Random LED visual feedback for Echo Base audio output

[pgorey]

I'd like to create an LED circuit that provides visual feedback for an audio signal - specifically, I'm building an Echo Base and I'd like to wire up a string of LEDS (different colors) all around the enclosure to light up in random order based on the output signal of the pedal so it lights up randomly on all LEDs with each transient off of the pedal output.  The big picture is that I'm going to design a Cosmos / Space graphics theme and want the LEDs to blink like random stars twinkling.  I know it's completely unnecessary and even a bit silly but I think it would look super cool..  Is this something that is relatively easy to do?

[EBK]

How many LEDs?
Are you looking for a random sequencer which advances on each detected audio peak above a fixed threshold? Or something based on a zero-crossing detector?
Or do you want all the LEDs to pulse at the same time?
Or do you want each LED to blink at its own random rate, but control the maximum brightness of all blinks based on the signal envelope?

I guess what I'm saying is that you haven't given us enough info to know exactly what you are after.

[robthequiet]

My first thought would be a schmitt trigger into a daisy-chain of counters and bar graph drivers with the LEDs wired randomly. You'd have to clock it, somehow. Also sizing the power supply and filtering would be an issue.

[Ice-9]

You could hve a look at the LM3914 IC's, these can each drive 10 leds and are often used in VU meter circuits.

[vigilante397]

You could hve a look at the LM3914 IC's, these can each drive 10 leds and are often used in VU meter circuits.

I've built a couple VU style pedals using these and they're great. A simple audio buffer/splitter in front helps a bit to avoid signal loss too.

[pgorey]

I can't fit too many 5mm randomly around the enclosure but let's say 10 for this example.  Each one would flash with a single transient of the repeating echo audio off the output so something like this:

Dry signal transient 1 - light LED 1
Echo feedback transient 1- light LED 2
Echo feedback transient 2 - light LED 3 etc...

All LEDs would be full brightness.  What would be cool is to randomize which LEDs get powered by the initial dry and subsequent echo feedback transients so the LEDs appear to be randomly lit but in time with the audio off the effect output.  I think this would be the ticket - " are you looking for a random sequencer which advances on each detected audio peak above a fixed threshold?"

Regarding your signature, I built the Trump pedal - not the Noise Kick Regan Fuzz but the orange Tremendous Fuzz posted about a month ago.  It's a the breadboard Fuzzface kit from Small Bear that I moved to a perfboard.  It sounds good but would rip with a proper tone stack boosting around 3-6k.

How many LEDs?
Are you looking for a random sequencer which advances on each detected audio peak above a fixed threshold? Or something based on a zero-crossing detector?
Or do you want all the LEDs to pulse at the same time?
Or do you want each LED to blink at its own random rate, but control the maximum brightness of all blinks based on the signal envelope?

I guess what I'm saying is that you haven't given us enough info to know exactly what you are after.

[duck_arse]

my vote goes to a led bar-graph VU meter chip driving a dual binary counter, like the 4520, say. this would possibly suit driving a few more leds.

[Kipper4]

"dual binary counter, like the 4520"
Did I jet into another parallel universe?
What the heck is one of them.

[EBK]

Regarding your signature, I built the Trump pedal - not the Noise Kick Regan Fuzz but the orange Tremendous Fuzz posted about a month ago.  It's a the breadboard Fuzzface kit from Small Bear that I moved to a perfboard.  It sounds good but would rip with a proper tone stack boosting around 3-6k.

Glad that mystery is solved, and I believe it was Rich who asked me about it in the first place, so he knows too.   

http://www.diystompboxes.com/smfforum/index.php?topic=116468.msg1079499#msg1079499

[merlinb]

Comparator driving a decade counter. The decade counter drives the LEDs.

[robthequiet]

it lights up randomly on all LEDs with each transient off of the pedal output.

Merlin, so the comparator would clock the counter, no need for clocking device, right? But now I'm thinking that you might want an envelope to sort the spacing of the transients. I think the visuals from would work from taking transients from a nice attack and even repeats. Complex playing might need some filtering, no?

