Week 19 - Final Project

The Final Outcome

I wasn't able to complete the full 16 channel full spectrum audio analyzer, however I was able to get a working prototype of a 2 bar LR channel. This smaller version basically works as a proof of concept, and I think the larger scale version was a little ambitious for only using the labs tools.

One of the original R&D testing prototypes. Used to fine tune the LM3915 circuit, and yes I love Sparkfun!


Testing out some reflowing in our toaster oven. Saves a lot of time, but you still need to be meticulous in your placement of components. The reflow does have some self-aligning ability but if the board is milled too deeply it wont always work.

Given the FR1 type circuit board material I needed to keep a close eye on the process.

2x20 Led array

Cutout File

Traces File

The amplification circuit. A simple LM386 audio amp, with board mount pot and headers for the 3.5mm headphone breakout board.

Eagle Board File

Eagle Schematic

The bar driving circuit. Cascaded LM3915's. The wording is intentionally mirrored on the bottom layer so that it can be milled correctly on the modela.

Eagle Board File

Eagle Schematic

Testing led alignment. By using 2 columns on the circuit board you can access each side to use tweezers to align the led into the cutout.

In the days leading up to the final presentations I came extremely close to finishing the massive soldering job. I did come to the realization that I wouldn't finish, so I decided to make a quality "working" prototype rather than show off an ambitious non-working unit.

Final Project Photos