When the AC is on it will draw current through its power cord. It seems to me a simple induction system would be able to detect this current flow. Such a device is for sale right here on SparkFun.
https://www.sparkfun.com/products/11005
R
When the AC is on it will draw current through its power cord. It seems to me a simple induction system would be able to detect this current flow. Such a device is for sale right here on SparkFun.
https://www.sparkfun.com/products/11005
R