Super simple LM386 is super ripply now and then...

[ExpAnonColin]

It's an older design brought back... it was ripply back then, but with the addition of the .047uf cap at the input and the 100uf cap at the output, it's not as bad.  I've tried using 1n914 diodes at the output to try to reduce ripple as well as large cap values to ground...  I'm not getting much.  I want to use the LM386 because it works pretty decent for single notes, but chords ripple a lot.  Any suggestions?  It doesn't have to be great, I just want it to flash less when chording.

-Colin

[Tim Escobedo]

I'm kinda surprised the single LED blinks at all.

The "ripple" isn't really ripple in the rectified-signal sense, which would be in the audio range and impossible to see. I think this may be a result of different notes pulsing against each other, kinda like when you play two notes slightly out of tune. That effect can be made visible in a audio driven LED.

One simple thing that might help is another LED in reverse parallel with the one already there.

Is that output 100uF cap oriented correctly? The + should go to pin 5, not ground.

I'm also thinking a volume pot on the input might help. Running full blast like it is introduces distortion which may exaggerate the pulsing effect.

[David]

Colin:

Are you trying to make a LFO out of that poor 386?

[ExpAnonColin]

All I'm doing here is using the amplified signal as a CV to control the brightness of an LED.  No LFOs...  just a pretty basic idea.  

Tim, it definitely is the guitar being out of tune... but I can't figure out a way to make it clean.  It makes sense that if I have two close frequencies which are creating beats that the LED would pulse, but I want a way to smooth over the gaps created by superposition.  I'll try the LED in reverse like that...

In terms of the cap, I was thinking the same thing, but it's funny because it really does make a difference when wired like this... when wired the other way the cap just slowly fudders out, instead of helping to smooth it.

I wire it on "full blast" because otherwise the signal isn't quite strong enough to get the LED to glow as much as I want to when strumming hard.

-Colin

[Ansil]

i didnt' use a output cap at all.  and just stuck the diode in there and never had a problem with it.  great sounding fuzz too.

[ExpAnonColin]

Where did you stick the diode?  What was it, a schottky?
-Colin

[Ansil]

Where did you stick the diode?  What was it, a schottky?
-Colin

5mm green led.  it was wired just like your schematic but just bridge 1 and 8 and remove all the capacitors in your circuit. i will draw it.

started out as this.



went to this.


and later this.


and now i dont' even reckognize it lol..
alot of people said it wouldn't work but once i found the correct version of the chip and stopped getting bad ones i haven't had any problems

[ExpAnonColin]

I actually made a envelope follower circuit a lot like this before, so I'm sure our designs have overlapped here and there.  It does work!  but it ripples.  I will try removing that cap at the top and hardwiring it and whatnot.

-Colin