how ignorant are you?

[Catwoman]

glatt I have now read your post twice.

the answer to the first question is 'yes', but it never worked.

what I don't get is how movement translates into sound? is sound a movement? are sound waves tangible?

how do sqiggly lines on vinyl make the receiver play an EXACT replica? they'd have to be incredibly precise.

Originally Posted by glatt

Tapes have the electic signal saved to them in a magnetic dust that is applied to the tape

How?? How is the signal saved in magnetic dust? Do you just get a pile of crushed magnets and sing into them?

all this being said you are closest in line for being stood on in the near future

[Happy Monkey]

Originally Posted by Catwoman

what I don't get is how movement translates into sound? is sound a movement? are sound waves tangible?

Yes, and yes. You hear sound when the tight skin across your eardrum vibrates in response to the movement (vibrations) of air entering your ear.

how do sqiggly lines on vinyl make the receiver play an EXACT replica? they'd have to be incredibly precise.

They are analog, rather than digital, so they are like "tracing" a sound. When a record is recorded, the sound entering the recorder causes the blade to vibrate in a certain pattern on the prototype disc. When the disc is played, the needle traces that pattern and vibrates the speaker in the same way the original microphone vibrated during recording, which duplicates the sound. (This is how grammophones worked. More modern record players have levels of indirection involving electric current, but the principle is the same.)

[smoothmoniker]

Originally Posted by Catwoman

what I don't get is how movement translates into sound? is sound a movement? are sound waves tangible?

Yes!

In a manner of speaking. Picture a stone dropped in a flat pond of water. The stone sends out waves of water in circles from it's impact point. The waves are alternating zones of high water level and low water level. Make sense?

Sound functions in much the same way. Instead of a stone in a pond, picture a person clapping in a room. Waves of air pressure move out from the hand clap. The waves are alternating zones of high air pressure and low air pressure. This happens very, very quickly - hundreds of times per second for most sounds.

The more times per second that the air changes pressure, the higher the pitch of the sound. The bigger the difference in pressure between the high and low point, the lounder the sound.

I'll skip records, someone else can probably answer that more accurately than I can. I was born too late :-)

How?? How is the signal saved in magnetic dust? Do you just get a pile of crushed magnets and sing into them?

A microphone takes that wave information from the air pressure (high and low pressure) and converts it into high and low levels of electricity running through a circuit (that's a whole new topic ... ), and that circuit runs into a small electromagnet (the tape head). Electromagnets have higher or lower strengths based on how much electricity is being run through them.

The magnetic dust on the tape reel is pulled past the electromagnet, and the dust picks up the strength of the electromagnet, and stores it as it's own magnetic field information. The stronger the electromagnet was at the time the tape went past it, the stronger the dust's magnetic field will be at that spot.

So now, follow the chain of events. You clap, sending out waves of high and low air pressure. A microphone changes this in to waves of high and low electricity in a circuit. The electromagnet creates a higher or lower magnetic fields based on the amount of electricity. The tape dust being pulled past saves an imprint of the strenght of the magnetic field from the tape head (electromagnet).

To play it back, you do the exact opposite. The tape moves past a much weaker electromagnet, so weak that the dust from the tape changes the strength of the electromagnet (tape head). This translates into changes in the electrical circuit moving through the tape head. This runs into an amplifier to increase the energy level, while preserving the wave information. Finally, the elctricity pushes your speaker cones in and out, which creates high and low waves of pressure in the air around them, which you hear as sound!

whew. You just got my first 3 lectures of each semester for free! don't worry, my students don't get it either.

-sm

[glatt]

Originally Posted by Catwoman

How?? How is the signal saved in magnetic dust? Do you just get a pile of crushed magnets and sing into them?

It gets complicated, and my explanations are an over-simplification, but here goes:

If you understand how a speaker works, a microphone works basically the same way, but in reverse.

Sound waves from your voice hit a paper cone or membrane which is attached to a coil of wire. That wire is in a magnetic field. The membrane vibrates when your voice's sound waves hit it, and so does the wire coil. When the wire coil moves through the magnetic field, a current is created. I don't know why a current is created when a wire is moved through a magnetic field, it just does. That's how generators work, incidentally. The coil vibrates in a certain way, and the resulting current has a pattern to it. A signal. That signal goes through bunch of circuitry, but basically it goes to the recording "head" on the tape recorder. The recording head is like an electromagnet.

An electromagnet is a loop of wires that has electricity passing through it which causes a magnetic field. They use huge versions of these things in junkyards to pick up cars with cranes and move them around and drop them. Anyway, the recording head, which is basically an electromagnet, pulses a magnetic field that varies in intensity with the strength of the electric signal that comes from the microphone. This pulsing field rearranges the magnetic dust on the tape as the tape slowly travels by. You end up with a tape that has a pattern of strong magnetism and weak magnetism in different areas.

When you want to play the tape back, another head which is basically also just an electromagnet will read it. This electromagnet is turned off so that it can pick up the signal. The magnetic signal on the tape goes past the "coil" of wires that is the playback head, it is a mganet that moves in relation to the coil, and it creates a signal. That signal goes to the amplifyer and then to the speakers.

As you can see, there are two basic principles at play here. The idea that you can create electricity by passing a looped wire through a magnetic field and it's inverse, that you can create a magnetic field by passing electricity through a looped wire. Most of what we do with electricity in this world comes from these principles.

I'm just typing this stuff off the top of my head, so I hope it makes sense. There are probably better places to go that will explain this. LikeHow stuff works

Edit: I type too slow.
Edit again: You can stand on sm. He knows more about this than I do, I didn't know the playback head had electricity passing through it. I thought it was probably totally passive.