This is a pretty simple project that will give you back-up power in the palms of your hands! Shared by Techgenie on Instructables:
We all know that when the electrical power is supplied to a motor, it rotates mechanically but when the shaft is rotated mechanically, the motor generates electrical power. So, in this Instructable, we will work on a small project that will utilise this above said principle on a geared DC motor to work as a electricity generator for making a hand powered 5v USB Charger for mobile phones. This device can also be used as a 5v DC power supply for various projects.
Make a robot friend with Adafruit’s CRICKIT – A Creative Robotics & Interactive Construction Kit. It’s an add-on to our popular Circuit Playground Express, FEATHER and other platforms to make and program robots with CircuitPython, MakeCode, and Arduino. Start controlling motors, servos, solenoids. You also get signal pins, capacitive touch sensors, a NeoPixel driver and amplified speaker output. It complements & extends your boards so you can still use all the goodies on the microcontroller, now you have a robotics playground as well.