Boost converter from parts
Close the switch and the inductor stores energy from 5 V; open it and the inductor’s collapsing field adds its voltage on top of the input, pushing current through the diode into the output capacitor. The output rises to V_in ÷ (1 − D).

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How it works
Ideal: V_out = V_in ÷ (1 − D) = 5 ÷ (1 − 0.50) = 10.00 V.
Less the diode drop (0.38 V) and the coil’s resistance carrying 397 mA: 9.33 V.
Coil ripple V_in·D ÷ (L·f) = 500 mA p-p around 397 mA: continuous mode.
Try it on the bench
- Raise the duty to 60 %: about 12 V.
- Remove the load (variant): with nothing to take the energy, every cycle pumps the capacitor higher.
Parts on the bench
- 2 × Bench power supply
- PWM controller + gate driver
- Axial choke
- N-channel MOSFET
- Schottky diode
- Electrolytic capacitor
- Resistor
In the course
Electronics Engineering, module “Diodes and supplies”.