Communications and Media

Introduction and Objectives
Cellular phones, satellite television, walkie-talkies, car radios, GPS, and baby monitors all rely on radio waves (Brain, 2010). An understanding of how those equipments work entails an understanding of radio waves. One of the most effective ways to learn about how things work is by building them from scratch. As a point of departure, we propose the building a crystal radio, the simplest form of radio that requires no power source (eHow, 2010).

The objectives of this project are two-fold 1.) to build a crystal radio with the help of existing do-it-yourself articles. 2.) to experiment and make modifications for its further improvement.

A possible problem to be faced is with, in the experiment is that output audio signals will be of low amplitude. This means that the radio users may have difficulty hearing the radio broadcasts clearly.
Hypothesis

Incorporating an audio amplifier in the crystal radio may increase the amplitude of the output audio and thus improve audio quality.

Materials
Part A Basic Crystal Radio
The following are the basic materials essential for the project 1.) one 16 oz. sturdy plastic bottle which is five to seven inches long 2.) 50 ft. 22-18 gauge enamel-coated magnet wire 3.) one germanium diode which will serve as the crystal diode 4.) a telephone handset 5.) one set of alligator clipsjumpers 6.) 50-100 ft. stranded insulated wire which will serve as antenna (eHow, 2010).

Part B Modifying the Crystal Radio
Multimeter
Amplifier
The following materials may be of help in the creation of the project 1.) masking tape 2.) 6 in. by 9 in. wooden mounting board.

Procedure
Part A Basic Crystal Radio (eHOw, 2010)
Make two holes 0.5 inch apart near the top of the bottle. Similarly do two more in the bottom. The holes should only be slightly larger than the wire.

Pull approximately 8 inches of wire and insert and thread it through the bottom holes. Use the long end of the wire and wrap it around the bottle five times keeping each round close to previous one. Make a loop of wire around a pencil. Temporarily leave the pencil in place.

Make another loop of wire by winding another five times as done earlier. Keep wrapping the bottle with wire by making winding with five turns at a time making a loop around the pencil every five turns made around the bottle. This is done until the whole bottle is completely wrapped in wire down to the second set of holes at the bottom. Trim the end of the wire to 8 inches and thread it through the two bottom holes.

Once the bottle is completely wrapped in wire, the pencil can be removed. Strip the insulation from the tips of the enameled wire and from the small loops or taps made around the pencil. The insulation from vinyl-coated wire is to be removed.

The germanium diode should be soldered to the bottom of the wire. Use alligator jumpers, or twist the wires and tape them. Soldering however is the best option.

Cut the end off the telephone handset cord and then remove one of the modular connectors and find four wires inside. Solder the German diode to either the yellow or black wire. Solder the other wire which is yellow or black and solder it to the wire at the top of the bottle.

Find a ground and attach an antenna to the radio. The antenna can be an insulated wire that should be as high and long as possible. The ground can be made by connecting to a water pipe, or to a metal rod that is pounded at least 2 ft. into the ground.

Clip an alligator jumper to one of the taps on the coil and clip the other end of the antenna. Join a second alligator clip to the wire at the top of the bottle (the ground wire.) Listen to different radio stations on the telephone handset by clipping the alligator to the other taps on the coil.

Part B
Part of the experiment and the research is to determine where the amplifier is to be incorporated in the circuit. Once the amplifier is attached, multimeters may be used to measure changes in output amplitudes. A qualitative observation on the sound quality may also be made by the researcher.