Audio Amplifier
www.kitronik.co.uk
Build Instructions (continued)
The final connection is the audio input. Strip the insulation off the other end of the remaining cable
that has the jack plug on. Run some solder in to the wire and trim the wire so only 2 or 3 mm of bare
wire is left. Solder these wires into the board where it is labeled ‘input’. It doesn’t matter which of the
pair of wires goes each of the two pads.
Step 6
The IC can now be put into the holder ensuring the notch on the chip lines up with the notch on the
holder. Your amplifier is ready for use. You can use the volume control on your MP3 player to control
how loud the amplifier is. Just make sure it’s mid volume when you test the amplifier.
Adding an on / off switch
If you wish to add a power switch, don’t solder both ends of the battery clip directly into the board,
instead:
Solder one end of the battery clip to the PCB, either black to ‘-’ or red to ‘+’.
Solder the other end of the battery clip to the on / off switch.
Using a piece of wire, solder the remaining terminal on the on / off switch to the remaining power
connection on the PCB.
Checking Your Amplifier PCB
Carefully check the following before you insert the batteries:
Audio equipment may become damaged if connected to an incorrectly built amplifier.
Check the bottom of the board to ensure that:
All holes (except the 4 large (3 mm) holes in the corners) are filled with the lead of a component.
All these leads are soldered.
Pins next to each other are not soldered together.
Check the top of the board to ensure that:
The three wires are connected to the right place.
The ‘-’ on the capacitors match the same marks on the PCB.
The colour bands on R1 are brown, black, orange & R2 are brown, black, brown.
The battery clip red and black wires match the red & black text on the PCB.
The notch on the IC is next to the power connection.
