 1µF 63V Polyester Capacitor
C2,C3,C4 - 100µF 25V Electrolytic Capacitors
C5 - 22pF 63V Polystyrene or Ceramic Capacitor
C6 - 22µF 25V Electrolytic Capacitor
IC1 - LM833 or NE5532 Low noise Dual Op-amp
Q1,Q3 - BC337 45V 800mA NPN Transistors
Q2,Q4 - BC327 45V 800mA PNP Transistors
J1 - RCA audio input socket

Power supply parts List:

R8 - 2K2 1/4W Resistor
C7,C8 - 2200µF 25V Electrolytic Capacitors
D1 - 100V 1A Diode bridge
D2 - 5mm. or 3mm. Red LED
IC2 - 7815 15V 1A Positive voltage regulator IC
IC3 - 7915 15V 1A Negative voltage regulator IC
T1 - 220V Primary, 15 + 15V Secondary 5VA Mains transformer
PL1 - Male Mains plug
SW1 - SPST Mains switch

Notes:

Can be directly connected to CD players, tuners and tape recorders.
Tested with several headphone models of different impedance: 32, 100, 245, 300, 600 & 2000 Ohm.
Old 8 Ohm impedance headphones can be also driven, but these obsolete devices are not recommended.
Schematic shows left channel and power supply (common to both channels).
Numbers in parentheses show IC1 right channel pin connections.
A correct grounding is very important to eliminate hum and ground loops. Connect to the same point the ground sides of J1, P1, C2, C3 & C4. Then connect separately the input and output grounds to the power supply ground.

Source: Headphone Amplifier

Precision Audio Millivoltmeter

noreply@blogger.com (Go2Media) — Thu, 10 Jul 2008 19:17:00 +0000

This electronic circuit is audio milivolt meter. It measures 10mV to 50Volt RMS in eight ranges. Simply connect to your Avo-meter set to 50µA range. You should measure your audio preamplifier and low watt audio amplifiers with this one.

Parts:

R1 - 909K 1/2W 1% Metal Oxide Resistor
R2 - 90K9 1/2W 1% Metal Oxide Resistor
R3 - 9K09 1/2W 1% Metal Oxide Resistor
R4 - 1K01 1/2W 1% Metal Oxide Resistor
R5 - 100K 1/4W Resistor
R6 - 2M2 1/4W Resistor
R7 - 82K 1/4W Resistor
R8 - 12K 1/4W Resistor
R9 - 1K2 1/4W Resistor
R10 - 3K3 1/4W Resistor
R11 - 200R 1/2W Trimmer Cermet
C1 - 330nF 63V Polyester Capacitor
C2,C3 - 100µF 25V Electrolytic Capacitor
C4 - 220µF 25V Electrolytic Capacitor
C5 - 33pF 63V Polystyrene Capacitor
C6 - 2µ2 63V Electrolytic Capacitor
D1-D4 - 1N4148 75V 150mA Diodes
IC1 - CA3140 Op-amp
IC2 - CA3130 Op-amp
SW1 - 2 Holes 5 ways rotary switch
SW2 - SPDT switch
J1 - RCA audio input socket
J2,J3 - 4mm. output sockets
B1 - 9V PP3 Battery
Clip for PP3 Battery

Notes:

Connect J2 and J3 to an Avo-meter set to 50µA range:
Switching SW2 the four input ranges will be multiplied by 5
Total fsd ranges are: 10mV, 50mV, 100mV, 500mV, 1V, 5V, 10V, 50V
Set R11 to read 1V in the 1V range, with a sine wave input of 1V @ 1KHz
Compare the reading with that of another known precision Millivoltmeter or with an oscilloscope.
The oscilloscope reading must be a sinewave of 2.828V peak to peak amplitude
Frequency response is flat in the 20Hz-20KHz range
If you have difficulties in finding resistor values for R1, R2, R3 & R4, you can use the following trick:

R1 = 10M + 1M in parallel
R2 = 1M + 100K in parallel
R3 = 100K + 10K in parallel
R4 = 1K2 + 6K8 in parallel
All resistors 1/4W 1% tolerance

