This was inspired by the sidewalks at Epcot Center that look like ordinary concrete - until night when they light up with different colors. So I took a plain old mini-booster, and retrofitted it with an LED VU meter (with much help from Rob's thread here: http://www.diystompboxes.com/smfforum/index.php?topic=98118.0 (http://www.diystompboxes.com/smfforum/index.php?topic=98118.0)). I haven't edited a video in so long that I forgot how to do it - so here's a demo - complete with crappy unedited playing.
It's all about the lense and the brightness of the lights behind it.
Good guess, but there are no lenses, and no lights behind it.
It's a little hard to tell in the video, but it's 5 separate LEDS.
(http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=49404&g2_serialNumber=2)
When they're not lit, you can hardly see them ('cause they blend with the stone-texture).
(http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=49407&g2_serialNumber=2)
I like me the lights! ::)
Hey,
Looking great. I'd like try something like that myself just for the fun of it. I do have one question though. Does one have to split the original signal into two, and what is the best way of doing it? Any loss of quality in the original signal would be... undesirable. :D
QuoteDoes one have to split the original signal into two, and what is the best way of doing it? Any loss of quality in the original signal would be... undesirable.
The input impedance is about 500K, so you don't need to do anything special to split the signal - just tap off the input jack. It will not load your pickups or tone-suck. In my first try (video above), I didn't even bypass it along with the pedal circuit.
That's awesome!! Could be used as a bypass indicator as well.
Very cool!!! 8)
nice one walt...looks cool. 8)
this is going in my next pedal....i hooked up 9 leds to it.
https://dl.dropboxusercontent.com/u/7464107/ledvu.wmv
and yes it can be used as bypass indicator too, but i like it on all the time.. ;)
nice and simple 1 wire to audio circuit in, ground,9v... 8) 8) 8)
Thanks for the encouraging comments all. Nobody asked how it was done, but I'm dying to tell you... so here it is.
The LEDs are tiny 0603 SMD parts, mounted on a super thin PCB, and glued to the top of the box.
Here's the layout. The one with 5 LEDs is used on the pedal, the other one is the 9-LED layout preferred by DeadAstronaut.
(http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=49425&g2_serialNumber=2)
LEDs on...
(http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=49428&g2_serialNumber=2)
The LED connections are enamelled wire that go inside the box through one small hole.
(http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=49431&g2_serialNumber=2)
The circuit inside the box is a standard through-hole layout of the AN6884 LED driver.
(http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=49434&g2_serialNumber=2)
So here's the LED strip glued to the box with a coat of primer on it.
(http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=49437&g2_serialNumber=2)
Inside the box.
(http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=49440&g2_serialNumber=2)
Then I thought, why not make the driver circuit SMD as well.
(http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=49443&g2_serialNumber=2)
Layout closeup.
(http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=49446&g2_serialNumber=2)
You can just glue the thin PCB right to the chip. The pins are just bent up over the top of the PCB.
(http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=49449&g2_serialNumber=2)
Here's the LED strip and the AN6884 circuit. They are small enough to fit in pretty much any box.
(http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=49452&g2_serialNumber=2)
So I obviously made a few of these while developing the design. Anybody want one? I'm thinking about making a kit with the two PCBs and the SMD parts already soldered on.
With all the pedals in the chain cables are running lengthy. Nothing a little Cornish buffer won't fix. It took me a while to fit it all in and a headache in the end, but I had a lot of fun building it. Mine's not that invisible though... ::)
(http://img703.imageshack.us/img703/6521/mz2h.jpg)
Quad - looks great. Nice work.
I'm having some noise with the meter. It's slightly crackling. Here's the design I used (Rob's):
(https://dl.dropboxusercontent.com/u/7464107/5ledveroDA2013.jpg)
hi quad, crackling?.. ive never had a problem with it
what are you going into at the same time with it..?
Hello,
A Cornish buffer:
(http://4.bp.blogspot.com/-fMYuy0RSqu8/T0Iv5T4z0RI/AAAAAAAAA-U/rB4BC5uLekw/s1600/CornishBuffer.png)
QuoteIt's slightly crackling.
Do you have it hooked up at the input of the Cornish buffer, or the output?
Does it crackle a little bit all the time, or just occasionally?
Did you use all the same values that Rob suggested (10 uF, 220K, 330K, 2.2k)?
Does it only happen within the first minute or two of turning it on?
I heard a slight crackle with mine once or twice, but it didn't continue to happen. I was thinking it might have been just until the 10uF cap got charged up or something.
Quote from: waltk on July 21, 2013, 10:54:38 AM
QuoteIt's slightly crackling.
Do you have it hooked up at the input of the Cornish buffer, or the output?
