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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

 Component Type
 Reference
 Description Quantity Possible sources and notes
 Printed Circuit Board
  Gerber and KiCad files provided below
 1 Order at OSH Park or make it yourself. See attachments for Gerber files.
 Integrated Circuit
 U1 ST TDA2003A
 1 Mouser 511-TDA2003AV
 Capacitor C1 Ceramic Capacitor, 8.2 nF
 1 Mouser 810-FK28C0G1H822J
 Capacitor C2, C3
 Ceramic Capacitor, 0.1 uF
 2 Mouser 810-FK28X7R1H104K
 Capacitor C4 Electrolytic Capacitor, 10 uF, 50V
 1 Mouser 647-UKT1V100MDD
 Capacitor C5 Electrolytic Capacitor, 470 uF, 50V
 1 Mouser 647-UKW1V471MPD
 Capacitor C6, C7
 Electrolytic Capacitor, 1000 uF, 50V
 2 Mouser 647-UKW1V102MHD
 Resistor R1 Metal film, 1 ohm
 1 Mouser 660-MF1/4DCT52R1R00F
 Resistor R2 Metal film, 4.7 ohm
 1 Mouser 660-MF1/4DCT52R4R70F
 Resistor R3 Metal film, 100 ohm
 1 Mouser 660-MF1/4DCT52R1000F
 Resistor
 R4 Metal film, 470 ohm
 1 Mouser 660-MF1/4DCT52R4700F
 Resistor  Metal film, 1 kohm
 2 Mouser 660-MF1/4DCT52A1001F
 Connector P1 Pin Header 2x1, 2.54 mm lead spacing
 1 Mouser 649-68002-102HLF
 Connector
 P2, P3
 Screw terminal 2x1, 5.00 mm lead spacing
 2 Mouser 651-1935161
 Connector P1 Pin Header female connector
 1
 Mouser 855-M20-1060200
 Mouser 855-M20-1180042
 (Note: this is a 100 pieces bag of contacts, only 2 are needed for this project)
 Connector  3.5 mm stereo audio jack
 1 RadioShack 274-249
 Connector  5.5 mm x 2.1 mm DC jack
 1 RadioShack 274-1563
 Potentiometer  10 kohm audio taper, with switch
 1 RadioShack 271-215
 Knob  Knob for the potentiometer
 1 RadioShack 274-424
 Speaker  8 ohm speaker
 1 We used two speakers: one low-mid range and one high frequency (tweeter) connected through a crossover capacitor.
 Wires  Color wires to connect the board to external connectors, potentiometer, and speakers
 1 m
 Use color wires: e.g. black for ground, red for power, different colors for audio in and audio out lines.
 RadioShack 278-1224
 Power supply
  12V / 1A DC brick-type power supply
 1 Amplifier IC needs supply voltage to be in 8V to 18V range.
 Speaker box
  MDF, wood, screws, etc.
  Home Depot 1/4" x 2' x 4' MDF


Ċ
Michael Kiselev,
Dec 3, 2013, 4:11 PM
Ċ
Michael Kiselev,
Dec 3, 2013, 4:11 PM
ċ
TDA2003 - KiCAD.zip
(15k)
Michael Kiselev,
Dec 3, 2013, 4:11 PM
ċ
TDA2003 - gerber.zip
(24k)
Michael Kiselev,
Dec 3, 2013, 4:11 PM
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