DIY Class D Audio Amplifier

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About: Awesome Electronics Tutorials, Projects and How To´s

In this project I will show you why a class AB amplifier is pretty inefficient and how a class D amplifier on the other hand improves this efficiency. At the end I will show you how we can apply the theory of operation of a class D amp to a couple of common components in order to create our own DIY class D audio amp. Let's get started!

Step 1: Watch the Video!

The video gives you all the information you need to build your own class D audio amp. During the next steps however I will present you some additional information to make the project even simpler.

Step 2: Order Your Components!

Here you can find a parts list with example sellers:

Ebay:

1x 3.5mm Audio Jack: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

1x 10kΩ Potentiometer: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

1x LM393 Comparator: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

1x TLC555 Timer: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

1x 74HC04 Inverter: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

1x IR2113 MOSFET Driver: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

2x IRLZ44N MOSFET: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

1x 7805 Voltage Regulator: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

1x 7812 Voltage Regulator: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

2x PCB Terminal: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

3x 47µF, 1x 22µF Capacitor: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

7x 220nF Capacitor: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

3x UF4007 Diode: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

2x 10kΩ, 2x 10Ω, 1x 2kΩ Resistor: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

2x 33µH Inductor: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

Amazon.com:

1x 3.5mm Audio Jack: http://amzn.to/2qNwlMT

1x 10kΩ Potentiometer: http://amzn.to/2qNnpXy

1x LM393 Comparator: http://amzn.to/2ssBn2f

1x TLC555 Timer: http://amzn.to/2rGgUZX

1x 74HC04 Inverter: http://amzn.to/2qPW8YA

1x IR2113 MOSFET Driver: http://amzn.to/2rG7qxK

2x IRLZ44N MOSFET: http://amzn.to/2rFR3Bk

1x 7805 Voltage Regulator: http://amzn.to/2rGe1bL

1x 7812 Voltage Regulator: http://amzn.to/2qNx5S0

2x PCB Terminal: http://amzn.to/2qPZniW

3x 47µF, 1x 22µF Capacitor: http://amzn.to/2ssBJWD

7x 220nF Capacitor: http://amzn.to/2ssm3Tz

3x UF4007 Diode: http://amzn.to/2rFQd7S

2x 10kΩ, 2x 10Ω, 1x 2kΩ Resistor: http://amzn.to/2qPPnWG

2x 33µH Inductor: -

Amazon.de:

1x 3.5mm Audio Jack: http://amzn.to/2rpKbHN

1x 10kΩ Potentiometer: http://amzn.to/2rT8PSN

1x LM393 Comparator: http://amzn.to/2rG3dKL

1x TLC555 Timer: http://amzn.to/2qUBsd9

1x 74HC04 Inverter: http://amzn.to/2rGfizn

1x IR2113 MOSFET Driver: http://amzn.to/2rpQWtr

2x IRLZ44N MOSFET: http://amzn.to/2rT1X7R

1x 7805 Voltage Regulator: http://amzn.to/2ryYCI3

1x 7812 Voltage Regulator: http://amzn.to/2qUK5EG

2x PCB Terminal: http://amzn.to/2qQ1ymz

3x 47µF, 1x 22µF Capacitor: http://amzn.to/2qPYdE6

7x 220nF Capacitor: http://amzn.to/2rGg1k5

3x UF4007 Diode: http://amzn.to/2qUxLnM

2x 10kΩ, 2x 10Ω, 1x 2kΩ Resistor: http://amzn.to/2ryTxiV

2x 33µH Inductor: http://amzn.to/2rG8wtn

Step 3: Build the Circuit!

Here you can find the schematic of the project with and without the LM386 preamplifier. Feel free to use the pictures of my finished perfboard circuit as a reference.

You can also find the schematic on EasyEDA: https://easyeda.com/editor#id=74409197e62e4ff6b09d...

Step 4: Success!

You did it! You just built your own Class D Audio Amplifier!


