Tuesday, February 8, 2022

440W Class AB Power Amplifier using Mosfet IRFP9240 and IRFP240 Transistors with PCB


Fig. 1 - 440W Class AB Power Amplifier using Mosfet IRFP9240 and IRFP240 Transistors with PCB


This is a high performance power amplifier, which despite its simplicity in construction, in the tests performed, it presented parameters with great results, very close to what we call a HI-FI amplifier.

The Circuit Works

The complexity of the circuit is at an advanced level, it is not recommended for those who don't have experience in electronics and in assembling amplifier circuits, you must have minimal knowledge at an advanced level to assemble this type of power amplifier.

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The circuit diagram of the power amplifier is shown in Figure 2 below. It uses 8 output Mosfet power transistors, 4 transistors for the positive cycle and 4 transistors for the negative cycle. 

Fig. 2 - Schematic diagram 440W Class AB Power Amplifier using Mosfet IRFP9240 and IRFP240 Transistors 

The input circuit consists of a TL431 Op-Amp, it is used as a feed-forward preamplifier for the driver circuit units that produce a primary voltage gain at the output stage.

The circuit is divided into 2 identical half-cycles: one side for the positive half-wave of the signal fed through driver transistor Q1 NPN BD139, which feeds the output transistors (Q3, Q5, Q7, Q9 ) P-Channel IRFP9240, the other side for the negative half-wave of the signal fed through driver transistor Q2 PNP BD140, which feeds the output transistors (Q4, Q6, Q8, Q10) N-Channel IRFP240.

The Power Supply 

The power supply is of the symmetrical type, with a supply voltage of +55V | 0V | -55V, with a current of 10 Amperes, with good filtering. 

In Figure 3 below, we have a suggestion for a power supply that we use in our projects. In this article, besides having the schematic diagram with the Printed Circuit Board, you will understand how to easily calculate your own Power Supply, with the desired voltage.

You can in the link below:

Fig. 3 - Symmetrical Power Supply for Power Amplifiers

Components List

  • Semiconductors
    • U1 .......................... TL071 Integrated Circuit
    • Q1 .......................... BD139 NPN Transistor
    • Q2 .......................... BD140 PNP Transistor
    • Q3, Q4, Q5, Q6 ..... IRFP9240 Mosfet Transistor
    • Q7, Q8, Q9, Q10 ... IRFP240 Mosfet Transistor
    • D1, D2 ................... 1N4744 15V Zener diode
      D3, D4 ................... 1N4148 diode

  • Resistor
    • R1, R33 ................. 47KΩ (yellow, violet, orange, gold
    • R2 .......................... 1KΩ  (brown, black, red, gold)
    • R3, R4 .................... 2K7Ω (red, violet, red, gold)
    • R5, R6 .................... 2KΩ (red, black, red, gold)
    • R7 ........................... 6k8Ω Trimpot 
    • R8, R9 .................... 22KΩ (red, red, orange, gold)
    • R10, R11 ................ 33Ω (orange, orange, black, gold)
    • R12, R13 ................ 220Ω (red, red, brown, gold)
    • R14, R5 .................. 820Ω ( grey, red, brown, gold)
    • R16 ......................... 3.3Ω (orange, orange, gold, gold)
    • R17, R18, R21, R22, R25, R26, R29, R30 .... 39Ω (orange, white, black, gold)
    • R19, R20, R23, R24, R27, R28, R31, R32 .... 5W 0.33Ω (orange, orange, silver, gold)
  • Capacitor
    • C1, C5 .................... 100pF Ceramic Capacitor
    • C2, C6, C7 .............. 1uF Ceramic Capacitor
    • C3, C4, C9, C10 ..... 470uF / 65V Electrolytic Capacitor 
    • C8 ........................... 100nF Ceramic Capacitor


  • Miscellaneous 
    • P1 .......... 2-pin PCB soldering terminal blocks
    • P2 .......... 3-pin PCB soldering terminal blocks
    • Others .... Printed Circuit Board, heat sink, wires, etc.


We are offering the PCB - Printed Circuit Board, in GERBER, PDF and PNG files, for you who want to do the most optimized assembly, either at home, or if you prefer in a company that develops the board, you can is downloading and make the files in the Download option below.
Fig. 3 - 440W Class AB Power Amplifier using Mosfet IRFP9240 and IRFP240 Transistors

Files to Download, Direct Link:

Click on the link beside: GERBER, PDF and PNG files

If you have any questions, suggestions or corrections, please leave them in the comments and we will answer them soon.

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My Best Regards!!!


10 comments:

  1. Hi can you mention the resistor wattage details

    ReplyDelete
    Replies
    1. Hello SRIRAM!

      All resistors are 1/8W, except resistors R19, R20, R23, R24, R27, R28, R31, R32. which are 5W.
      My best Regards!

      Delete
  2. Hi!,
    I orded some pcb's via pcbway. Just finished populating them. I can't really makeup out of the schematics where the V+ and V- should be connected on the pcb. Should the V+ be on the top left corner of the pcb?

    ReplyDelete
    Replies
    1. Hello @MARIUSM
      The +Vdc is the one that sits next to the bolt support hole, you looking facing the connector, and the left side. My regards.

      Delete
  3. Hi!, I ordered pcb's via pcbway. Just finished populating them. If I plug in the power connector the mosfest gates keep shorting themselfs, if I unplug the powercable the short is gone. Any idea why that happens?

    ReplyDelete
    Replies
    1. Hello @MARIUSM,
      This can be numerous problems, but on the part, check carefully if there is any inverted component, if there is any component in short, if the connections are correct, or if it has any component that is not original.
      My best regards.

      Delete
  4. Hi!, to what value should is ajust the potentiometer?

    ReplyDelete
    Replies
    1. Hello @MARIUSM,
      The Bias setting should be measured with the multimeter on the transistor Q1 between base and emitter, a voltage of approximately 600mV.
      My best Regards!

      Delete
  5. Hi, thanks for the information! I didn't knew the commenting took this long, apologies for the many comments. The potentiometer I used wasn't precise enough. I checked the signal with a function generator and a oscilloscope. Distortion can happen very quick in this design. Also the footprint of the 470uf elco sitting right after the main power lines, is quite small. Elco's with a voltage rating of 63V are bigger. Also the drill holes in the corner of the pcb are very tiny. Besides that does it sound very clean.

    ReplyDelete
    Replies
    1. Hello @MARIUSM

      We greatly appreciate your feedback!
      Messages often take time, due to hundreds of messages of "Span messages", which they send with an associated link.
      Unfortunately, this disturbs others who need to communicate with us.

      Every day, we are trying to improve our website, which has been growing a lot.
      Don't worry, feel free to send messages, and we can discuss matters pertaining to the circuits.
      Best Regards!

      Delete