18-year-old Kelvin Doe is from Freetown in the Republic of Sierra Leone in West Africa. 

Kelvin grew up in a neighborhood that barely had any electricity, but he noticed that nearly everyone in his community had a radio. This inspired Kelvin's own fascination with electronics, but as the youngest of five children, his family couldn't afford to buy him any electronic gadgets of his own.  So when Kelvin was just 10 years old, he began picking through dump sites after school to collect pieces and parts of discarded electronics, because he knew in his heart that if everyone in his community had a radio, he could unite them and inspire them by making something they all could enjoy.

He built his own mixer, his own receiver, his own amplifier, and his own microphone. And then, to power it all, he took apart an old alkaline battery to find out what made it work. Once he had taught himself the basics of a battery after a lot of trial and error, he was able to make his own battery out of soda, acid, metal, and tape.  And then he found a rotting old voltage stabilizer that he turned into a generator. Once he had all of the other pieces in places, he climbed up on his roof with a makeshift antenna and began broadcasting his radio show of music and news under the name of DJ Focus. Why DJ Focus? Kelvin said, "They call me DJ Focus because I believe if you focus, you can do an invention perfectly."

He did it so perfectly, in fact, that he almost got himself shut down. Kelvin was funding his station by hiring other children as guest DJs. They would sell ads for the equivalent of $1.25. Kelvin would let the kids keep 50 cents and then invest the other 75 cents back into the radio station. Soon his signal was so strong that it began interfering with a major regional radio program, but he was allowed to stay on the air by agreeing to change his frequency. 

In 2012, Kelvin earned an opportunity to travel to the United States for the World Maker Faire in New York City, where he officially became the youngest ever Visiting Practitioner at the Massachusetts Institute of Technology -- a 16-year-old boy from a dirt-poor neighborhood in Africa who was presenting inventions he made out of garbage to college students who were older and more fortunate than he was. After his stint at MIT, he also lectured to undergraduate engineering students at Harvard.

You can watch Kelvin's Ted X talk on YouTube.