Amplified Speaker

Introduction

One day Mike and I went to the local RadioShack and Mike got excited about an amplified speaker for an iPod which looked like a guitar amplifier. I suggested building similar one ourselves.

Project Documentation

Pictures

Click here for the picture gallery.

Schematic and PCB Layout

See attached files at the bottom of this page.

Construction

The amplifier is based on ST TDA2003 integrated circuit - a 10W car audio amplifier. The circuit we used pretty much follows the application circuit in the TDA2003 datasheet. Mike and I drew the schematic and designed the PCB using KiCad suite and ordered PCBs at OSH Park ($14.25 for a set of 3 boards). Most of components are mounted on the PCB, excluding volume control potentiometer, audio and power jacks, and speakers. We mounted the PCB on an aluminum plate (the plate initially came with RadioShack project enclosure) using IC thermal pad and a single 3 mm screw. So that the aluminum plate also works as a heatsink. We put some thermal compound between IC and the plate. Audio and power jacks, and the volume potentiometer are mounted on the same plate as well.

We reused drivers (speakers) from an old non-powered computer speaker, that Mike got for free at the local surplus store (they give kids a bucket and there are a few shelves that kids can dig for free stuff). The speaker box is built from 1/4" (6 mm) MDF, 4 wooden planks and some wood screws. We glued it with wood glue, and sealed the seams using a hot glue.

The speaker has a stereo input, so that a device with stereo output (like an iPod) can be connected to it. The stereo signal is converted to mono signals using a couple of 1 kohm resistors soldered on the audio jack. One lead of each resistor is connected to the input on the audio jack (one resistor to the left channel, another one to the right channel). Two other leads of both resistors are connected together and then connected to the volume control potentiometer.

Bill of Materials