next topic »

[on:]

Hello peeps! been a while since i posted on here!

anyway, i'm about to start work on a project based on the tutorial about led colour mixing with 3 potentiometers )this one http://www.arduino.cc/en/Tutorial/LEDColorMixerWith3Potentiometers ).

basically i intend on taking an audio signal and split it into bass, middle and high frequencies using some simple filter circuits. with these three frequencies connected to the analogue inputs instead of the potentiometers, i hope to drive the rgb led in time with the music, like an old colour organ.

has anyone tried this sort of thing before? i havent got the parts yet, but i'm not sure if i'll need to amplify the audio signal with an LM386 ic.

cheers,

bod.

[Reply #1 on:]

that's the digital version of the old 'color organ'. Design wise, a simple AC colour organ (as in these kits or this schematic) will be much easier to realize, cheaper and much brighter!
You would need thousands of dollars of LED's to make something as bright as a $20 colour organ. And that is only a very slight exaggeration.

Doing it on an Arduino will require some audio filters for the input, to 'select' audio within a certain frequency range, filter this into DC and pass it to an analog input. For design simplicity you should probably look for a passive R/C filter-- just google those terms. It's really unlikely that you would need an LM386, as the design problem here is not to amplify thw audio signal to  higher power level, but rather to break the audio down into separate low-power signals that represent each frequency band.

If you do end up needing an op-amp, it will be the low-power instrumentation variety, like a TL 072... with some resistors and capacitors, the op amp can become an 'active filter' that can pick out any particular range of frequencies you like.

good luck

D

[Reply #2 on:]

thanks for the tips on the passive RC filters daniel! its appreciated.
the intention of the project is not to make a colour organ but its the effect that i'm hoping to produce, as i'm using the led to indicate that the code and frequency imputs work, before implementing the idea into yet another project, that requires sound to drive motors and relays.

i was playing arround with filter circuits this morning, but really could do with an osciliscope to make sure its right.

cheers,

bod.