Source: Precision Audio Millivoltmeter

Stereo Preamplifier with Bass-boost

noreply@blogger.com (Go2Media) — Thu, 10 Jul 2008 19:09:00 +0000

This preamplifier circuit was designed to cope with CD players, tuners, tape recorders etc., providing an ac voltage gain of 4, in order to drive less sensitive power amplifiers. As modern Hi-Fi home equipment is frequently fitted with small loudspeaker cabinets, the bass frequency range is rather sacrificed. This circuit features also a bass-boost, in order to overcome this problem. You can use a variable resistor to set the bass-boost from 0 to a maximum of +16dB @ 30Hz. If a fixed, maximum boost value is needed, the variable resistor can be omitted and substituted by a switch.

Parts List:

P1 - 10K   Log.Potentiometer (Dual-gang for stereo)
P2 - 100K   Log.Potentiometer (Dual-gang for stereo) (See Notes)
R1,R2 - 100K   1/4W Resistors
R3,R6 - 15K   1/4W Resistors
R4 - 10K   1/4W Resistor
R5 - 22K   1/4W Resistor
R7 - 1K   1/4W Resistor
R8 - 560R   1/4W Resistor
C1,C2,C5 - 2µ2   63V Electrolytic Capacitors
C3 - 470µF   35V Electrolytic Capacitor
C4 - 1µF   63V Polyester Capacitor
C6 - 47nF   63V Polyester Capacitor
C7 - 22µF   25V Electrolytic Capacitor
IC1 - TL072  Dual BIFET Op-Amp
SW1 - DPST  Switch (Optional, see Notes)

Notes:

Schematic shows left channel only, but R1, R2, R3 and C1, C2, C3 are common to both channels.
For stereo operation P1, P2 (or SW1), R4, R5, R6, R7, R8 and C4, C5, C6, C7 must be doubled.
Numbers in parentheses show IC1 right channel pin connections.
A log type for P2 ensures a more linear regulation of bass-boost.
Needing a simple boost-in boost-out operation, P2 must be omitted and SW1 added as shown in the diagram.
For stereo operation SW1 must be a DPST type.
Please note that, using SW1, the boost is on when the switch is open, and off when the switch is closed.

Source: Stereo Preamplifier with Bass-boost

Stereo PreAmplifier With Tone Control

noreply@blogger.com (Go2Media) — Thu, 26 Jun 2008 10:54:00 +0000

This is a preamplifier and tone control unit which will make a useful addition to any of our power amplifier circuits. It is extremely easy to construct due to the use of a special IC, The Philips TDA1524A.

Because it uses voltage control, linear single gang pots can be used , which lowers the costs and reduces tracking errors. It also allows for control by switches or microprocessor if desired.

Specification:

D.C. Input : 15V DC supply or 12V
DC battery. 50 mA min.
Maximum output : 3 V RMS
Maximum input : 300 mV, G = 20 dB 3V RMS, G = 0dB
Input Z 10 k ohm
Output Z 300 ohm Frequency resp. : 50 kHz + / – 1 dB
THD at 1kHz : 0.1 % at 1V output S/N ratio : 80 dB, G = 0 dB
Bass boost/cut ~ 15 dB at 50 Hz
Treble boost/cut ~ 15 dB at 15 kHz

Go here for IC TDA1524A Datasheet - Original Audio Kit

USB Powered Audio Power Amplifier for PC

noreply@blogger.com (Go2Media) — Thu, 26 Jun 2008 10:41:00 +0000

This audio power amplifier might be good solution to all of those who have PC with integrated sound card into motherboard. The main problem is that outputs of such sound cards are for active acoustic systems, this means that speakers must have power amplifier built in. If you decide to connect a headphones sometimes it might be not enough to provide required sound level.

