Audio Controlled LED Chaser using Bandpass Filters and RGB LEDs

[ClncyFshSlayer90]

Well, I have decided to take on a rather ambitious project to start out my 2016, but I am at a loss on where to start. I know what I want the project to do, and have a decent understanding of what needs to be done, but could use a little guidance in what circuit layouts would work best.

I want to make a circuit/combination of circuits that will drive a series of RGB LEDs in sequence, based on the target audio range (treble, mid, bass). I will be using a car stereo pre-amp outputs for my audio signal so I am working with a line-level audio input.

Essentially, I want to separate my audio in to three channels (treble, mid, bass) and have each channel run it's own sequencer circuit that will run a single leg of the RGB LED. The idea is that all 3 sequencer circuits will be running at different timing intervals, producing a completely random display of colors in the LEDs depending on when 2 or 3 sequences align with eachother. Ideally I would like the LEDs to fade out as it advances to the next one in sequence, that way I have a better variance of color as the sequences will align more often and at varied intensities at each leg of the LED.

Any guidance would be greatly appreciated. I have no problem messing around with different layouts and combining different circuits to get the desired effects, I just don't know what types of circuits I need to be looking at to produce each step efficiently.

I have an engineering background and do have a fair amount of experience building circuits, but need some advanced thought on this one.

 

[large_ghostman]

I would probably start with looking at band pass filters and decide if you want to go down the bunny hole into the world of micros or keep it analogue.

 

[audioguru]

How many LEDs in each of the three chases? Do you want only one LED in a chase to be lighted at a time?
The filters are easy: Lowpass, Bandpass and Highpass.
I have used CD74HC4017 digital ICs for chaser circuits.

 

[ClncyFshSlayer90]

For the design, I will just say it is a single LED on each run, but I will be expanding it well beyond that, and will build a circuit specifically to power the LEDs. I will likely have in the neighborhood of 10-20 LEDs per run (100-200 total) once I have the meat and potatoes figured out.

I do not have any experience with digital circuits, and at this point I have only used analog; however, I am certainly open to learning something new, especially if it will make this project easier.

For an analog type design, I have included a high level flow chart of what is in my head right now. Though there are probably a multitude of ways to simplify this idea.

Please ignore the error in naming. It is a BJT delay circuit using a BC547, resistors and capacitors.

The link to the circuit is here: **broken link removed**

 

[audioguru]

You need only one bandpass filter and it is for the mid frequencies. The lows need only a lowpass filter because there is no audio below about 20Hz and the highs need only a highpass filter because there is no audio above about 20kHz.
Peak detector circuits are simple.
Why use three 555 ICs when you can use one CD4584, 74C14 0r CD74HC14 which can make up to 6 oscillators. Each oscillator uses one resistor plus one capacitor.
Why use 30 fade-in and fade out circuits when you need only 3? One for the common ground of each group of LEDs that is clocked by the same clock signal that feeds the CD4017. My chasers do that to blink each LED for a moment using low average current instead of jumping from one turned on LED to the next turned on LED. My blinking LEDs also pause for 2 seconds after chasing around 3 times then the AA's battery lasts for months even when the chaser runs every day and night.

A CD4017 has a fairly low output current which is why I used CD74HC4017 ICs that have a lot more output current.

 

[ClncyFshSlayer90]

That would be why I brought my questions to a forum with people in the know. I am a few years out of the loop on my electronics courses in college and thought I would get back in to it. I have been thinking through what I want this set-up to do, but do not necessarily know how to go about doing it. I just came back to circuits I have done, with varying degrees of outcomes, in the past and started linking things together. I know there was something that could be done to make this a little easier and much more streamlined, but I do not know what those things are.

Any thoughts (links to schematics are greatly appreciated) would help me a lot. I have no problem designing the circuits with some google learning, but do not know all that I need to to complete this projects, hence the reason I am reaching out.

Here is what I have put together so far.

