RF help

[andrew8485]

Hello I am in the new in electrontics but I am eager to learn and have learned the very basics, such as caps, resistors, relays, ect. with the help of this board and online tutorals. but now I want to learn more and I was thinking about trying to learn about radio frequency that is used with remotes as well as fm radios and tried to do a search for some tororials by using the key words " fm tutorial" and "parts of a fm radio" but had no luck. do you guys have any sugestions for a site to go to or keyword to use to search.

 

[Roff]

I'm baffled as to why you didn't search for "rf tutorial". **broken link removed** is one hit I got as a result of that search. There are probably others.

 

[andrew8485]

thanks I just saved that site and will look at it later.

 

[andrew8485]

ok, i read a few sites now and understand how to make a radio receiver and transmitter, which i am glad of . But now i want to know how the cap and coil and other stuff sort out that one frequency and block all the other 8) . THANKS A MILLION for the reply

 

[Nigel Goodwin]

ok, i read a few sites now and understand how to make a radio receiver and transmitter, which i am glad of . But now i want to know how the cap and coil and other stuff sort out that one frequency and block all the other 8) . THANKS A MILLION for the reply

A capacitor and coil form a 'tuned circuit' which resonates at a certain frequency - imagine tapping a glass with a spoon, it resonates at a particular frequency, and only at that frequency. A capacitor and coil do the same thing, but electronically, not mechanically - and where you can alter the frequency of the glass by adding water to it, you can alter the frequency of the coil/cpacitor by altering either the coil or the capacitor.

 

[stevez]

Several amateur radio references are likely to be good sources of information. My favorite is the Radio Amateur's Handbook published by the American Radio Relay League. Since RF is a big part of the hobby you can exepct much of the book to focus on that subject. I know of no way to access it on-line.

 

[andrew8485]

Ok I like how you used a glass of water and a spoon. Hear is what I am understanding = the spoon acts like an Antenna of a transmitter and send a magnetic field into the air (or a wave in the water for the case of the spoon and cup). But now lets say there is another spoon (another radio transmitter on a different frequency) that hits the same cup of water (air) even though there on a different frequency it still affects the waves from the other transmitter. Causing a totally different wave that was transmitted from either one. this part Is confusing me. thanks once again and have a good holiday

 

[Nigel Goodwin]

Ok I like how you used a glass of water and a spoon. Hear is what I am understanding = the spoon acts like an Antenna of a transmitter and send a magnetic field into the air (or a wave in the water for the case of the spoon and cup). But now lets say there is another spoon (another radio transmitter on a different frequency) that hits the same cup of water (air) even though there on a different frequency it still affects the waves from the other transmitter. Causing a totally different wave that was transmitted from either one. this part Is confusing me. thanks once again and have a good holiday

You're going beyond the spoon/glass idea :lol:

If you want to carry it further, you've probably heard the stories about opera singers breaking glasses - no contact required, just singing a pure note at the glasses resonant frequency. If they sing at the wrong frequency nothing happens, but at the exact correct frequency the glass will resonate - breaking though, is a debatable matter. In a similar way a tuned circuit only responds to one frequency.