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/sci/ - Science & Math

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4854054 No.4854054[DELETED]  [Reply] [Original]

Anyone have a good link on how VERY basic radio works? I remember having something that was explaining magnets, and how it's electromagnetic waves (which generate current and thus allow a measurable binary output), but I lost it.

Please halp.

>> No.4854064

Like, communications radio, or radio waves?

>> No.4854067

To elaborate, I want instructions on something very basic - anything that can send a pulse when circuit is closed and receive that pulse from, say, 2 cm, and have some sort of current output for a fraction of a second.

>> No.4854072

>>4854064

I am not sure what kind of distinction you are making. Basically, I want a way to send a signal through space, rather than wire. So, think telegraph without wire.

I don't want anything that will encode a song / voice /etc, send it, and then interpret it.

>> No.4854081

I'm not sure what part of a radio you want explained.

Radios exploit resonant frequencies in electromagnetic waves. It's the same thing as the famous bridge-being-destroyed-by-a-cat story, at a particular frequency the feedback loops in on itself and creates a massive surge in amplitude. When you tune a radio you're physically changing the distance between two capacitor plates, which changes the conditions under which you experience runaway resonance- namely, the frequency that has the resonance. This way, only the resonant frequency comes in, and that's what lets you tune to specific radio stations.

That's the rough idea, it's been a while since I did classical mechanics. Make sense?

>> No.4854088

>>4854081

That all makes sense. You are going too high level though.

Think about this. I want an antenna and a receiver dish across the street. When the antenna picks up anything from me, it lights a light bulb. That's it. That's all. I want to know how to build the antenna/receiver.

I don't care about voltage either, light bulb is hypothetical.

>> No.4854090

Drop a stone in the water of a still pond, and waves ripple out from the source of the splash. A radio transmitter makes a similar splash. A receiver interprets those waves.

>> No.4854098

>>4854090

Oh, no shit? A transmitter makes waves and a receiver picks them up? Oh, wow! It's, like, the definition!

I don't mean to be an ass, but come on man.

>> No.4854100

>>4854088
http://en.wikipedia.org/wiki/Spark-gap_transmitter

Is how the early ones did it. Do you want a practical one you can build at home or just a rough idea of how the early ones worked?

>> No.4854101

>>4854098

It's an analogous description, you ungrateful little cunt.

>> No.4854105

>>4854100

I wanted a very rough idea of how the early ones work. Thank you.

>>4854101

There is nothing to be grateful for - you didn't help. Everyone who passed 9th grade understands the concept of a wave. Applying it is an altogether different story though.