Feel free to check out my YouTube channel for more awesome projects:

http://www.youtube.com/user/greatscottlab

You can also follow me on Facebook, Twitter and Google+ for news about upcoming projects and behind the scenes information:

https://twitter.com/GreatScottLab

https://www.facebook.com/greatscottlab

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    30 Discussions

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    AliA742

    Question 7 months ago

    can i use ir2110 instead of ir2112

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    FunVA_OpEd

    8 months ago

    It would be great if in addition to the app, you can add a Wi-Fi recover module to this project, preferably aa this date, using 802 11.AC or better, and build a full signal, separate transmitter project that can stream output from an AVR or other audio source to the receiver on the amplifier module. Best of both worlds just have the receiver be a separate module that you could add onto the amplifier with just a plug-in. Wi-Fi modules today are extremely cheap, but if you say that it needs processing and many other things, then you can just add an anadreno board or raspberry pi and modify it appropriately since at least the later already has much audio processing capabilities, Wi-Fi, ethernet, low power, very easily able to connect to other projects, programmable, and very very inexpensive. That doesn't even touch upon its other capabilities which would really make an amplifier such as this into a truly world-class product for pennies on the dollars compared to what is sold in the marketplace today, especially if all the questions, comments, and improvements that have been offered on the amplifier are implemented, where they make sense.
    Also not sure when you started this project but maybe there are better / alternative chips out nowadays? Lastly it was just certain types of components versus Stating the quality of the components that you offered as examples. Some may want to build a very high-quality amplifier using this as a guide, perhaps you can offer different classes of components that people could use from starting to professional. I think this is a great article I'm just offering suggestions where you could take it further.

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    FunVA_OpEd

    8 months ago

    I noticed that you do not have a tool section with their costs and which ones to order. That might be helpful for beginners. Also consider a low bit more advanced but easier ways of doing soldering such as using solder paste and cover how to correct bridges etc. You should at least cover the soldering paste application versus soldering each lead. You don't have to cover the details of how to do it but just the application to your project. There are many YouTube videos on how to do soldering for entire boards with many electronics, at once is using solder paste, which is especially nice for microcircuitry.

    Also, all these questions and comments need to be answered. If not somebody should then take the basis of this project, all the input from that, and take the next leap forward. A person wanting to create an app, or what many of these comments and questions addressed before they would create this particular project. I know such projects are evolutions, but if questions and comments go on answered on the original design unchanged, then people lose faith in that particular circuit.

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    attiny85

    8 months ago

    how did you set the dc offset on the output of the lm386??

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    johnyradio

    10 months ago

    Hi, awesome work. But, why does your sine wave sound like a sawtooth? Many audible harmonics.

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    narb08

    1 year ago

    Can you recommend a good alternative/equivalent to the IRLZ44N?

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    SamyakJ4

    1 year ago

    I made it but doesn't get any output at the end of circuit and what about the connection of audio jack (how we can identify the 3 pins out of 5...) please suggest .. any one help me

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    DmitriyU2

    1 year ago

    Great instructable and amazing video! Thank you!

    What is missing, from my point, is a test for max power output, and distortions analysis.

    1 reply
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    bassbindevilDmitriyU2

    Reply 1 year ago

    Also, signal to noise measurements, and frequency response. RMAA could do that using a computer sound card, except there is the problem of the bridged output. I'd try a sound card with optical input and a battery-powered ADC with optical output (eBay, analog digital audio converter).

    I suspect performance will be unimpressive, since there's no feedback. Suitable for a vehicle PA horn or siren, the kinds of music production applications where distortion is a good thing, or a science fair project. If you actually want to listen to music, there are awesome little class-D amp boards from China for the price of a burger combo.

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    Polymorph

    1 year ago

    All the unused inverters need to have their inputs grounded. Never leave inputs floating.

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    asfi235

    1 year ago

    Yeah, there's a DC offset on the output which will toast the speaker. The easiest way to get around this with single-supply operation is to use a full-bridge circuit. Yes, more parts, but you get better fidelity too. See:
    http://www.infineon.com/dgdl/an-1071.pdf?fileId=55...

    [International Rectifier AN-1071: Class D Audio Amplifier Basics]

    Adding the input buffer/preamp is an inherently good idea, though I don't see why you'd use a small power amp for the job. No harm in doing it this way, though.

    The 74HC04 would be even better if you used it to buffer both phases. Fast clean edges are best. And ground the unused inputs on the IC!

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    slimtender.

    1 year ago

    Very interesting circuit!

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    AgilePhil

    1 year ago

    I would have used the other half of your comparator as the inverter instead of adding another IC, but otherwise a great project.

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    CliveB10

    1 year ago

    Doesn't using a saw tooth wave instead of a triangle for the PWM make the amplifier non-linear, and create distortion? - I also agree with andyfras - you should decouple the speaker.

    1 reply
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    FindlayFCliveB10

    Reply 1 year ago

    Saw tooth or triangular does not matter. The slope of the ramp must be absolutely linear to give overall O/P linearity. This can be achieved b driving C5 with a switched constant current. Efficiency depends entirely on comp, buffer , mosfets switching as fast as possible.

    Use of a large electrolytic to the speaker will stop possible core saturation of the inductor and the speaker.