"Little Angel" - Super Simple PT2399 Mini Chorus

[GodSaveMetal]

Hi!
To increase depth you may try to decrease the value of the resistor that goes to pin 2. With 10 kOhm you'll get deeper effect, i ended up
with 2.2K, although this way the depth pot affects also the speed rate of the LFO (due to LFO load impedance variation). With 33k the effect
didn't have enough depth (as for my taste).
Also you may try checking pin 5 with an oscilloscope - this is the internal clock generator output, but provided your effect works - the clock is present.

Hi, my friend please more details of your mix/blend pot; thanks a lot it is a metal chorus ehhh!!!! great!!!

[Vikt0r]

Hi, my friend please more details of your mix/blend pot; thanks a lot it is a metal chorus ehhh!!!! great!!!

Not sure what detail do you mean..? It's a dry/wet mixing pot option. A 20K linear pot replaces R18 and R20 (according to "birthday edition" at page 33). In order to get a junction,
i moved C15 to the place of R18, C12 instead of R20. The pot is soldered to where originally C12 and C15 should have been. Watch the PCB photo - should be clear.

[psychedelicfish]

I noticed when I was playing around with a delay on the breadboard that a capacitor from pin 5 to ground made the delay time shorter, I'm guessing it did this by increasing clock frequency... I wonder if this could be used in a chorus/flanger to get a really short delay time?

[Vikt0r]

I noticed when I was playing around with a delay on the breadboard that a capacitor from pin 5 to ground made the delay time shorter, I'm guessing it did this by increasing clock frequency... I wonder if this could be used in a chorus/flanger to get a really short delay time?

Interesting observation. Need to check this with a scope. Will see how much this is true, considering this is the clock output and the frequency should not become affected in theory.

[Paul Marossy]

First issue, cannot get rid of the hiss, I've red the whole a thread couple of time, and applied almost all the suggestions found, probably some of the Anniversary version too..  (and probably understood 1% of it! ) The only one that worked greatly is the 0.047uF between out and gnd no hiss anymore, though there's a significant drop in signal, something like 20%. Other caps values don't produce drop in signal but don't cancel the hiss.
I've tried to recover a little bit of signal decreasing the 10k res at the opamp output, no way.

So what are the right resistors, if any, I can change to recover this 20%....

Ciao

ok, just to report I totally got rid of the hiss with a 3n3 cap between pin 5 and gnd, no signal loss!!

That's a 0.0033uF cap, right? Curious... that's the "clock output" pin. I wonder why that works....

[arma61]

First issue, cannot get rid of the hiss, I've red the whole a thread couple of time, and applied almost all the suggestions found, probably some of the Anniversary version too..  (and probably understood 1% of it! ) The only one that worked greatly is the 0.047uF between out and gnd no hiss anymore, though there's a significant drop in signal, something like 20%. Other caps values don't produce drop in signal but don't cancel the hiss.
I've tried to recover a little bit of signal decreasing the 10k res at the opamp output, no way.

So what are the right resistors, if any, I can change to recover this 20%....

Ciao

ok, just to report I totally got rid of the hiss with a 3n3 cap between pin 5 and gnd, no signal loss!!

That's a 0.0033uF cap, right? Curious... that's the "clock output" pin. I wonder why that works....

I wonder too Paul, but it worked on that one, I have build other one with a little bit less hiss than that one (though still present) , and that 3n3 caps does almost nothing.... don't know..

[Paul Marossy]

First issue, cannot get rid of the hiss, I've red the whole a thread couple of time, and applied almost all the suggestions found, probably some of the Anniversary version too..  (and probably understood 1% of it! ) The only one that worked greatly is the 0.047uF between out and gnd no hiss anymore, though there's a significant drop in signal, something like 20%. Other caps values don't produce drop in signal but don't cancel the hiss.
I've tried to recover a little bit of signal decreasing the 10k res at the opamp output, no way.

So what are the right resistors, if any, I can change to recover this 20%....

Ciao

ok, just to report I totally got rid of the hiss with a 3n3 cap between pin 5 and gnd, no signal loss!!

That's a 0.0033uF cap, right? Curious... that's the "clock output" pin. I wonder why that works....

