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Which IC to use for music reponse Answered

I am looking to get a IC which can control LED's according to the music I am playing.... so I want have LED's on prototype boards...and I wan to control them on/off, change colors etc..according to the music I am playing in that room any help on what and where to get them would be great thanks

5 Replies

greenzellybean (author)2009-01-13

thanks...westfw. I have 5 prototype boards with 50 LED's on each board...so will I be needing 5 IC's? or do I need ot break them into smaller clusters so each IC can control no more than say..25 LED's? thanks

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westfw (author)greenzellybean2009-01-15
Each "channel" of LEDs would take several op amps or components of similar function. The basic principle is:
  • Buffer/amplify incoming audio to convenient levels.
  • Split audio into separate "bands" based on frequency, using "active filters."
  • Detect the volume of each band of audio. The number of "steps" is a design decision; simple "color organs" will have a single threshold, more complex versions will have many steps.
  • Drive LEDs for each channel based on the (instantaneous) volume of that channel.
The degree to which each function requires electronics or chips is somewhat variable. You CAN implement filters in passive components only. Or you could digitize the audio and do the whole thing in software.

Here's a design using only transistors:

Here's one that does it all in software:

Essentially, you're making a "graphics equalizer display" or frequency dependent VU meter. You'd think there would be a chip that did that, but the only one I found that was close was obsolete...

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11010010110 (author)2009-01-15

surface advice to what chips use for a full blown big system bandpass filtrs as needed (not chips) - to filter the band you want to sense envelope filter (not a chip) - to get the changes in volume and not the real KHZ's of sound opamps (lm324 / lm358) between filters analog to digital converter (most can output 8 bit which means up to 256 leds) demux's (to spread the 8 bit output of the adc to actual 256 wires) or gates - if you want a column of leds and not one led lit at a time diodes - if you want to combine different outputs together to single led leds

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Sandisk1duo (author)2009-01-14


right here

but it only responds to bass

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westfw (author)2009-01-13

Most of that sort of things is built up from basic op-amp blocks. An op-amp can be your microphone pre-amp, your bandpass filters, peak detectors, and even LED drivers, and they're cheap and common. But it's a fair amount of work to get from op-amps to a full working circuit. I'm not aware of any "make it all easy" chips for this sort of thing; the closest is probably the lm3914 and related ICs, and it only does level-meter sorts of things. There are literally thousands of different op-amps out there, typically in one, two, or four amps to a package. I'm not sure what the current standard recommendation is. Probably a lm324 ?

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