Discrete Class AB Transistor Audio Power Amplifier Circuit Diagram
This is a class AB transistor power amplifier. It is a simple amplifier to build, uses standard parts and is stable and reliable. The entire circuit utilizes commonly available components and may be simply built over a general-purpose board. But this amplifier has very good sound quality.
There are eleven transistors, including four in the output stage. Q1 and Q2 transistor must be between 3 and 5 amperes power transistors. Q4 and Q5 must be between 100mA and 500mA driver transistors. Other transistors are 10mA small driver transistors. Q1, Q4 and Q2, Q5 are complementary pairs, they make complementary darlington pairs.
| PART LIST | |
| R1 | 1.5KΩ ¼W |
| R2 | 150Ω ¼W |
| R3 | 1KΩ ¼W |
| R4 | 0.22Ω 2W |
| R5 | 0.22Ω 2W |
| R6 | 39KΩ ¼W |
| R7 | 1KΩ ¼W |
| R8 | 120Ω ¼W |
| R9 | 6.8KΩ ¼W |
| R10 | 6.8KΩ ¼W |
| R11 | 47KΩ ¼W |
| R12 | 47KΩ ¼W |
| R13 | 2.2KΩ ¼W |
| R14 | 180KΩ ¼W |
| R15 | 18KΩ ¼W |
| C1 | 22pF Ceramic |
| C2 | 4.7µF 16V |
| C3 | 1000µF 25V |
| C4 | 100µF 25V |
| D1 | 1N4148 |
| D2 | 1N4148 |
| Q1 | 2SD313 |
| Q2 | 2SB507 |
| Q3 | 2SA733 |
| Q4 | 2SB560 |
| Q5 | 2SD400 |
| Q6, Q7, Q8, Q9, Q10 | 2SA733 |
| Q11 | 2SD400 |
| LS1 | 4Ω 20W SPEAKER |
Power output of the amplifier
| Supply voltage (Vs) | = 20V |
| Speaker impedance (R) | = 4Ω |
| Peak to peak voltage (Vpp) | = 20-2 =18V |
| Peak voltage | = 9V |
| Maximum output (Pmax) | = 9V2/2R |
| = 81/8 | |
| = 10W |
10W is much enough for the day today home usage.
Amplification of this amplifier (A)
| A | = R6/R13+1 |
| = 39KΩ/2.2KΩ+1 | |
| = 18 |
Volume control can be added to the circuit by connecting a 10KΩ POT in series to the input of the amplifier.
Q1 and Q2 must be kept sufficiently cool, so it is mounted on a suitable heat sink. If you used single heat sink please use insulation between transistors and heat sink.
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Please send your ideas, which are very important for our success…
#1 by h on April 6th, 2013
thank you very much
#2 by Bubble on March 24th, 2013
Nice, very nice!
#3 by USAMA JAVAID on November 23rd, 2012
i am using MS2475 transistor in my design but unfortunately this transistor is not easily available.so any one can tell me about its replacement.i am designing my amplifier in ADS .any one know any thing about it .contact me .thanks
#4 by aru on May 29th, 2012
nice
#5 by shawn on February 23rd, 2012
i just want to ask,, where did they got the value of 2 in solving the voltage peak to peak???
#6 by Ricardo on February 2nd, 2012
Nós do Brasil escrevemos pro”G”eto com “J”! Enfim, o projeto é sim muito bom. Vou montar e avaliar e comparar com o TEA2025B, que é o padrão para caixas de computador. O objetivo é construir um amplificador básico com ótimas respostas para o dia-a-dia na frente do computador.
#7 by Sidiney Leonidas on October 8th, 2011
(Portuguese From Brazil) que maravilha esses progetos eu realmente amei são fáceis e praticos
#8 by yokeswaran on September 9th, 2011
oh!awesome!
#9 by karna on July 25th, 2011
thanks
#10 by Jack Smith on July 17th, 2011
This is a neat and simple circuit. It should be easy to build and will work great.