LED With Sound

[Dem Pyros]

How would i control a bunch of LED's based off of sound?

AKA how would i plug my audio output from my computer into *something* that would light up (alter the LED's voltage) depending on the amount of sound?

[xmastree]

with one of these (http://www.skycraftsurplus.com/index.asp?PageAction=VIEWPROD&ProdID=431) or something similar.
Or look for an LED VU meter (http://www.google.co.uk/search?q=LED+vu-meter).

[Nagoshi]

http://www.ovelha.org/pasteler0/2005/12/06/howto-blinking-leds/
And
http://www.runtimeerror.net/blinky/index.html

The first one is using a special component that tend to stop workign after a while (the TIP31), and if you decide to plug in or out your jack while power is sent to the sound card (basically, when the computer is powered up), it will send power through the wrong lines and end up buzzing the TIP31.

The second one is using a 9V battery and two transistors along with a couple of resistances.

I wanted to do a similar thing too, but I dont know how I would make it, with the TIP31 or with the resistances, for the best functionality.

EDIT : Just looked at xmastree's post that he did right before me... the LED VU meters are those volume-detecting lights we can find in some amplifiers. They kinda work like those dials we find on some radios and old amps, but with LEDs. The links I gave are for LEDs that blink on light, one channel = one blink on how many LEDs that are jacked to that line.

[xmastree]

The first one is using a special component that tend to stop workign after a while (the TIP31),LOL, what's 'special' about a TIP31? It's just a bog standard audio power transistor...

[Dem Pyros]

Well basically what i want to do is make my own VU meter using an array of LED's, so suggestions/wiring diagrams would help

[Dem Pyros]

Explanation and lists of components would also be incredibly helpful

[xmastree]

Did you look at the second link I suggested?

An LM3916 (http://www.national.com/pf/LM/LM3916.html) is what you need.