ZERO ENERGY WRITING POCKET RATTLE

by Willem van Dreumel

ZERO ENERGY WRITING POCKET RATTLENo batteries, no solar cells, just manpower! An electronics project for printing people, should be without the necessity to make a printed circuit board (not everybody has that capability). Only very simple and basic soldering is required. In spite of that, the project has a certain level of complexity. That’s why Arduino comes in. The Nano3V has a small footprint and is very low cost. A simple monochrome 10 led air writer, based on persistence of vision (POV) , is presented here. Easy to make, without skills in electronics We probably all played with a rattle as a child. Turning it around, making lots of noise. So we will make a rattle! Since a green project gives a better chance to win the Makerbot, we add a small geared DC motor to the rattle to generate the electricity for the Arduino . The energy is supplied by the user of this gadget himself . When blinking leds are moved through the air, we see dotted lines. With ten leds in a row, blinking in a synchronized way, we can write characters in the air. A small geared dc motor has to supply about 12 volts. The geared motor shown, or something similar, is exactly what we need. Buy it herehttp://www.aliexpress.com/snapshot/6604610388.html?orderId=66765675522572or use the specification to select one yourself.The SCAD file is included for eventual adaptions to the motor size.By rotating the 3D printed mid air led printer, the leds move in a circle, writing lines in the air.Arduino synchronizes the blinking of the individual leds. The color of the leds can be chosen as long as the right series resistor is used. For 20 mA green and blue leds, a resistor of 82 (or 100) Ohms is used. For red leds we need 150 Ohms. Make sure the leds are diffuse. A clear led throws the light in a bundle and is not visible outside the angle of the beam. A diffuse led is visible from all angles. The NanoV3 is plugged into a mini breadboard, widely available in electronic shops.Ten leds are mounted into the ho