Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space.
Information is carried by systematically changing (modulating) some property of the radiated waves, such as amplitude, frequency, phase, or pulse width.
When radio waves pass an electrical conductor (antenna), the oscillating fields induce an alternating current in the conductor. This can be detected and transformed into sound or other signals that carry information.
How to use a radio during a disaster
- Buy a radio that can run on batteries and either solar or dynamo cranking.
- Turn on your radio and listen for emergency information.
- If you have a weather radio, it will turn itself on and broadcast the emergency information.
- If you don't have a radio, you can make one by following the steps below.
How to make a crystal radio
If you appreciate ingenuity, simplicity, and like instant gratification from your radio projects, then you ought to spend a few minutes building your own foxhole radio. Foxhole radios were built by GIs in World War II from materials they had easy access to in the field. They usually consist of just a coil and a detector. They use a point detector, the chief component being an ordinary razor blade.
Steps
Note the simplicity of the design. Parts were assembled on a piece of wood, usually held in place with thumbtacks. The safety pin is anchored at one end and placed so the point may be moved around on the surface of the razor blade.
According to an article in Popular Mechanics of October, 1944, the blued steel surface of the blade gives the rectifying action needed for detection without crystals.
For better results add a pencil lead point.
To build a foxhole radio in a few minutes using the previous diagram, but with a pencil point. Fashion a safety pin shape out of stiff wire, then tie about an inch of pencil lead to it with finer wire. The radio will work the first time it is tried.
The antenna can be any wire covered or bare, as high and long as possible. Make sure you don't get around electrical wires for your safety and the performance of the radio. Also don't let the antenna "ground out" to trees or the earth (ground). You can make insulator from plastic water pipe or couplings.
The Emergency Alert System (EAS) is a national warning system in the United States put into place in 1997, superseding the Emergency Broadcast System (EBS) and the CONELRAD System. It is jointly coordinated by the Federal Communications Commission (FCC), Federal Emergency Management Agency (FEMA), and the National Weather Service (NWS). The official EAS is designed to enable the President of the United States to speak to the United States within 10 minutes (this official federal EAS has never been activated). The EAS regulations and standards are governed by the Public Safety and Homeland Security Bureau of the FCC. Each state and several territories have their own EAS plan.
A windup radio or clockwork radio is a radio that is powered by human muscle power rather than batteries or the electrical grid. In the most common arrangement, an internal electrical generator is run by a mainspring, which is wound by a hand crank on the case. Turning the crank winds the spring, and a full winding will allow several hours of operation. Alternatively, the generator can charge an internal battery.
Learn how to build simple radios - sci-toys.com
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