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DIY Hobby projects, diagram, schematic

Class AB Transistor Power Amplifier Circuit Diagram

electronicecircuits, July 14, 2011August 11, 2023
Class AB Transistor Audio Power Amplifier Circuit

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.

Class AB Transistor  Power Amplifier Circuit schematic

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
R11.5KΩ ¼W
R2150Ω ¼W
R31KΩ ¼W
R40.22Ω 2W
R50.22Ω 2W
R639KΩ ¼W
R71KΩ ¼W
R8120Ω ¼W
R96.8KΩ ¼W
R106.8KΩ ¼W
R1147KΩ ¼W
R1247KΩ ¼W
R132.2KΩ ¼W
R14180KΩ ¼W
R1518KΩ ¼W
C122pF Ceramic
C24.7µF 16V
C3 1000µF 25V
C4100µF 25V
D11N4148
D21N4148
 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 add 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.

Class AB Transistor Audio Power Amplifier CircuitDiscrete Class AB Transistor Audio Power Amplifier

Please send your ideas, which are very important for our success…

Electronic Circuits Amplifier CircuitsPower Amplifier

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Comments (13)

  1. Jack Smith says:
    July 17, 2011 at 12:30 am

    This is a neat and simple circuit. It should be easy to build and will work great.

    Reply
  2. karna says:
    July 25, 2011 at 11:32 am

    thanks

    Reply
  3. yokeswaran says:
    September 9, 2011 at 5:20 pm

    oh!awesome!

    Reply
  4. Sidiney Leonidas says:
    October 8, 2011 at 10:18 pm

    (Portuguese From Brazil) que maravilha esses progetos eu realmente amei são fáceis e praticos

    Reply
  5. Ricardo says:
    February 2, 2012 at 5:04 am

    Sidiney Leonidas :
    (Portuguese From Brazil) que maravilha esses progetos eu realmente amei são fáceis e praticos

    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.

    Reply
  6. shawn says:
    February 23, 2012 at 1:05 pm

    i just want to ask,, where did they got the value of 2 in solving the voltage peak to peak???

    Reply
  7. aru says:
    May 29, 2012 at 1:15 pm

    nice

    Reply
  8. USAMA JAVAID says:
    November 23, 2012 at 11:53 am

    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

    Reply
  9. Bubble says:
    March 24, 2013 at 11:40 pm

    Nice, very nice!

    Reply
  10. h says:
    April 6, 2013 at 12:28 am

    thank you very much

    Reply
  11. zeeshan says:
    October 6, 2013 at 10:46 am

    AS A PRACTICAL

    Reply
  12. justin enriquez says:
    March 17, 2014 at 7:50 am

    is it ok to use 5watts in a resistor .22ohm rather than a 2 watss resistor?

    Reply
  13. auxtics says:
    February 15, 2015 at 3:53 pm

    Hi guys,
    If you are beginner and want to build your own amplifier circuit then visit this link to watch this video and have your complete kit for building your great tda2030a / tda2050 based stereo amplifier.

    https://www.youtube.com/watch?v=Lmi8B26XEG4

    Reply

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