How many times have you been without a battery? I often! I then decided to hack the nice coffee grinder shaped IKEA Ljusa hand powered flashlight.
The procedure was simple it was enough to eliminate some resistors and use a capacitor sufficient to handle the charge given by the Ljusa’s dynamo.
I set the output voltage to 5 volts, and I installed a USB socket. It only remained to modify the body of the torch. Then I printed the bottom of Lyusa filament transparent leaving only the space for the female USB plug.