This ain't no Sangamo. Home made energy kWh meter.

[Kurtreidable]

The big spike is the inrush. A bench grinder has a big inrush.

[narcoti]

By the way how do you filter out the noise on your soundcard, or is there none? What soundcard do you have?

[ChumpusRex]

@narcoti There's not much noise on the soundcard. There is a bit on the 'current' channel, as the signal I'm measuring is so tiny. I've got a 100 A current transformer which I'm using to measure 0.25 A, and I've just shorted the CT out with a short piece of wire, which has very small resistance, so I get a very small voltage.

I use a creative X-fi card. I actually got better results with my integrated sound, but I think I broke the analog input with a bad connection, so I use the crappy x-fi.

[narcoti]

The harmonics look much much nicer now, I feel safer plugging my computers into the wall now. :) You should consider making a kit, or pre-made solution, and sell it. I see your software, and designs outselling the kill-a-watt meter, due to the fact that you can use it as a DSO, over network and on a pc. Your work is amazing!