Author Topic: Wave Display Circuit  (Read 1122 times)

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Offline CybranTopic starter

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Wave Display Circuit
« on: March 18, 2010, 09:23:49 PM »
I've always been fascinated by the Scope visualization in the Windows Media Player, and I've got some idea to make a circuit that could duplicate it onto a screen of some sort. Anyways, on with the questioning:

1. What exactly do you call a wave similar to the Scope Visualization in WMP? I've been calling it a Vox wave, but I have a feeling this isn't right.

2 What are your ideas for a circuit that could take a sound wave from say, a iPod headphone jack, and create visualizations on a screen. I suspect you use a circuit that sends different voltages or waves down different pathways, which are then displayed in columns on a screen.

3. What sort of screen would function best with this circuit? A computer monitor? A large LED array? I have a feeling the LED array would be easier.

Anyways, I don't think I'll build this until I have money, so all I really need are theories, though any DIY projects with similar ideas would be nice. Thanks for the help!

Offline cyberfish

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Re: Wave Display Circuit
« Reply #1 on: March 18, 2010, 10:04:28 PM »
Fourier transform of the signal?

I'm not sure if there's a way to do that with circuits, though. You will need to build A LOT of filters.

Probably easier to do it on a microcontroller.

Offline Soeren

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Re: Wave Display Circuit
« Reply #2 on: March 18, 2010, 11:18:34 PM »
Hi,


1. What exactly do you call a wave similar to the Scope Visualization in WMP? I've been calling it a Vox wave, but I have a feeling this isn't right.

You're right it isn't right ;D

Either you call it an oscilloscope trace, an instantaneous voltage display (a bit "artsy" though), or an amplitude/time display (If you are a 5th grade physics teacher).

If you wanna describe just the waves shown, it can be just about any waveform, but any waveform is a sum of sine waves of different frequencies (except a pure sine, which is only one frequency but cannot be found outside a lab or similar controlled environment).


[...] I've got some idea to make a circuit that could duplicate it onto a screen of some sort.

2 What are your ideas for a circuit that could take a sound wave from say, a iPod headphone jack, and create visualizations on a screen. I suspect you use a circuit that sends different voltages or waves down different pathways, which are then displayed in columns on a screen.

Oh well, you should fully explore your own ides before asking for other peoples same.

But here's a hint... It's called an oscilloscope and you don't need to reinvent the wheel, just buy an old 'scope and hook it up.
One (1) voltage send through one (1) "pathway" and displayed as one (1) trace.
A fast timebase, persistence of the eye (and of the phosphor coating on a 'scope) is what makes it look like several traces.


3. What sort of screen would function best with this circuit? A computer monitor? A large LED array? I have a feeling the LED array would be easier.

The 'scope allready comes equipped with a screen.

If you really wanna make an inferior circuit, an LM3915 in dot-mode can be multiplexed onto eg. 10 columns of 10 LEDs, to create a very low resolution 'scope.
Look at this YouTube video

If you google "LED Oscilloscope" you'll get tons of circuits, all of them probably with LM3914, as this is linear, but for sound, the logarithmic LM3915 is better suited (same pinout, so they can use the same PCB).

Good resolution and fairly simple construction can be done with a LASER module, a motor with a speed regulator made for the purpose, 6 or 8 small mirrors, a small worn out speaker, a piece of rubber "foil" or similar and a small amplifier made for the purpose. The "screen" is whatever you point the output at.
(Way before LASERS, we used regular lamps and lenses to get a small dot of light).


Anyways, I don't think I'll build this until I have money, so all I really need are theories, though any DIY projects with similar ideas would be nice. Thanks for the help!

You won't need that much money. You could get an old oscilloscope for perhaps $20 (since it don't need to be in any particular shape besides being able to show a trace). 100 LEDs, an LM3915 an op-amp and some "glue" is not particular expensive and the LASER version needs eg. a cheap LASER pointer, besides what you can probably mostly get from a dumpster (old VHS recorders have motors and stuff) and a glazier (if that's the right name, will probably give you the small pieces of mirror you need for free, as he bins much larger pieces regularly.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline CybranTopic starter

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Re: Wave Display Circuit
« Reply #3 on: March 20, 2010, 12:49:21 PM »
I had no idea you could buy these. Tanks!
Though when I Google "Oscilloscope" I find machines that range in the thousands, not 20$
« Last Edit: March 20, 2010, 12:52:09 PM by Cybran »

Offline waltr

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Re: Wave Display Circuit
« Reply #4 on: March 20, 2010, 01:44:51 PM »
I had no idea you could buy these. Tanks!
Though when I Google "Oscilloscope" I find machines that range in the thousands, not 20$


Check Ebay. You can get a hobby usable O'scope for a few hundred at most.

Offline CybranTopic starter

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Re: Wave Display Circuit
« Reply #5 on: March 20, 2010, 01:51:27 PM »
Did that when I posted above message. Still over my price range.

Offline chelmi

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Re: Wave Display Circuit
« Reply #6 on: March 20, 2010, 06:06:20 PM »

Offline Soeren

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Re: Wave Display Circuit
« Reply #7 on: March 20, 2010, 10:39:05 PM »
Hi,

Check this one: http://www.sparkfun.com/commerce/product_info.php?products_id=9484

Nice find! Cheap enough to go into certain projects ;D


Cybran <- I forgot to mention the really cheap method - download a "PC 'Scope" (watch out, they're not all freeware). It uses the sound card input as a "free" oscilloscope (not counting the price of the PC). At least good for knowing if a physical oscilloscope might be the thing for you.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

 


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