Radio Parts

                              Learn about how a radio works








Here is a labeled picture of a radio circuit. Click on it to see a bigger preview.
       - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
To make a radio work you need all the parts of a radio. To build a radio you need to know how the parts work.

In my class, we have built a working radio. We are now studying the parts of a radio. Each of us has to make a report on a part of the radio that we were assigned to do. Each part has two people searching about it. My friend Michelle and me are assigend on the part called a variable capacitor.

Here is the report that I did about it.

Variable Capacitor

            A variable capacitor is one of the components that you need for making a radio. It is a compound machine because it is built up of more than one simple machine. 

            It is used for setting the frequency of things like radios. Variable capacitors are also used in a way to tune a radio, that is why they are sometimes called tuning capacitors. 

There are different types of variable capacitors. For each type of capacitor, some of the components are different from other types. The two basic components of a variable capacitor is the two electrodes, which consist on rotors(the moving part), and starters(fixed in place).

            Variable capacitors work by moving the rotor to find the right capacitance, to get the resonance frequency. It works by letting the high frequency pass, while the inductor(antenna coil) lets the low frequency pass. These two frequencies will meet in one point, in this point it is as if the frequencies mix up, and then let a tuned frequency pass to the speaker.

            The more plates a variable capacitor has, the higher the capacitance. The less plates a capacitor has, the lower the capacitance. The further apart the starter and rotor, the smaller the capacitance(which will make a lower frequency). The closer the starter and rotor, the bigger the capacitance(which makes a higher frequency).



Conversation with Herman in Indonesia first of December 2007, from 7:00pm-9:15pm.