"Little Angel" - Super Simple PT2399 Mini Chorus

[frequencycentral]

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[Perrow]

@ stringline: Debugging sticky thread

@ Madness: Debugging sticky thread

Cool, this thread does echo effects now 

[pinkjimiphoton]

hey rick,
i think i have a new weirdness to report...no, i haven't read thru EVERY post of the 40 some odd pages... but i did skim thru..

i built IVIark's vero layout, for version 4 with the warble switch and the chorus/vib switch.

can't get the puppy to work, right? so i breeze thru the thread, and check for solder joint issues, etc...can't find anything. jeweler's loupe, etc etc...

then i noticed that if i disconnect the ground that goes to the emitter of the 3904, and reconnect it a couple times, eventually the whole effect fires right up, and suddenly works great.

as soon as i power down, same thing exactly happens...dead. it will pass signal if the chorus switch is in chorus mode, but only appears to pass dry signal..switch to vib mode, and it's dead.

mess with the ground, 3, 4...maybe 5 times, and suddenly there's the warble again. it is WEIRD.

i've tried 12 different 2399's, a couple plain don't work at all, some sound great, some sound mediocre. i've got the 3 best sounding ones put aside, and the best sounding in the circuit.

but the lockup thing seems to be happening, and i've checked it over and over...why the heck would i have to disconnect the ground over and over? any ideas?

could it be because i don't have it boxed yet or something?

i could really use a clue here... anybody got one?

gonna keep messing with it..thanks in advance, if anyone can figure it out!!!

[pinkjimiphoton]

wellp, i boxed it cuz i like it so much, but it's got issues. i tried messing with the 3904 as i read in the thread, changed the 68k to 220k....that seemed to help a little bit.
tried replacing the 47r resistor from the collector with an led from the emitter...couldn't get it to do anything that way, so put it back.

if i plug in the input jack a couple times, it will catch and work fine until it's powered down, but then if i plug it in again, i gotta plug it in several times again.

really freakin' weird...any other ideas anyone can point me at? thinking about adding another switch so i can ground/unground the ground connection...that seems to be the issue, but i'm too newb or too stupid to figure it out.

once it's working, it's absolutely astounding...beautiful toney cct, i love the warble control...it makes it sound a lot like my old clone theory sorta..

lush. sounds good even into fuzz!!

[frequencycentral]

Hey Jim, did you catch any errors on the IVIark layout? I seem to remember some bug fixes on his forum.

[pinkjimiphoton]

hi rick,
i went thru the whole thread at Mark's forum (alot easier than this one, a lot shorter! )

i saw the bugs in the first layout he posted, but i built the full-gospel one with the anti-lock fix, as well as the chor/vib and wobble/warble switches.

i DID change the 68k resistor to 220k as merlin suggested, and tried lifting one side of the 47r resistor and replacing with an led as suggested by merlin, but then couldn't get it to work at all.

it's REALLY weird... plug it in, dead soldier unless in chorus mode, where you can hear the dry signal and it being buffered. all the voltages seem to be in the ballpark of everything i've looked at.

i tried 12 different 2399's, one was bad, all the rest worked, tho some sounded better than others. mess with the ground 4-5 times and it comes on. every time. sounds spectacular!! once it's working, you can kick the effect in or out with impunity. i left it on all nite to see if it would mess up, worked fine this morning.

sure enough, disconnect it, reconnect it and power up, dead soldier. unplug the input jack 4-5 times, and sure enough, it works again. it's almost like ya have to "trick" the chip into working...

too much mojo for the kid to figure out here!!

every thing i've tried with pt2399's seems to have some kind of issue, which is a drag, cuz when they work they sound great.

[pinkjimiphoton]

oh, almost forgot...

one thing i did find? if the effect is noisy, change out the 7805....on mine, some of the voltage regulators in my junk box made obscene amounts of noise, even ones that "seemed" to be working well... the bad ones caused hiss, weird intermittent whooshing noises, and in some cases metronome like ticking.

a good 7805 (read: brand new) fixed that.

so if anyone is having issues with noise and using junkdrawer recycles or pulls,  try a fresh one.

peace!

[SeicheNZ]

FIY, the new Mad Professor Electric Blue Chorus employs a PT2399 as well.

