Design DIY LED cluster

jdenmark100

Member
So I am looking at making an LED cluster that will bump with music with a typical college dorm room stereo. Yes, I know there are products that you can buy that use sound to trigger the light. What I want is something that takes the signal that tells the speakers to bump and splice in the LED wires that will light them up. Is it as simple as soldering them together and adding + and - wires and just putting them into the speaker ports? or do I need something else. I am not looking for complexity I am just trying to keep it stupid simple without special effects. Just bump with the music.

thanks
 
You would have to ballast each group with a resistor, diode, and cap. The LED works at a specific voltage so the resistor would simply be changing the current the led sees as the voltage goes up. The diode would protect the LED from spiked inverse voltage and with the cap would smooth the effect out. You would also have to calculate the peak voltage coming off the amplifier and use that to determine the peak current going to the LEDs so you don't pop them. (This would be used to figure out the value of the resistor.)
Something to consider- since these circuits will cut-in at a specific voltage, you will be introducing distortion in your audio.
 
Here's a couple of videos of some light reactive LEDs I put together.

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I got lucky, the bookshelf amp happened to peak at 20V, the diodes are rated at 18V and the voltage drop across the bridge rectifier I used was 2V. It was a pretty lucky scenario though, the LED arrays were available to me for free for a pair, I believe at the time they were available they ran $300 each, and the amp just happened to have the right output power for the project, and I had it laying around.

I did it connecting a full wave bridge rectifier to each output and the LED arrays to each rectifier, that ensured the LEDs only saw DC and gave me the needed voltage drop to not burn out the diodes. The alternative is to do what JD said, I would leave out the cap personally because the effect really shouldn't be smoothed.
 
You would have to ballast each group with a resistor, diode, and cap. The LED works at a specific voltage so the resistor would simply be changing the current the led sees as the voltage goes up. The diode would protect the LED from spiked inverse voltage and with the cap would smooth the effect out. You would also have to calculate the peak voltage coming off the amplifier and use that to determine the peak current going to the LEDs so you don't pop them. (This would be used to figure out the value of the resistor.)
Something to consider- since these circuits will cut-in at a specific voltage, you will be introducing distortion in your audio.

I build guitar pedals as a hobby. We use diodes and LEDs to create distortion. You do not want to put this on your speaker lines. "Why" off the line level signal and use a kit of some sort, much safer.
 
I should mention that bookshelf amp is fed by a separate line level signal and is completely independent of the speakers and amp.
 
Thank you all for the input. Over christmas break I will tinker with a few things to see what I can come with. There is some very good information here
 

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