"I will definitely finish this over the next months" heh.. no.. I lied.
But I got back to it and completely revamped the hardware and just finished a new prototype.
The results I get with this new prototype are a LOT more promosing than what I got so far.
Instead of the old ATtiny setup I used just an ESP8266 and a MCP8421 18bit ADC. I found that I don't need the 18bits but given that the ADC is fairly accurate I can get a pretty clean reading at 12 bit and 8x amplification (using the built-in amplification).
This is how the new prototype looks like:
And this is a sample reading. Having a differential reading makes a huge difference. I didn't think about it before but with AC current it doesn't really makes sense to do anything but a differential reading because otherwise you get nothing at all half of the time.
Now I will run some extended tests and if all goes well I will incorporate the new sensor board into my old software and write an algorithm for my machine. With the values I get this should be fairly easy. I found that every washing machine behaves completely different so you will always have to write a new algorithm for a new machine or implement some sort of end-user assisted machine learning algorithm.
I also made a schematic of the new board if anyone is interested. Maybe I make a PCB later on when I finished testing.
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