Does it crackle a little bit all the time, or just occasionally?
Did you use all the same values that Rob suggested (10 uF, 220K, 330K, 2.2k)?
Does it only happen within the first minute or two of turning it on?
I heard a slight crackle with mine once or twice, but it didn't continue to happen. I was thinking it might have been just until the 10uF cap got charged up or something.
I have tried it both ways - IN and OUT with the same result. It starts crackling as the first LED goes out with diminishing signal strength. Yes, I used the same values as depicted in Rob's design. It stays the same (crackle) regardless of duration. There's one more thing I've notice: sometimes the first LED gets stuck (turns on and stays on for a while). It stays on along with a 'hiss' sound, then eventually shuts down.
Have you tried it without the buffer? I'm thinking the buffer is making the hiss - and keeping the first LED on. Here are some things I noticed about the circuit that might give you some ideas...
The input impedance is determined by the two input resistors in series to ground. The datasheet shows a 10K pot forming that input voltage divider, but that would load down guitar pickups and suck tone. I guess that's why Rob used 220K and 330K resistors to make his input voltage divider. Are you really sure you didn't accidentally use smaller values for these resistors? I use 100K and 1M resistors in my circuit - OR a 1M trimpot. This lets more of the input signal through (more sensitive), and also increases the input impedance. With a 1M input impedance, there's no need for a buffer at all.
The 10uF cap determines how long the leds stay lit when the input signal drops to zero. I accidentally put a 47uF cap there, and it caused the lights to stay on much longer. They would slowly turn off one-by-one over several seconds when the signal was removed. The overall effect is that the meter becomes sort of unresponsive. I've been using 6.8uF or 4.7uF (tantalum) caps in my circuit, and it works fine with those values. (Maybe your 10uF cap is causing the hiss)
I appreciate the insight. I'll do some testing right now.
Okay, I've built another copy of the circuit, except the voltage divider is a 1M trim. I'm testing it stand alone. No buffer or any device is engaged. Here's a video and a couple of pictures. The issue still remains. If you pluck a string and let it ring, the LED eventually dies out along with the signal accompanied by a crackling sound in the amp (clearly audible in the video). If you pluck and mute it fast - nothing happens. Any ideas? :)
https://www.dropbox.com/s/9h8czea8vdt0l56/MVI_0353.AVI
https://www.dropbox.com/s/7dqjykknf9cw83o/IMG_0354.JPG
https://www.dropbox.com/s/pmsb1v83egvf8b2/IMG_0357.JPG
Good detailed pictures, and I can see/hear what you're talking about on the video. That helps.
So just to confirm...
the black electrolytic input cap is 2.2 uF?
the yellow cap is a 10uF tantalum? Is it oriented the right way, with the + side going to pin 7?
I haven't noticed any of mine make that noise. On yours, it's probably happening every time while the first LED dims. You just can't hear it when the strings are quickly muted 'cause it happens so fast.
I'll check mine, and see if there's anything I can do to reproduce the issue. Let you know what I find.
Quote from: waltk on July 22, 2013, 03:32:51 PM
the black electrolytic input cap is 2.2 uF?
the yellow cap is a 10uF tantalum? Is it oriented the right way, with the + side going to pin 7?
I haven't noticed any of mine make that noise. On yours, it's probably happening every time while the first LED dims. You just can't hear it when the strings are quickly muted 'cause it happens so fast.
I'll check mine, and see if there's anything I can do to reproduce the issue. Let you know what I find.
Yeah, it's 2.2 uF. The yellow one is indeed a 10uF tantalum with its positive side facing pin 7 of the chip. True. It crackles as the first LED dims. I took out the capacitor altogether and what happens is a constant crackle. I've also tried a different value of 4.7 uF with the same result. It would be very helpful if you checked how your circuit behaves. :)
Quad, I built another one with everything socketed. I put in components that were as close to yours as I could get, and was unable to cause it to make any sort of noise (even with varying several things). The chip I'm using is a KA2284 - an AN6884 clone. Maybe the particular chip you're using is bad or noise-prone. From the photos, it looks like your layout and build are correct. So I'm stumped.
@quad:
i thought i'd test my 9 led version too..
i stuck it on breadboard with input/output connected together
and your right i did get a little crackle as the last led faded...i had to turn the fader right up to hear it, but it is there....hmmmm...
it also crackles when just triggering the first led too.....hmmmm bugger. :(
@walt can you turn your level right up and try it...to test. cheers :)
Interesting. The chip could be the culprit. I've tried a couple of AN6884's and they all behave the same. I think Rob's using these too. Time to get my hands on one of those KA2284 clones.
yes i'm using an6884's too....hmmmm..
if i get time i'll breadboard another 5 led version, and have a look at it...
