The Audio Circuit

Thursday, January 31, 2008

MB audio IC

MB3722
2x5.8 AUDIO AMPLIFIER

MB3730
12W AUDIO AMPLIFIER

MB3731
18W AUDIO AMPLIFIER

Monday, January 28, 2008

AUDIO PREAMP

5 BAND GRAPHIC EQUALIZER
LA 3600

STEREO TAPE PREAMPLIFIER
LA 3160

2 CHANEL TAPE HEAD PREAMPLIFIER
LA3161

EQUALIZER AMPLIFIER
LA3210

2 CHANEL EQUALIZER
LA 3220

MICROPHONE PREAMPLIFIER
LA3225T/LA3226T

Sunday, January 27, 2008

D-MOS POWER AMPLIFIER (TDA7294)

PIN CONECTION

SCHEMATIC DIAGRAM

ELECTRICAL CHARACTERISTIC (Refer to the test Circuit)

Vs = -35V, RL = 8W, GV = 30db,
Rg = 50W, Tamb = 25ºC, F=1kHz

http://www.st.com/stonline/

200W Power Amplifier

This amplifier for universal usability, such as for home audio, seminar and for games (PS3 games, Xbox and others)

Schematic Diagram

number	name
Transistors
12x	Q1, Q2, Q5, Q7, Q9, Q10	MPSA 06
10x	Q3, Q4, Q6, Q8, Q11	MPSA 56
4x	Q13, Q14	2N 3439
4x	Q12, Q15	2N 5416
2x	Q16	MJE 15030
2x	Q17	MJE 15031
4x	Q18, Q20	MJ 15003
4x	Q19, Q21	MJ 15004
Diodes
12x	D1, D2, D3, D4, D11, D12	1N4007
12x	D5, D6, D7, D8, D9, D10	1N4148
8x (15x)	D13, D14, D15, D16	20 V Zener +5% tolerance, 0.5W
Capacitors
2x	C1	390 pF mica
14x	C2, C3, C15, C16, C23, C24, C25	100nF/100V film
8x	C7, C12, C17, C18	100nF/50V film
12x	C4, C5, C13, C14, C21, C22	100uF/63V radial electrolytic
2x (4x)	C6a, C6b	220uF/16V bi-polar electrolytic (4x 330uF/16V)
2x	C8	180pF mica
2x	C9	47pF mica
4x	C10, C11	10pF mica
4x	C19, C20	10nF/50V film
Rezistors
All resistors are 1% carbonic or metalised 0,5W if not noted otherwise
2x	R1	20 kohm
2x	R2	2 kohm
16x	R3, R4, R5, R6, R7, R8, R9, R10	300 ohm
6x	R11, R12, R27	1.2 kohm
4x	R13, R14	2.2 kohm
4x	R15, R16	12 kohm
4x	R17, R18	11 kohm
2x	R19	1.1 kohm
2x	R20	22 kohm
4x	R21, R22	30 ohm
4x	R23, R24	360 ohm
4x	R25, R26	1 kohm
4x	R28, R29	270 ohm
4x	R30, R31	3.9 kohm 1/2 W
6x	R32, R33, R51	82 ohm
4x	R34, R35	330 ohm
2x	R36	220 ohm
8x	R37, R38, R39, R40	680 ohm
8x	R41, R42, R43, R44	10 ohm 1/2 W
8x	R45, R46, R47, R48	0.33 ohm 5 W wire-wound
4x	R49, R50	10 ohm, 2 W
Other
2x	P1	2 kohm more turn cermet trimmer
1x	T1	Toroid power transformer SEC 2x40V AC 300W
8x	C1P, C2P	4700uF/63V (6x 6800uF/63V)
8x	C3P	100nF/200V
1x	D1P	Bridge rectifier 35A/200V
5x		Fuse casing
1x	F1	Fuse 3.15A T
4x	F2, F3, F4, F5	Fuse 5A F
8x		Insulative bed under transistors + screw insulatives 16x
20x		Solder eye M4
2m		Shrinking spaghetti 4mm

Tuesday, January 15, 2008

150W MP3 Car Amplifier

mp3 player mp3 song
Block Diagaram

Three Band Active Tone Control

Click Image for Enlarge

Description :
LF353 Wide Bandwidth Dual JFET Input Operational Amplifier
General Description
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. (National Semiconductor)

Features :
Internally trimmed offset voltage: 10 mV
Low input bias current: 50pA
Low input noise voltage: 25 nV
Low input noise current: 0.01 pA
Wide gain bandwidth: 4 MHz
High slew rate: 13 V/us
Low supply current: 3.6 m
High input impedance: 1012.
Low total harmonic distortion : <>
Low 1/f noise corner: 50 Hz
Fast settling time to 0.01%: 2 us

Power Amplifier

Click Image for Enlarge

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). (Sanyo)

Functional Description
1. Standby Switch Function (pin 4)
The pin 4 threshold voltage is set to be 2 VBE. When Vst is 2.0V or higher, the amplifier will be on, and when Vst, is 0.7V or lower, the amplifier will be off. Note that pin 4 requires an operating current of at least 40uA.

2. Muting Function
The IC is set to the muted state by setting pin 22 to the ground potential. In this state, the audio output is muted. The time constant with which the muting function operates is set by an external RC circuit, and this time constant influences the pop noise that occurs when the amplifier is turned on or off.
The muting on and off times due to the recommended external component values (R=10k, C=3.3uF) are as follows.
Muting on time: 50ms
Muting off time: 20ms

3. Self-Diagnosis Function (Speaker burnout prevention)
During steady state operation, the LA47536 detects, internally, whether or not an abnormal amplifier output offset has occurred, and outputs this signal from pin 25. Applications can prevent speaker burnout and other problems by having the system microcontroller detect this pin 25 output signal and control either the standby state or the power supply. (An abnormal output offset may be caused by, for example, input capacitor leakage current.) The pin 25 signal is turned off by setting pin 1 to the ground potential.

4. Oscillator Stability
In some cases, parasitic oscillations may be induced by the PCB layout. This oscillation can be eliminated by adding the components listed below. Note that the optimal capacitor value must be verified by testing in the actual mounted state in the end product. Connect a capacitor and resistor (0.1uF and 2.2) in series between each output pin and ground.

5. Audio Quality (Low band)
The frequency characteristics in the low frequencies can be improved by making the capacitance of the input capacitors variable. The recommended capacitance is 2.2uF and smaller.

6. Protection Circuits
Do not ground the outputs with the STBY voltage at around 1.4V. Also, do not turn the IC off in the grounded state with a time constant provided for the STBY voltage.

7. Pop Noise
Although the LA47536 includes an pop noise prevention circuit, pop noise can be reduced even further by using the muting function as well. Activate the muting function at the same time as power is applied. Then, after the output DC potential has stabilized, turn off the muting function. When turning the amplifier off, first turn on the muting function and then turn off the power supply. These two methods are effective at minimizing pop noise.

Pre Amplifier PCB