[MrStab]

this idea isn't at all what i thought it'd be from the title and if i understand you right, Pgorey, it sounds like it'd look really, really cool. share a vid if you get round to it!

maybe a quick & dirty way would be to get one of those random flashy-light CMOS hobby circuits (using counters like Merlin said) and sticking a common from the LEDs through a BJT, with the guitar signal driving the Base. that's a really crude suggestion, don't do it. lol

[amptramp]

This sounds a bit like a colour organ that splits the audio into bass, midrange and treble with the crossover points set to give nearly equal output in each range.  Adding a counter to the outputs is good but it may mean you only have a few LED's on at a time.

[pgorey]

I knew you guys would have some cool solutions to try.  I like the color organ idea as well!  I'm going to try to prototype a circuit for testing and then once the circuit is solid, I'm going to add to the Echo Base I just built.  I haven't designed the graphics or enclosure yet so it will be a good contender for this idea.  I love the Echo Base.  It's just a PCB with offboard wiring at the moment but on first firing it up, i was so impressed with the quality of the sound.  Didn't go crazy with the mods thus far - just the standard runaway mode momentary footswitch and the trails on/off toggle.  Really great design on that circuit.  Can't wait to make the output do other fun things with the LED.  Already cool that the bypass LED provides a visual by pulsing with the modulation rate.

I'll be back in a while once I build something for this idea.  Thanks agin guys.  Really thankful for this community.

[amptramp]

A basic but functional colour organ:

http://www.jameco.com/Jameco/workshop/video/ledcolororgan.html

This one is elaborate but has different thresholds for each LED and if you buy bulk parts, it is not that expensive:

http://www.electronicpeasant.com/projects/ledlamps/ledcolor.html

[EBK]

Just want to add that this is a good application for a microcontroller.  You would be able to make your lights do just about anything you want. If you decide to give it a go, be sure to put a shield between the microcontroller and the audio circuitry so you don't get digital chatter on your output.

[pgorey]

That color organ is sweeeeeet!  A little bit much for the space I have unless I get really creative but very cool idea.  What type of micro-controller would you recommend?  Arduino? 

[EBK]

That color organ is sweeeeeet!  A little bit much for the space I have unless I get really creative but very cool idea.  What type of micro-controller would you recommend?  Arduino?

I've used an Arduino Trinket to great effect.  Nice and small, easy to program.
(Used it to drive a 24-segment bi-color LED bar graph display)

[pgorey]

Cool, that could make a really good segway for me into working with chips for DSP / analog hybrids which is eventually where I'd like to go with my building.  I love the classic designs and analog circuitry and will never stop with that but there's also something beautiful about pedals like this: 

https://www.sweetwater.com/store/detail/Canyon?adpos=1t1&creative=175866237996&device=c&matchtype=b&network=g&gclid=Cj0KEQiA25rFBRC8rfyX1vjeg7YBEiQAFIb3b669TX6JPbl4CWXROOlePfqfelt5e9h0xJBOB5rp7ZIaAjuO8P8HAQ

Just curious, what was that LED bar graph display for.  24 is not small so on a mixer or rack gear?

[EBK]

Just curious, what was that LED bar graph display for.  24 is not small so on a mixer or rack gear?

Compression indicator on my compressor pedal:

Sometime, I'll have to make a video of it or something, but basically, it uses a yellow bar to indicate the instantaneous output level on a dB scale, and red bars above or green bars below to indicate by how much it is attenuating or amplifying the input to arrive at that output.
Enclosure size is 1590BS (same footprint as 1590B, but a bit deeper). 
The bar graph itself is this product: https://www.adafruit.com/product/1721
I used this Arduino Pro Trinket microcontroller board, but I could have used a smaller one: https://www.adafruit.com/products/2000 (bought the board before I had a specific plan for it  ).

Cool, that could make a really good segway for me into working with chips for DSP / analog hybrids which is eventually where I'd like to go with my building.

Along those, lines, I'm currently working on a build involving one of these: https://www.pjrc.com/teensy/index.html.  It's basically like an Arduino with a DSP core.  It keeps getting pushed back in my queue in favor of more instant gratification builds though...