[TheVice]

Hello fellows. My first post here. Been lurkig for a while, though 

I've built this one, and my lord, is it sweet sounding. I've only got two problems with it:

1: the 3pdt switch pop! All the methods that I know have failed so far. I've added a "soft start" RC network for the LED, and pulldown resistors. I assume that's the role of R19, right? Well i've tried switching it for a 10M one, to no avail. Tried adding extra pulldown resistors to the input and otput. So far, I only built boosters / overdrives / distortions / active EQs, and tremoloes. Always tackled the pop problem. This one made me give up.
Ah, if it makes any difference, I did some mods to the original schematics: added a blend pot instead of R18, a delay pot instead of R1, decreased R13 to some.. 1k, I think, to get a deeper depth. A word of advice, anyone?

2: Some hiss showed up with the delay at max (50k pot), anyone tried this and did get rid of he hiss?


cheers.

[pinkjimiphoton]

did you try a different 2399? some of them seem to amplify switching transients.

they really seem to have a crazy wide set of tolerances.

perhaps (newb alert) a big ass cap, say, .22 or so, in parallel with the pulldown resistor will help?

[TheVice]

I did try 3 other. No difference between them that I could spot. I also did try your cap-across-the-pulldown-resistor mod, although I had no idea of what this could be aimed at achieving. All i (think) I did was to direct a considerable part of the signal to ground.


@pinkjimiphoton:

try to add a electrolytic cap (200uf-2200uf), across the input terminal of the 7805 and ground. You might also try two 0.1 caps from the input and output terminals to ground (the central one). I found one day that while 7809s and 7812s can 90% times be plugged in without any extra caps, the 7805s tend to have issues, although the output voltage looks just fine. Hope this will work for you.

[pinkjimiphoton]

diggit. i just remember using big caps in a footswitch years ago that was switching wall voltage in a homebrew leslie controller i had built.

thanks for the headsup on the 05's, i'll remember it if i run into a problem.

[TheVice]

Right, it was you writing about the 05 as well. Thought I was answering to someone else's post. Long day,  it was 

[haveyouseenhim]

First post here so be gentle... I made a little angel from this layout :  http://freestompboxes.org/viewtopic.php?f=13&t=10276

I'm losing my mind over this thing. I know i built everything right because I've gone through with a fine toothed comb many times looking for mistakes, but when i power it up its like an overdrive/distortion chorus.
Does anyone have any ideas what this could be?

I haven't read every post because its 40 something pages, but what I've read hasn't mentioned anything about overdrive/distortion being a problem.
if someone could help that would be awesome.

[haveyouseenhim]

didn't realize i couldn't link to fsb... lets give this another try

[frequencycentral]

I know i built everything right because I've gone through with a fine toothed comb many times looking for mistakes, but when i power it up its like an overdrive/distortion chorus.

Your first step is to realise that you did something wrong. 

Got voltages for us?

[haveyouseenhim]

pt2399:
1  5
2  2.45
3  0
4  0
5  2.16
6  .66
7  .82
8  .84
pins 9 - 16 are 2.45
 5532:
1 through 3 fluctuate
1  1.3 to 0
2  3 to 2
3  2.5
4  0
5  4.76
6 4.36
7  7.44
8  8.45

i was expecting that answer... i felt confident that i followed it as it shows. but apparently i goofed
any help would be greatly appreciated.

[Craiz]

Built it for a friend the other day. Absolutely gorgeous sounding....gonna have to make one for myself now (:

[haveyouseenhim]

  Please help me Rick I really want this to work.

[frequencycentral]

Your voltages:

pt2399:
1  5
2  2.45
3  0
4  0
5  2.16
6  .66
7  .82
8  .84
pins 9 - 16 are 2.45

 5532:
1 through 3 fluctuate
1  1.3 to 0
2  3 to 2
3  2.5
4  0
5  4.76
6 4.36
7  7.44
8  8.45

My voltages:

Here are voltages just taken from my Little Angel, which sounds the same as the breadboarded version I did you soundclips on. Speed at 3 o'clock, Depth at 12 o'clock:

PT2399

1:  5
2:  2.38 to 2.42
3:  0
4:  0
5:  2.75
6:  0.61
7:  0.88
8:  0.88
9 through to 16:  2.41 (slight movement)


NE5532

1:  0.13 to 4.9
2:  2.9 to 3.2
3:  2.7 to 3.1
4:  0v
5:  4.79
6.  4.9
7:  5.14
8:  9

So it seems that your voltage at 5532 pin 7 is really high. Which would suggest either a solder bridge (migh be microscopic - scrape between the pins), or an error in the value of R7 or R15.