Measuring Power Line Frequencies with Junk

Starting the weekend of Saturday, February 8th, the Baltic states’ (e.g. Estonia, Latvia, and Lithuania) electricity grid switched from being synchronized with Russia’s power system to the EU. While both systems run at 50 Hz, this process meant first disconnecting from the Russian grid, running without synchronization as an island system, then syncing up with the EU grid and throwing the proverbial – and perhaps literal – breaker.

Ideally, such a process would go without a hitch, transparent to the vast majority of people in the region. But what if you wanted to see what happens? And let’s just assume that you (wisely) don’t want to plug anything directly into your wall socket. As shown here, mononymous hacker halcy (AKA Lorenz) came up with a measurement solution that uses just the “junk you have in your closet.”

Halcy’s hack is rather ingenious in its simplicity. All he did was plug in an audio cable to a PC’s line-in jack, then wrapped it around a power cable a few times and listened for the resulting noise. He then processed this data in Python to pull out the (normally detrimental) 50 Hz hum for measurement. This was then overlaid with the frequency from f50hz.de that shows European frequency readings, resulting in a graph that shows when the switchover took place.

It’s a pretty clever hack, and a good reminder that you don’t always need fancy equipment to perform an interesting hack/experiment. It’s also really cool that halcy was able to observe a meaningful moment that would have been invisible if he wasn’t prepared and paying attention!