3D printed hand crank/gravity generator

Are you in need for green, off grid electric energy ? I have a solution for you.
Small (almost pocket size) DIY 3D printed generator.
It can be used as hand crank generator OR you can change crank with spool attachment and use it as gravity generator.

This generator utilize small nema 17 stepper motor and planetary gearbox with ratio 25:1 that is mounted directly on nema 17 motor.
Thanks to this ratio we are able to do around 1500rpm.

Thanks to that RPM stepper motor can produce around 25-30V and about 700mA with no load.

I'm using two small bridge rectifiers up to 2A in paralel to get more current.

Then I connected output from those rectifiers into a variable step-down DC to DC converter with small voltmeter and USB female port.

This is just PoC / prototype for now, but it's usable and I'm planing to make it more mobile and with more tested attachments, outputs and many more changes that I discover along the RnD.

For planetary gearbox used here, please go see Ondrej's Nema 17 25:1 planetary gearbox, with instructions and list of parts.

Parts that I use:

• 1 x Small Digital Voltmeter 0.28 Inch 4-100V
• 1 x Nema 17 Stepper Motor
• 2 x W08M Bridge rectifier
• 1 x DC to DC step-down variable converter (in 4-30V, out 3-27V) … unknown origin with DIP switcher
• 1 x USB-A female port (or whatever)

Note:

18.4.2022 - This is still a work in progress (an over a weekend project). I am gonna make a few adjustments and few more gadgets that will use this generator to the maximum.

This project was inspired with work of:
RobertMurraySmith
Hand crank generator from - HyperSpacePirate
Nema 17 25:1 planetary gearbox from Ondrej (Thank you for awesome design)