Quote@walt can you turn your level right up and try it...to test. cheers
Tried that. Had it cranked up loud enough to cause permanent deafness if I had accidentally hit a string. No detectable noise (at least not more than the minimal hum from expected from the amp).
hmmmmm..... :(
more like "Buzzzzzz..." (from the video) :)
Yeah I noticed the fading out static when I first built this circuit a while ago. Wasn't sure where its coming from but I didnt suspect the IC. I thought possibly it was a ripple across ground while the electro cap drained. And thought isolating ground from my guitar signal and the vu circuit might help.
I built the CP9 comp from tonepad and popped this circuit in with the signal coming from the output jack of the compressor. Overall its fine unless playing really slow long vamped out stuff or at the end of a song letting the last note ring out. I'll try to help get rid of that static ripple as soon as I get a chance.
On a side note, remember those leds start eating up current might wanna run it on its own power supply. I was playing with it and about 4 more pedals on a daisy chain and it caused the psu to give up haha.
^ hmmmm so the ka2284 seems a better choice going by walt's experience of it...unless the smd leds affect it differently somehow ......shame, i bought a few of these ::).
just for reference :
http://www.e-ele.net/DataSheet/AN6884.pdf
http://pdf1.alldatasheet.com/datasheet-pdf/view/37175/SAMSUNG/KA2284.html
Quoteso the ka2284 seems a better choice going by walt's experience of it...unless the smd leds affect it differently somehow
Well, it could be the chip, or it still could be something else (as Mustachio suggested - some kind of ripple from the cap). I tried some different LEDs; full-size ones, and different colors, so I don't think that's it. Maybe it's layout-sensitive (unlikely IME), or something outside the circuit - like pickups or amp.
QuoteOn a side note, remember those leds start eating up current might wanna run it on its own power supply.
On mine, it draws 5 ma with no LEDs on, and 8 ma with all LEDs lit - using a 2.2k resistor. That's pretty doable on battery.
Just based on experience with the 555, which may not apply here, but stick the biggest-ass electrolytic you have from the power pin to ground. Connect it right at the pin, or as close as you can.
My inclination here is that pcb/vero layout is going to be key....the incoming signal ground should be as close to the supply ground point as possible (or battery -ve cable) ....and the guitar signal ground should not share the same an6884's ground return path....it shou dhave its own.
I reckon probably all the LEDs click as they turn on & off (vs just the first LED), but the larger guitar signal will likely mask the click wrt the other LEDs.
What happens when you remove the first LED out of circuit? (I'd imagine the click will go)
I've tried placing a capacitor across power - ground right at the pins. Didn't seem to change anything. When it comes to removing the first LED, the 2nd one becomes the last one to crackle, so only the last LED seems to be making noise.
Still waiting for those chips. If that won't work, I might play with the layout a little bit. In the meantime my Crybaby wah-wah is taking in some serious mojo. :icon_lol: I couldn't find a sole 4uF capacitor. Ridiculous. It sounds alright with all the modifications. A little more wah'wah-y instead of woh-woh.
https://www.dropbox.com/s/ly3hl0y5dfp0od2/IMG_0365.JPG
Hey waltk,
I've got your package. Really appreciate it. :) So far I've tested the SMD board and swapped the chip on my old board. The SMD board crackles in the same way, swapping the chip made the noise less noticeable, but it's still there.
OK. So to summarize, using the KA2284 instead of the AN6884 seemed to help a little in one scenario, and not at all in the other. My own experiments have all been dead quiet. It must be something outside of and/or interacting with the circuit. Something about the guitar pickups or the amp is different for you. It would be nice to know what causes the noise for you and not for me, but it's kind of hard to tell without being able to reproduce it. Oh well - let us know if you discover anything else.
Oh Yeah I forgot to post about this again. After I posted last time in this thread I went down stairs and plugged the pedal back in and tested it.... No click or any audible sounds at all in fact a very dead silent pedal(ibanez cp9 layout from tonepad) .
And I remembered last time I fiddled with it I set the trim pot up a bit higher so the leds where not as responsive as they could be yet still gave me a full reaction when I strummed hard. So there ya go fiddle with that trim pot. I'm sure there could be improvements to how we use the an6884, but overall it works great and is simple and cheap! I'll have to take a look at those other KA chips some time they look neat!
^ cool, so stick with the trimpot then...
or change the divider resistor values...hmmmm....
i'll bread one up when i get time and try it again...cheers jim. ;)
Okay, so far my only solution is not to allow the first LED to go out, so no ripple. Not very satisfying, but at least it doesn't buzz. Oh, and screwing around with the trim pot didn't help much. If you turn it down, the noise is barely audible, but so is the representation of signal on LED's.