radio

HISTORY Towards the end of the 19th century scientists were attempting to send messages over distances without wires. They were not searching for a means of mass-communication, but simply exploring the possibility of using electromagnetic waves in order to communicate between two fixed points. There in no single inventor of radio, it came from several international developments. The pioneers of radio studied the work of a British physicist James Clerk Maxwell, who published his theory …

…by using an antenna, which intercepts part of the radio waves. A signal voltage across the coil induces a voltage in the coil, the frequency (AM, FM) is then chosen by the variable capacitor. The capacitor in my circuit is only tuned for AM. Then the frequency comes out of the capacitor and into the transistor, which you use to tune your radio to a station on that frequency. The average electrical power used is: