Making something? (Sound Channels to voltage)

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Making something? (Sound Channels to voltage)

Post by Kurt_ » Fri Jan 19, 2007 4:08 pm

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We've all seen it. The little bars that go up and down as the volume of each channel (I think it's each channel, maybe it's different frequencies) increases and decreases. Forthose who haven't grasped what I'm talking about yet, it's the bars under the track time.

What I plan on doing (if it's already done a link would be nice) is translating these bars on winamp or other media player (Windows Media Player, definitely NOT Itunes, etc.) into voltage.

This information will be relayed via computer (usb, maybe) to electromagnets below clear plastic tubes. These tubes will have magnets inside, of similar polarity, so as the sound of the channel (or other) increases, the voltage going through the electromagnet increases, causing the magnets (coloured? Might as well make it colourful!) to rise and drop to the music.

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I hope to make this my first hackaday sumbmission if all goes well. Any and all help (Including continuous if you're nice) will be much appreciated.
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Post by *o* » Fri Jan 19, 2007 4:16 pm

this seems fairly simple.

use an analog signal (3.5mm jack) use a bunch of crossover to separate the frequencies and then once each frequency is isolated just use some beefy transistors to attach each coil to a reasonable high voltage power supply...or something like that
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Post by Kurt_ » Fri Jan 19, 2007 5:37 pm

1) How will I seperate the frequencies? Is there a part that will filter a certain range only?

2) How will I boost the outputted frequency from the magical part? Would a standard Amplifier circuit do the trick?
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Post by tom61 » Fri Jan 19, 2007 5:53 pm

A rather novel idea that you have.
Kurt_ wrote:1) How will I seperate the frequencies? Is there a part that will filter a certain range only?
A bandpass filter for each frequency will be needed.
2) How will I boost the outputted frequency from the magical part? Would a standard Amplifier circuit do the trick?
Yes, an standard amplifier will do. Depending on the size of magnets, coils, and tubes, as well as the viscosity of the liquid, you might be able to use an off-the-shelf amplifer designed for stereos.

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Post by Sir Games-A-Lot » Fri Jan 19, 2007 6:53 pm

While I'm not not entirely sure how to set up the translator, I do have sugestion for the magnet tubes. The way you have it set up now, it would seem that the earth magnets will be prone to stuttering during their travel since they will be forever trying to flip themselves over (due to their polarity). To fix this I would do this: Fill the tubes with a liquid, then connect the earth magnets to floats with the polarity opposite to the EM coils facing down. This will allow the indicators to move up and down smoothly, all be it with a little drift (could be fixed by tweaking the float and liquid forumla).

Just a random musing.
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Post by Kurt_ » Fri Jan 19, 2007 7:22 pm

I was thinking I'd have a small hole in the tube, and a 1 way valve, so they drift down slowly, but go up quickly, like the bars on winamp do. They'd still stutter though... A liquid wouldn't move them up fast enough.

Maybe just a very close fit will do the trick, I'll find tubes then trim the magnets to size.

EDIT: I'm looking around, and bandpass filters are rather expensive, and have a very low range. Is there any source of cheap, higher range ones?
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Post by Sir Games-A-Lot » Fri Jan 19, 2007 8:08 pm

Wait, wouldn't you need two one way valves, one for intake one for outflow (right now it would seem we only have an "out" valve and no supply of air)? (I know zip about pneumatics so don't pay to much attention to me :wink:)
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Post by gannon » Fri Jan 19, 2007 8:19 pm

So, you want to build a spectrum analyzer?
You can either have plugins for each media player and say, output each spectrum on the parallel port, or just process the audio output in hardware.

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Post by Kurt_ » Sat Jan 20, 2007 10:10 am

@ Sir Games-A-Lot:
There will be generous slits near the top of the tubes. However, in this post (for now, at least), I would prefer we talk about the electronics, as the tube is rather easy to create.

@ Gannon:
Yes. But instead of a screen display, a physical set of shifting bars.
And I know very little about computers and what they can output and such. I think the standard speaker jack idea will be best for me, as I don't need a high-quality ub3r seperated signal or anything of the sort, I'm just moving bars up and down.

Still looking for cheap high-range bandpass filters. Would a small range every couple "units" of hz work? or would I need to cover all the frequencies for an 80% or higher accuracy?

Like this:

Image

ALso, the human ear can hear 6hz to 12000mhz or something like that right?
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Post by bicostp » Sat Jan 20, 2007 11:17 am

It's 20 Hz and 20 kHz, according to Wikipedia.

I vaguely recall using a capacitor and a coil of some sort in a speaker box to seperate the midrange and high frequency audio (for optimal tweeter and subwoofer performance), but I forget exactly what to use. Look up some speaker-box building sites. (Side note: those woofer boxes kids put in their trunks are all wrong for the cones they put in. They really make the woofers sound like feces. We've got a 12 or 14 inch woofer in a really big box and it sounds better than any car box. You can't slap a speaker in a box and call it a day if you want it to sound its best; you have to do some thinking!)

Since audio signals = analog electricity, couldn't you hook up an amplifier and use some of those capacitor-coil things to seperate frequencies?

The little yellow test strips on batteries would make decent displays, since they're designed to fill up depending on the voltage they get. I think there's a project on Hack-a-day or something that shows a parallel port CPU monitor made out of one of those.

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Post by timmeh87 » Sat Jan 20, 2007 12:18 pm

ALso, the human ear can hear 6hz to 12000mhz or something like that right?

that would be terrible, computers would probably all emit this high pitched buzzing noise all the time.

its not hard to make a high pass filter, or a low pass filter out of inductors capacitors and resistors. im guessing here, but i think youd need to make a high pass an a low pass filter for each band, to define the upper and lower portions of the band.

so like. a low pass filter that cuts at 1010khz and a high pass filter that cuts at 990khz would give you a 10khz wide band centered at 1000khz.

of course, the behavior of filters like this is more of an exponential dropoff than a definite 'cut'.

furthermore, they wouldn't be passing a voltage related to the closeness of the frequency to the middle of your band, like you want... they would literally be passing the actual audio in that range. which means half the time your floaty magnets will be pulled towards the coils. the net effect would probably be no movement or floating.

maybe rectifying the audio after it is amplified?

no offense or discouragement kurt, but this isnt an easy 2 hour project. i see you start crap like this all the time and never finish cause you get bored. something im entirely guilty of too. maybe you should finish your portable first....
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Post by nitro2k01 » Sat Jan 20, 2007 12:41 pm

The name for this kind of thing is "graphic equalizer" "Spectrum analyzer". How important is it that your equalizer is constructed around moving physical items?
The standard way of doing it would be with LEDs. But either way I'd recommend to use audio input rather than letting it be computer controlled.
Also, check this
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Post by gannon » Sat Jan 20, 2007 3:01 pm

nitro2k01 wrote:The name for this kind of thing is "graphic equalizer".
I think you're confused on what he's talking about, he meant the spectrum analyzer in winamp, not the equalizer.

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Post by nitro2k01 » Sat Jan 20, 2007 3:35 pm

gannon wrote:
nitro2k01 wrote:The name for this kind of thing is "graphic equalizer".
I think you're confused on what he's talking about, he meant the spectrum analyzer in winamp, not the equalizer.
No I didn't. I always thought you could call a spectrum analyzer "Graphic equalizer" even if I thought it was a strange name. Sorry...
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Post by bicostp » Sat Jan 20, 2007 3:36 pm

Equalizers let you adjust the volume of audio frequencies. Analyzers are the little colored bars that jump up and down.

Don't they make chips that can do this for you? :?

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