This instructable will guide you through the steps of using the PAM8403 CLASS D DC STEREO AMPLIFIER.
Step 1: BASICS
THIS TINY AMPLIFIER OPERATES ON 5V DC AND PRODUCES AN OUTPUT OF 6W ( 2 X 3 W ) .
This is one of the cheapest and most powerful stereo amplifier, provided with proper wiring and power sources.
The IC does not require a heat sink, so this will be perfect for your custom speaker project.
This amplifier costs about 80 cents in the U.S and around 50 Rupees in India.
The dimension of this board is 2cm x 2cm only !!!
DON'T SHORT THE GROUNDS OF THE LEFT AND RIGHT AUDIO OUTPUTS WITHOUT USING A . There will be a schematic below if you want to attain common ground for making headphone amps.
AVOID PROVIDING MORE THAN 6 Volts.
I WILL DEFINITELY NOT RECOMMEND YOU TO BUILD THIS ON A BREADBOARD, THE DISTORTION RATES ARE HORRIBLE !!!
USE CO-AXIAL CABLES FOR THE DC INPUT AND AUDIO INPUT. FAILING TO DO SO WILL RESULT IN HORRIBLE RF INTERFERENCE AND BAAAD AUDIO OUTPUT.
THE AMPLIFIER BOARD COMES IN TWO VERSIONS, ONE WITH VOLUME CONTROL AND ONE WITHOUT. There's a schematic below to add your own volume control.
Step 2: THE CONNECTION
The board basically has every connection labels imprinted so you don't need to go through rocket science for the connections.
Anyways, as i had mentioned earlier, use a shielded cable for the inputs. Normal wiring can be done for the outputs.
Find yourself a aux cable or any cable with a male stereo pin.
NOTE : SHORT THE GROUNDS OF THE AUDIO INPUT AND THE VOLTAGE IN
Step 3: FOR TRS PINS ( 3 Leads)
You will find three wires in basic aux cables, two of them are signal wires and one is the ground, usually the black or yellow wire is the ground.
IF YOU DON'T KNOW WHICH WIRE IS CONNECTED TO WHICH LEAD:
1) GET A MULTIMETER AND SWITCH IT TO CONTINUITY MODE
2) Connect one cable of the MM to the bottom lead of the pin and the other cable to any wire
3) IF you hear a beep then it means that those two terminals are connected to each other.
4) Do the same for the signal pins. Anyways you can interchange left and right signal inputs, it doesn't make any difference to the circuit.
SOLDER THE WIRES TO THEIR RESPECTIVE PADS.
Step 4: FOR TRRS PINS ( 4 Leads)
In this case, there will be four wires, two for signal, one for ground and one for +ve voltage in, this wires is basically for the inbuilt microphone of your earphones/headphones.
You will require only the SIGNAL AND GROUND PINS.
Step 5: THE USB CABLE
Ok so you will see four wires, +ve V, -Ve V, Data -ve and Data +ve .
You need only the +ve and -ve V wires.
Solder them to onto the respective pads on the board.
You will usually find aluminum shielding below the first plastic layer, strip that off, then you will find aluminum wires surrounding the four colored wires,, strip them off too.
Step 6: CONNECT YOUR SPEAKERS
This amplifier is capable of driving any speaker! In my test i had it connected to two 8 Inch subwoofers rated 8ohms 100Watts each. But yeah, it won't be spitting out it's peak output power and you won't be satisfied with it if you use huge speakers! ...
SO THE SPEAKERS TO GO WITH THIS AMPLIFIER IS :
Any FRS rated 4- 8 ohms 10 Watts
or any other speaker with an impedance of 4-8ohms and 10watts power...
BEST RESULTS CAN BE ATTAINED USING 4 Ohms 3 Watts speakers.
NOTE : DON'T SHORT THE GROUNDS OF THE SPEAKERS, THIS WILL DAMAGE THE IC. FOLLOW THE CIRCUIT BELOW TO ATTAIN COMMON GROUND
Step 7: VOLUME CONTROL
1) Get a 10 K ohms Audio taper stereo potentiometer ( in simple words, two potentiometers with single knob resulting in same output)
2) Connect the left output to the top left pin of the pot
3) Connect the negative of a 10 uf electrolytic cap to the top middle pin of the pot and connect the positive of the cap to the amplifier's left input.
4) Connect the top right pin of the pot to the amplifier's ground.
5) Connect the right output to the lower left pin of the pot
6) Connect the negative of a 10 uf electrolytic cap to the lower middle pin of the pot and connect the positive of the cap to the amplifier's right input.
7) Connect the lower right pin of the pot to the amplifier's ground
NOTE: IN THE SCHEMATIC, THERE ARE TWO POTENTIOMETERS , DON'T GET CONFUSED, IT's TO DEPICT THE STEREO POTENTIOMETER ( 2 in 1 Pot ) .
Step 8: COMMON GROUND
IF you are looking forward to make a headphone amplifier, you can't directly short the ground pins of the output, please follow the above circuit.
Step 9: TEST IT OUT
Connect the power supply
It's normal to hear slight humming from your speakers before connecting your audio cable.
Connect your audio cable, now the humming should have disappeared.
That's it!!! Play your track and comment below if you have any issues with the amplifier and i will try solving it :D
Thanks and stay tuned :D