e.g. If a phone charger is plugged into an outlet yet has no phone connected to be charged, why does it draw power?
In: Technology
They don’t anymore. If it says “switching power supply” it shuts off when not in use.
Older ones drew power because it has to drop 120v or 240v down to 5v, and convert ac to dc. The circuitry draws power whether it’s being used or not.
Newer ones have a capacitor, similar to a battery that once full, triggers the device to shut down. As soon as you plug in your phone it draws power from that capacitor, triggering the charger to start powering again.
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