Gadgets & Electronics
Inside a Phone Charger
From wall socket to USB in a box the size of a matchbox: the parts that make it safe.
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Gadgets & Electronics
How a Phone Charger Shrinks Wall Power
A phone charger turns mains AC into high-voltage DC, then switches it on and off tens of thousands of times a second through a small transformer. The transformer lowers the voltage and keeps you isolated from the mains, and the output is smoothed into steady low-voltage DC. With USB Power Delivery, the charger and phone agree on a voltage before more power flows.
Transcript
The wall gives 230 volts. Your phone wants 5. What's in the box? Let's cut it open. The power is chopped into a buzz, tens of thousands of times a second. A tiny transformer passes it across a gap. No wire crosses. The far side talks back with light. So the 230 never reaches your phone. Just 5.
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