This is a widget which senses the current of your washer and dryer to let you know when they're done running.
This is different from similar projects in that it is reliable and doesn't require modifying your appliances. Typically, to measure current of an appliance, you'd need to split the cord so that you could attach a split-core current sensor. This is impractical and possibly dangerous. Instead, this project uses Hall-effect based current sensors.
This project supports notifying multiple people. It uses a button and an LED per person to toggle notifications.
Buttons and LEDs (note: LED current-limiting resistors are inline):
Cable gland for USB cable/sensor leads: