Music Controlled LEDs question

[Cinderella]

Hello, I'm Cinderella ,very happy to be here to discuss my problems and questions with all of you .I f you can help me with my doubt,
That's very nice.

First, thank you for taking the time to read my post.

I know there are tons of examples of music driven LED circuits out there, but they mainly control just one LED or one string of them. I want to make a circuit that will control quite a few LEDs, with each LED at a different range of frequencies.
I figured there must have been a digital way to do this too, but I much prefer the analog approach.
To do this, I am planning on making an array of band pass filters. Each filter would drive a different LED. There are the LED models from
kynix semiconductor, like SML-LX1110UPGC-ATR ,ML-PM01-0090 and etc. Here is the datesheet:
http://www.kynix.com/Detail/1118730/LXML-PM01-0090.html (or string, or something else)... through a BJT perhaps? Here is a quick sketch of what I am thinking.
As far as the comparators, I didn't really know what I was putting there yet, but I knew I had to have some sort of amplifier. So I just put them there for examples sake.
I might add in a high and low pass filter in the end, but I'll decide that later.
Anyway, would this work? I am wondering if you have advice for me, or maybe some different tricks that could reduce the complexity of this project. Are there certain things to watch out for, such as my source not being able to supply enough power to my filters, ect?

Any help would be greatly appreciated!
Thanks in advance! I really appreciate any help!

---

circuit.png
Description:
Filesize:	18.95 KB
Viewed:	357 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

---

[PHOBoS]

Looks like you already figured some thing out but here are some guidelines
to get a nice working set of music controlled LEDs (light organ/color organ):
1. amplification: most of the time you have to work with a low signal of maybe a couple 100 millivolt but because you need to process it
and in the end drive LEDs it makes everything a lot easier if you amplify it to a couple of volts.
2. filtering: as you mentioned yourself: "I want to make a circuit that will control quite a few LEDs, with each LED at a different range of
frequencies. To do this, I am planning on making an array of band pass filters" Since you are not building a passive device I would suggest
active filters.
3. rectifying/smoothing: if you would use the signal out of the filters directly to control some LEDs they would just flicker a lot. By smoothing
this signal out you will get something that is much more pleasing to the eye. Basically an amplitude follower.
4. buffering: you need some current to drive the LEDs and because of the previous step you will probably have to add some buffers.

You mention comparators which can be used but then you will get LEDs that are only blinking on or off, although you could add some smoothing
again to have them fade in/out a bit. But I don kow if that is the effect you want. As for the power source, the circuit itself will not consume a lot
except for the current needed to drive the LEDs, so it depends mostly on how many LEDs you want to use and how bright you want them to be.


for an example of a circuit that works very nice (I built one myself although I might have changed some component values) you could take
a look at this circuit: http://makezine.com/2010/10/18/circuit-skills-led-color-organ-spon/

[Cinderella]