AMPLIFICADOR DE AUDIO DE BAJA TENSION APPLICATIONS:
The first problem that occurs when performing a
notebook computer, for example, paging, is the amplified audio signal
with low voltage.
This can be solved using this as
amplifier circuit can be powered from 3 and 12 VDC,
varying the output power (a higher voltage, more power).
has an input impedance of 50 KOhms and
distortion of 0.2%.
LIST OF COMPONENTS: CAPACITORS
:
C1 = 10 uF 16 V (electrolytic)
C2 = 220 uF 16 V (electrolytic)
SEMICONDUCTORS:
IC1 = LM 386 N-1 / N-3
MISCELLANEOUS: P1 = potentiometer
of 22 KOhms logarithmic (not supplied)
OPERATING PRINCIPLE:
This amplifier is based on the use of an integrated circuit type LM 386,
which is designed for use as an amplifier, which have
low voltage supply. The gain of this IC is internally set to 20 (26 dB) and
only needs for proper functioning of the capacitor C2 which decouples the output
to obtain an adequate signal to excite the speaker and in turn prevent power
continues to reach and damage the voice coil.
In our case to increase the amplifier gain to 200 times (46 db)
place between pins 1 and 8 of 10 uF capacitor, with this short for Altena
current resistance of 1.35 K (internal circuit integrated), which acts as gain control
LM386.
inputs of this circuit are referred ground, and the output is adjusted automatically
half the supply voltage.
circuit consumption at rest (0V input voltage) is only 24 mW
when it works with 6 volts, making it the ideal board for
work with batteries.
NOTES:
If the gain provided by the circuit (200 times), is greater
to the needy, it should be reduced by removing C1.
If you need more output power can be replaced by an integrated circuit
LM 386 N-4 and increase the supply voltage up to 20 V
thus obtained an output power of 1.5 W.
Keep in mind, in this case, the minimum supply voltage Vcc rises to 4.5
.
If the picture does not look right, click on it and see larger
ASSEMBLY NOTES:
If you want you can mount the 2 IC in a socket for integrated circuits
type DIL 16 ( 8 legs on each side)
is recommended to wire inputs and
potentiometers wired mesh.
Connect, in each case, the mesh of the platelet mass.
In case of background noise, place a capacitor of 100 nF between the terminals
supply.
TECHNICAL FEATURES: POWER SUPPLY VOLTAGE
3 to 12 VOLTS CURRENT
REST (6 V) 4 mA
BANDA WIDTH
300 KHz IMPEDANCE
50 KOhms 0.2%
HARMONIC DISTORTION OUTPUT
(6 V) 0.3 W
OUTPUT POWER (9 V) 0.6
OUTPUT
W (12 V) 0.75 W
LOAD IMPEDANCE
8 to 16 ohms maximum power consumption (12 VDC) 60 mA
beginners 