Audio Filter: A variation of the below schematic

Peak Voltage Detector: A variation of the below schematic

LED Fader: Something like the below schematic

These are the only circuits I have managed to scrounge up at this point, but like I said before, I am sure there are components that I have never worked with that can simplify this deal immensely.

 

[ClncyFshSlayer90]

Due to input from a couple of forums, I have some edits to the flow of my circuits. In lieu of using 3 555s, I want to try to use a single CD4584; in lieu of a CD4017, I want to try to use CD74HC4017s; and finally, in lieu of 30 different fader circuits, I would like to use a single fader circuit on the common ground of each color group of LEDs.

I have no experience in the use of a CD4584 or the CD74HC4017. If it is not too much to ask, even a simple hand drawn schematic would be great. I can figure a lot of it out, but a quick drawing of the connection between the CD4584 and the 3 CD74HC4017s would help a lot. And including the layout of the fader circuit with the common ground would be amazing too.

In summary, if I can get a schematic starting at the output of the audio filters and terminating at the lights, that would be great. I think I can conjure up the filter circuit and the LED driver circuits, but the timer and decade counter circuits I have trouble with.

 

[audioguru]

Here is an oscillator make with a CD4584 Cmos Schmitt Trigger inverter. The resistor is 10k minimum to 10M. There are 6 inverters in it. The unused inverters should have their inputs connected to 0V.
The output of each oscillator connects to the CLOCK input pin 14 of a CD74HC4017 and both ICs should have the same power supply voltage that is +5V or +6V.

 

[audioguru]

Here is a CD74HC4017 with an oscillator and LEDs:

 

[ClncyFshSlayer90]

Well I think I have a fair amount of this figured out now. But I do have some specific questions on a few components. I have created a layout that shows each individual component of the series. Does this look about right? Any glaring errors?

To power the whole thing, I will be using a computer power supply, so the 12V and 5V connections will be simplified.

If anyone can provide some additional input on this, that would be great, as I am a bit stumped at this point.

 

[Mikebits]

For your first block, there are IC's made for that very purpose. Google turned up quite a few. Here is one example:

• General Description
  The NJU7505A is a band pass filter for audio spectrum analyzer display.It consists of high and low band pass filters, CR oscillation circuit, control circuit and DC transfer circuit.Each band pass filter using the switched capacitor filter technology operates at the shared time by 5 bands which filter constant is switched by the internal clock.Therefore, the audio signal shared of 5 bands is output from a serial output terminal.The 10 bands version using the double by the cascade connection is prepared.

Data sheet: **broken link removed**

 

[audioguru]

Now you tell us you will use runs of 10-20 LEDs. The kind on a flexible strip with current-limiting resistors included and powered by 12V? Then the total will be 3 x 10 x 20= 600 LEDs?

Now you tell us that you want each 4017 to sequence to the next string of LEDs when there is a sound peak detected in its frequency band. So the clock pin of each 4017 is triggered by pulse and not is continuously sequencing by the oscillators I showed.
The 4017 clock input already has a Schmitt Trigger so the CD4584 IC is not needed. The CLOCK input can be triggered from the peak detector.

The CD74HC4017 has a maximum allowed supply voltage of only 7V so an ordinary CD4017 should be used since its maximum allowed supply is 18V. With a 12V supply the output current from a CD4017 is about 15mA which can drive a little high current transistor such as a BC337 to drive each run of LEDs.

The ramping can be done with a small power transistor for each CD4017 pile of LEDs such as a TIP31. With the slow ramping each TIP31 will get hot but not hot enough to need a heatsink.

If the sound source is voices or music then the peak detector will sequence the CD4017 ICs very frequently. Then there is nothing to trigger the very slow ramping down (no ramping up?) except when there is a few seconds of a pause in the sound.

 

[ClncyFshSlayer90]

Thanks for the input all. I have opted to scrap the whole thing and go with Arduino sequenced lights.