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.
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
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
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.