Portable Stereo Class-D Audio Power Amplifier




I did my Masters and Bachelors in computer science. I have been tinkering with Computers & Electr...

This Instructable is to build Portable Stereo Class-D Audio Power Amplifier using Texas Instruments Chip TPA3123D2. You can use this method to Assemble any ready made Amplifier into an enclosure too. This chip uses minimal components and is a great budget friendly amplifier for various applications. The Output of the Amplifier depends on the Voltage supplied between 10V and 30V. It can deliver 25-W/ch into a 4- Ω Load from a 27-V Supply and 20-W/ch into a 4- Ω Load from a 24-V Supply. For more details about TA3123D2, please refer to datasheet at http://www.ti.com/lit/ds/symlink/tpa3123d2.pdf.

Why Make your own? You can customize your circuit as needed for your application. It helps in learning and selecting quality components. The cheap amplifier boards tend to compromise on the quality of components used and may not be customized as custom builds.

Materials Required:
1. 1 x TA3123 Amplifier Printed Circuit Board (1)

2. 1 x TA3123D2 Texas Instruments Amplifier SMD Chip

3. 2 x 470uF 35V (Output Caps)

4. 1 x 1000uF 35V to 2200uF 35V (Power Cap)

5. 2 x 0.68uF 63V Polyester Caps (EPCOS/WIMA or Panasonic)

6. 5 x 1uF 63V Polyester Caps (EPCOS/WIMA or Panasonic) —I am using MKS Capacitor type, MKP will be too big for this Circuit Board.

7. 2 x 0.22uF 63V Polyester Caps (EPCOS/WIMA or Panasonic)

8. 2 x 0.68uF 63V Polyester Caps (EPCOS/WIMA or Panasonic)

9. 2 x 22uH Inductors (Wurth or TDK)

10. 1 x DC Power Switch

11. 1 x 24V - 2 Amps Power Adapter

12. Connecting Wires

13. 1 x Aluminum enclosure

14. 2 x Speaker Output jacks

15. 2 x RCA Line-In jacks

16. 1 x D.C Jack for Power

17. 1 x 10K Log Potentiometer

18. 1 x Blue LED

19. 1 x 1K Resistor for LED

20. 2 Core Audio Shielded cable

Tools Required

1. Soldering Iron

2. Wire cutter/strippers

3. Helping hands

4. Drilling machine

5. Step Drill bit/Drill bits

6. Blue tape

7. Screw Driver 8. Nose Plier

Parts Source

Capacitors, TA3123D2, and Inductors were bought from Mouser Electronics in USA.

Capacitors: I recommend Electrolytic capacitors from Nichicon, Panasonic and Elna I recommend polyester and polypropylene type capacitors from Wima, Epcos, Vishay and Panasonic.

Input Cable: 2-Core Copper shielded cable This copper shielded cable reduces interference and improves audio signal quality https://www.ebay.com/itm/UL-2547-2-3-4-Core-Coppe...

Stereo Volume Control: Using ALPS Stereo 10K Log Potentiometer

Pin1: Ground (Short 2 Pins and Connect to GND)

Pin2: Connect to Line-In of Amplifier (Left/Right)

Pin3: External Input from RCA Jacks (Left/Right)

Step 1: Print Your Circuit Board

I used https://www.oshpark.com for ordering my PCBs. Attached is the PCB *.brd file which should be sufficient for ordering at Oshpark. 3 boards will cost you approx $17.50. They turned out good. I don't recommend printing them at home as they use 2 layers and missing any of the connections can fail the circuit. Shown here are 2 Layers of the PCB (Red - Top layer, Blue - Bottom layer) with Schematic.

Step 2: Start Assembly of Amplifier

Start from Small to Big. First solder the Amplifier Chip followed by small capacitors and increase in size etc.

The PCB has Polarity signs and values for Inductors and Capacitors. If you are not sure. Zoom on the Assembled amplifier circuit board and get the details.

Step 3: Prepare the Amplifier Enclosure

Mark and Prepare the Enclosure front and back side. The Back side need total of 8 holes drilled with different sizes. 4 holes for Speaker output jacks. 2 holes for RCA Input Jacks, 1 hole for Power switch and 1 hole for D.C power jack. Add rubber feet to the bottom of the enclosure.

Step 4: Strip the Wires for Connections

Strip the wires using the wire stripper and add little flux and solder to the wires so they connect well.

Step 5: Connect Wires to Input and Output Jacks

Connect wires to speaker terminals and Line in. The Line In uses a copper shielded cable. The Line In from RCA Jacks go directly to Volume Control and Center tap of the volume control goes to the Line In of the Amplifier.

Step 6: Final Check

Check all Wires connecting to and from the Amplifier. Check the Polarity of the Power (shown separately here).

Step 7: Close the Front Panel.

Test and close the front panel of the Amplifier and Enjoy your New creation.



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    4 Discussions


    2 months ago

    Where did you buy enclosure? I really like how you made things, however you should put heatsink on chip, even small one. You have a lot of room in your enclosure so it shouldn't be the problem.

    1 reply

    Reply 2 months ago

    I bought the enclosure on eBay. Yes, I can add a small heat sink, But I did not see the Chip getting any Warm for 14 Volts. Texas Instruments data sheet mentions in the 4th Bullet item on Page 1 that "Efficient Class-D Operation eliminates Need for ... Heat Sinks" But does not hurt to add it.