There’s a lot you can tell by looking at the waveform of your mains power. There are harmonics, transient changes, and periodic fluctuations that are correlated to the demand on the grid itself. Frequency shifts will tell you how fast or slow your clocks are running, and someone probably has a poorly isolated power line communication thing somewhere in your neighborhood. There’s a lot you can learn by looking at the waveform coming out of your outlets, but how do you tap into that? [David] is doing it with a PC sound card and some really interesting hardware.
The Grid 2 Audio module is [David]’s entry to this year’s Hackaday Prize, and it consists of three main parts. The first is the mechanical part of the design. This comes in the form of an IEC power socket with a built-in switch, fuse, and illumination. Of course, you could simply buy one of these, but [David] is teaching himself Autodesk Inventor, and you have to start somewhere. The second part of this build is the PCB power supply and mains input. This is basically a pair of transformers, a PCB, and a whole lot of isolation to make this a safe board. The third part is a signal conditioning board that sends the waveform to a 3.5mm jack, for easy processing with any audio capture hardware.
The hardest part of this board is, by far, the PCB design, and for that [David] went all out. There are some big, meaty traces on this thing and real separation between the high voltage and low voltage portions of the board. The end result is something that sends the mains waveform to an audio card for easy processing with MATLAB, and all the goodies that come from that.