Hey guys. While I am still waiting for the last of my Nixie parts to get here, I've been trying to get one of my more personal projects goin. If you saw my thread about the LED organ, I never quite managed to get it to work.. Maybe. Not correctly atleast. So I decided to just learn about frequency filters and make some kind of device myself.

The goal is, make a 3 or 5 filters. From low to high. To start out with and get a hold on what I am doing, I want to get the low working. After putting in some research, it is much simpler than I thought..

What do you think of this circuit? Essentially repeated and slightly changed values for however many spectrums I want. I apologize for the shady paint skills

Vin is the audio signal

 

You show a simple RC 1-pole filter which has poor frequency discrimination (just 6-dB/octave rolloff above the corner frequency). You likely will want to use a 2-pole or higher active filter to get reasonable frequency selection, especially if you want a band-pass response. An easy way to design such filters is the FilterPro free filter design software from TI.

 

Ah, wonderful!
So say I had a more sophisticated bandpass filter with more poles, would this work?

 

Ah, wonderful!
So say I had a more sophisticated bandpass filter with more poles, would this work?

It should flash the lights in response to the frequencies of the music selected by the filter. You would need an adjustable gain to adjust the sensitivity of the circuit.