5W Audio Amplifier Circuit - BD139 / BD140

5W Audio Amplifier Circuit based BD139/BD140

The following is the diagram of 5W audio amplifier circuit which built using power transistor BD139 and BD140 as the final gaining process. This small amplifier can be used as general purpose amplifier such as computer amplifier, radio, mp3 player, video player, etc.
5W Audio Amplifier Circuit based BD139/BD140

Input Stage
The input stage consists of Q1 through Q5 and 3 diodes. The differential pair is biased by Q1, R3, R4, D3, D4, and D5. The biased current is set to 1 mA. Q4 and Q5 form a current mirror as the active load for the differential pair, and the output is taken out single-endedly from the collector of Q2. The open loop gain of the input stage is more than 60dB.

Second Stage
Q8 act as a common-emitter amplifier driving the output stage. Current mirror formed by Q6 and Q7 serve both biasing current source and active load for Q8. The open loop gain of the second stage is about 40dB. Q6 and Q7 are mounted together inside the blue tube to provide thermal compensation to each other.

Output Stage
The complimentary pair BD139/140 is biased by D1, D2, and R10. Adjusting the value of R10 can yield the desired quiescent current. R13 and R14 prevent thermal run-away of the complementary pair. DC voltage at the output is always half the power supply.

The feedback network consists of R6, R5, C3 and C4. The overall gain is about the ratio of R6 to R5. C4 provides lead compensation; C3 provides DC-blocking.

Frequency Response
The cut-off frequency is determined at the upper end by C2, R5, and C4, and at the lower end by C1, C3, and C5.

Power supply voltage 12V, 5W for a 4 ohm speaker, 3W for an 8 ohm speaker.

stereo amplifier
power amps
audio amplifier
electronics projects
circuit diagram
class d amplifier
electronic projects
pa amplifier
electronic circuits
stereo amplifiers
amplifier audio
rf amplifier
class a amplifier
stereo amp
audio amplifiers
electronic circuit
class d amp
electronics project
circuit design
amplifier circuit
inverter circuit diagram
electronic project
audio amp
electronics circuits
audio amplifier circuit
circuit design software
amplifier stereo
audio amplifier schematic
ampli audio
electronic circuit design
electronic circuit diagrams
voltage amplifier
power amplifier circuit
simple electronic circuits
stereo amps
led circuit design
class a power amplifier
mosfet power amplifier
audio amplifier board
professional amplifier
amplifier circuit diagram
audio power amplifier design
lm386 audio amplifier
class d audio amplifier
smps circuit diagram
100 watt amplifier
digital audio amplifier
circuit schematics
audio versterker
power amplifier design
class d amplifiers
stereo audio amplifier
op amp buffer
audio amplifier module
digital circuit design
100w amplifier
electronic circuit schematics
circuit drawing
audio amps
amplifier circuits
amplifier design
amplifiers stereo
amplifier class a
circuit designer
simple amplifier circuit
class a amplifiers
amp audio
audio amplifier ic
power amplifier pdf
class d power amplifier
amplifier diagram
amplifier class
audio power amplifier circuit
amplifiers audio
circuit electronic
electronic diagram
circuits diagram
audio amplifier circuit diagram
audio amplifier design
pcb amplifier
ab amplifier
how to design a circuit
electronic amplifier
amplifier schematics
simple audio amplifier
electronics circuit design
potentiometer circuit
circuit drawing software
class d amplifier module
audio amplifier circuits
power amplifier circuit diagram
mosfet amplifier circuit
op amp projects
amplifier 100w
audio amplifier kits
headphone amplifier circuit
voltage amplifier circuit
class c power amplifier
diagram of circuit
simple transistor circuits
simple electronic circuit
simple amplifier
audio circuits
power amplifier schematic
mosfet audio amplifier
audio power amp
power amplifier schematics
class b power amplifier
50 watt amplifier
simple audio amplifier circuit
schematic diagram of power amplifier
rf power amplifier design
amplifier circuit diagrams
electrical circuit design
power amplifier classes
circuit designing
Be the first to comment