If you are an electronics amateur, you can solve this very easily. You may build your simple power amplifier by using well known Philips operational amplifiers. Lets say we use TDA7053 amplifier. The TDA7053 is an integrated class-B stereo power amplifier in a 16-lead dual-in-line (DIL) plastic package. Which requires minimal amount of external parts. (IC Datasheet)

Low Voltage Audio Power Amplifier LM386

noreply@blogger.com (Go2Media) — Tue, 24 Jun 2008 03:44:00 +0000

The LM386 is a power amplifier designed for use in low voltage consumer applications. The gain is internally set to 20 to keep external part count low, but the addition of an external resistor and capacitor between pins 1 and 8 will increase the gain to any value from 20 to 200.

Features:

Battery operation
Minimum external parts
Wide supply voltage range: 4V-12V or 5V-18V
Low quiescent current drain: 4mA
Voltage gains from 20 to 200
Ground referenced input
Self-centering output quiescent voltage
Low distortion: 0.2% (AV = 20, VS = 6V, RL = 8Ohm, PO = 125mW, f = 1kHz)
Available in 8 pin MSOP package

The inputs are ground referenced while the output automatically biases to one-half the supply voltage. The quiescent power drain is only 24 milliwatts when operating from a 6 volt supply, making the LM386 ideal for battery operation. (datasheet)

20W Audio Power Amplifier LM1875

noreply@blogger.com (Go2Media) — Tue, 24 Jun 2008 03:19:00 +0000

The LM1875 is a monolithic audio power amplifier offering very low distortion and high quality performance for consumer audio applications.

Fetaures:

Up to 30 watts output power
AVO typically 90 dB
Low distortion: 0.015%, 1 kHz, 20 W
Wide power bandwidth: 70 kHz
Protection for AC and DC short circuits to ground
Thermal protection with parole circuit
High current capability: 4A
Wide supply range 16V-60V
Internal output protection diodes
94 dB ripple rejection
Plastic power package TO-220

The LM1875 delivers 20 watts into a 4 or 8 load on ±25V supplies. Using an 8 load and ±30V supplies, over 30 watts of power may be delivered. The amplifier is designed to operate with a minimum of external components. Device overload protection consists of both internal current limit and thermal shutdown.

The LM1875 design takes advantage of advanced circuit techniques and processing to achieve extremely low distortion levels even at high output power levels. Other outstanding features include high gain, fast slew rate and a wide power bandwidth, large output voltage swing, high current capability, and a very wide supply range. The amplifier is internally compensated and stable for gains of 10 or greater. (datasheet)

General Purpose 2 x 2Watts Audio Power Amplifier

noreply@blogger.com (Go2Media) — Sun, 15 Jun 2008 14:08:00 +0000

A general purpose audio power amplifier is a must have for the electronics amateur. It's not a good thing to use your HiFi set for an experiment, when there's a risk of blowing it's transistor out. Amplifier for your experiments should be simple in construction, durable, and easy to repair. Also a portable, low power consumpting, battery operateable one will be suitable.

Taking the considerations above, I gave you the PCB design for the TBA820M based amplifier. It is rated for 2Watts of RMS power output (16W PMPO) but gives even two times more if you cool it well by some tricks. I've been using this circuit for over ten years and personally still surprised by it's durability, thinking of how many short circuits and overdrives it is subjected.

I did not know if TBA820M is still manufactured (my IC's are made by SGS-Thomson), so it may be obsolete in your country and hard to find. But if you find it in a local electronics shop, purchase a dozen, they will worth it. A simplified, scaled down version of this circuit may be used anywhere, where a power amplifier is needed.

Technical datas:

Supply voltage : 3 to 16 Volts
Load impedance : 4 TO 16 Ohms
Power output : 2 Watts RMS
Gain : 40 dB (x100)

Here is the PCB design for two channels on it. I tried to make it as small as possible but volume control potentiometer took a lot of space. In a special design, area it's occupied may be omitted. Also usage of high quality small sized capacitors may help you to reduce the circuit size further.

PCB design for 2 x 2Watts power amplifier

After the etching process of the PCB, solder all of the components on. Please use IC sockets in order to be able to change TBA820M's if you blow them out somehow. Here is a photo of the completed circuit, ready to serve for years.

Completed amplifier

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noreply@blogger.com (Go2Media) — Tue, 10 Jun 2008 05:12:00 +0000

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