taking a sound signal to control LEDs

[foxfan19]

I have been trying forever to get LEDs to play with my computer speaker system. I first tried this and i had a short in the wiring and blew up my speaker amplifier. I then purchased a headphones amplifier. (this way i could control the brightness of the LEDs and the sound being produced, and not have to buy another $150 set of speakers if i had another short in my new system.) Since the headphone amplifier did not have quite enough juice to light the LEDs to the point that i wanted them. i tried to join the signals from 3 of the channels, and left a 4th channel as an output for sound. I had everything wired up and i was testing my design. HOWEVER, it didn't work very well. It started out fine, but within a few seconds the LEDs began to fade. I am now trying to figure out the best way to either fix my design or make a completely different design. Would it be easier to use a transistor as an amplifier? and if so how could i acomplish that? I am very new to the subject, so please do not get mad at me for being dumb.
thanks

 

[Torben]

Hi there, and welcome to the forum.

I'd recommend googling for the LM3915 datasheet and reading through it. The LM3915 is a dot/bar display driver IC which is easy to hang off a voltage source (say, a speaker wire) to rig up a VU meter. The datasheet contains schematics for various simple projects such audio VU meters, vibration meters, etc. which you can make using the chip.

If you want to do stereo, you'll need 2 of them.

I'll warn you that if you're new to this then the datasheet may seem daunting at first, but it does contain a lot of information and the examples are helpful. And as always, if you run into problems or have more questions (which you will, trust me) feel free to post again and we can give you a hand.


Good luck,

Torben

 

[audioguru]

You should never drive LEDs with an amplifier. The output of an amplifier is AC but LEDs use DC. The AC will destroy LEDs. The unsymmetrical load of LEDs will destroy an amplifier.

You should never connect the outputs of amplifiers in parallel. They fight each other and get damaged.

Use DC with an LM3915 LED driver IC. Use the peak detector circuit shown on the datasheet.

 

[Renegade_turkey]

Using a LM324 will work great for using an Op-Amp.