Altoids
Headphone Amp.

Start with a compact audio circuit

Audio Arduino Club offered a practical way to connect circuit theory with a physical build. The Altoids design uses two non-inverting amplifier channels to boost a wired headphone signal.

Build the club’s headphone amplifier

My task was to assemble the provided circuit and work through its compact packaging under Dr. Gary Tuttle’s guidance. The focus was component identification, soldering, and understanding the signal and power paths.

Work from the small parts outward

The build progresses from the input and feedback components to the socket, power switch, capacitors, and audio jacks. Two 9 V batteries supply the TL082 circuit. The enclosure design places the connectors through the tin and insulates the board from its metal base.

Circuit design and component choices

A TL082 dual op-amp provides one non-inverting stage for each stereo channel. The 15 kΩ and 1 kΩ feedback resistors set a nominal voltage gain of 1 + 15/1 = 16. The two batteries create positive and negative supply rails around a common ground, allowing the audio signal to swing on either side of zero.

Build process

1. Populate the small components

   Start with the input and feedback resistors, then the small capacitors. The board’s ground plane draws heat away from solder joints, making consistent heating especially important at ground connections.

2. Assemble and check the power path

   Add the socket, switch, battery terminal, bypass capacitors, and jacks. The guide calls for checking the supply rails and switch operation before installing the semiconductors; capacitor polarity and op-amp orientation are key checks.

3. Fit the enclosure

   The guide places two ¼-inch connector holes 24 mm apart in the tin. An insulating layer keeps the PCB underside away from the metal enclosure, while the connector nuts secure the board. The batteries share the remaining space.

The gain above is calculated from the design values. It is not a measured result from my individual build.

Connect electronics with packaging

I completed the Altoids amplifier project as a hands-on club build. It brought together stereo op-amp circuitry, through-hole assembly, and the mechanical constraints of a small enclosure.