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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,Q4andQ2,Q5arecomplementarypairs,theymakecomplementarydarlington 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.
Arcadia Lis
2/6/2017 4:23:55 PM
Marvelous posting.