boost converter

A switching circuit that pushes voltage up, seemingly for free, like a child on a swing pumping a small motion into a big arc. The trick is the inductor: while the switch is on, current ramps up storing magnetic energy; when the switch opens, the inductor's collapsing field flings its stored energy on top of the input, kicking the output above V_in. A diode catches that surge into a capacitor.

This is how a 3.7 V lithium cell powers a 5 V USB port, how solar panels reach grid voltage, and how camera flashes charge to 300 V. The output is V_in / (1−D), so D = 0.5 doubles the voltage and D = 0.8 quintuples it. Energy is conserved: as voltage rises, the input draws proportionally more current, so a boost can't conjure power from nothing.