When I first moved to Canada, I had no money. I lived in an apartment block with a coin-operated washer and drier. But I always had to go down the hall to check if my laundry was done.
So I had the idea to wind some wires around the power cable to detect the electromagnetic field changes when the machine turns on and off. Then this could send a message to a Raspberry Pi which could ping me somehow.
I didn't want to leave my Raspberry Pi hanging around in that semi-public area though. Also, I couldn't afford one at the time anyway!
But I want a bit to be flipped somewhere, so I can check at my leisure. If I miss the FM transmission I have to go down the hall to check again (Over the past ten years I've missed the last 100% of all FM transmissions passing through my local area)
If washing is not ready (currency is high) do nothing except of maybe accumulating energy.
Else send an endless beep on any frequency you like before you manage to take your laundry and disactivate your FM beeper.
It still can be implemented using a few transistors. Bonus points if implementation of this will be done in such a way that other folks can have a good use of the device.
That's smart. You could probably cram that into a official-looking nondescript plastic box with a backup battery that slots over the wire. Now you'd just need to keep the transmission power low
So I had the idea to wind some wires around the power cable to detect the electromagnetic field changes when the machine turns on and off. Then this could send a message to a Raspberry Pi which could ping me somehow.
I didn't want to leave my Raspberry Pi hanging around in that semi-public area though. Also, I couldn't afford one at the time anyway!