I’ve been considering how to put monitors on appliances… specifically, a stove (for left on alert) and washer/dryer (for finished alert). I’ve seen some solutions for washer/dryers based on vibrations, but that seems to be begging for false alarms. I’ve also seen solutions using power monitoring which isn’t out of the question, but at least with 220v are excessive in cost (and raises safety concerns). Another option is to use a light monitor on a LED indicator, but that not only seems like it wouldn’t be reliable, but would also be unsightly and cover the LED. Assuming I’m willing to void the warranty, would it be possible to connect a simple circuit on/off device like a water sensor to the leads of LED indicators in the device/appliance itself, allowing the sensor to be inside the device, while maintaining reliability?
TL;DNR: In short, could a water sensor be used as a LED on/off monitor? Is this a bright or dim idea (pun intended)?