There is no need for any device. A simple circuit in you charger tells it if something is requesting resources so if nothing is connected no resources are consumed.
Think of a light bulb that will last forever and use no electricity if you don't throw the switch. The lightbulb knows to light up if something like the light switch makes a connection to the power which resides in the outlet.
There is no need for any device. A simple circuit in you charger tells it if something is requesting resources so if nothing is connected no resources are consumed.
Think of a light bulb that will last forever and use no electricity if you don't throw the switch. The lightbulb knows to light up if something like the light switch makes a connection to the power which resides in the outlet.