I wonder too Paul, but it worked on that one, I have build other one with a little bit less hiss than that one (though still present) , and that 3n3 caps does almost nothing.... don't know..

Weird.... 

[Obier]

Has anyone found trustworthy filtering for the PT2399?
I read a lot in this topic, but there are always new problems.

[garcho]

Has anyone found trustworthy filtering for the PT2399?

It's a chip made for mass fabbed karaoke machines and what-have-you, don't expect to find a solution...

What do you mean by 'trustworthy'?

[mth5044]

Yes - a MAX7401. Check out rring's delay on this forum and his site, circuit salad.

[pinkjimiphoton]

found this in my ancient aol email account,
it MAY be a cure for the latchup issue... i haven't tried it yet, but figured i'd post it anyways.
fwiw, none of the other "fixes" have seemed to work for me.

anyways, from one of the gents from  bob keeley's site

Subject: Re:_Jimi_Pocius_Dot_Com

Hey Pinkster,

We were doing some searching for the PT2399 latch-up issues and found your problems on the tagboardeffects website  and we had the same problem as you with the latching up everytime we powered it on and only after unplugging and waiting to plug it back in did it start working again.... We may have found a fix which is a 0.01uF capacitor across pins 2 and 3 of the PT2399. Worked for us anyways.

Let me know if this fixes your problem!!

Craighton Hale

Keeley Electronics, Inc.
www.robertkeeley.com
1733 S. Fretz Ave. Suite C
Edmond, Oklahoma 73013
405-341-2025

[garcho]

i wonder if that would affect the modulation? most PT2399 circuits manipulate pin 6 and have pins 2 and 3 shunted to ground, pin 2 via 47uF.

@Jimi - for what it's worth, my PT2399 builds from the last year or so, including a modded Little Angel, haven't latched up once... yet. Probably will at the worst moment possible.  

We were doing some searching for the PT2399 latch-up issues

If I payed 200 bucks for a chorus pedal, I'd be a little peeved if I saw a PT2399 in there. Just sayin'.

[pinkjimiphoton]

i've had issues with every single 2399 circuit i've tried. some work.... the guitarpcb.com d'lay does...
but the one chip i've never got to work, and rick's little angel only seems to work when it wants to.
my rebote just plain DIED when i tried playing with starving it...
you can get some cool delay modulation by starving the 2399, but it has to be starved AFTER the 7805,  if ya use a normal kind of sag, it smokes the regulator.

i'm going right now to dig out my little angel build, and try the keeley fix. if it works, i'll post immediately gary

[DEVASTATOR]

Fack ! I really don't understand how to connect pots ! Maybe somebody can help me ? 

[Havaden]

Hi everyone, i just made the little angel with the 1590a layout. But it won't work.
I have no understanding of the PT2399 whatsoever, but i think it might be "locked"? Whatever that means?

So when i use it with no power to the circuit, the sound is weak and noisy.
When i plug in the battery, the sound gets to about the same level as without any effects and it has no noise, but no chorus either.
None of the components gets hot and i can't see anything wrong with the circuitboard. No solder bridges, nothing.

there is just no chorus, thats it.

I do have the 100R resistor, and i did read something about having trubles with it. But if that is the case, what should i replace it with?


By the way, this is the voltage readings of the PT2399:
1- 5V
2- 2,43V
3- 0v
4- 0v
5- 5v
6- 0,69v
7- 0v
8- 0v
9- 3,94v
10-16- 2,43v

[Havaden]

Nevermind, i don't know where they was, but there was some small bridges from my badly etched circuitboard.
I just made cuts between every lead, and it worked

[pulsewidthmod]

I'm using the layout on page 8 and audio passes through but no effect. I've looked through this thread and I'm stumped. Here's my readings:


PT2399:
5.04
.83
0
0
.42
1.94
0
.74
2.52
2.34
1.16
2.52
.34
2.5
2.52
.34

TL072:
1.41
.09
.09
0
.06
5.05
9.55

Here's a photo of my build, I've made sure that all my soldering is good.

[toplak666]

I'm using the layout on page 8 and audio passes through but no effect. I've looked through this thread and I'm stumped. Here's my readings:


PT2399:
5.04
.83
0
0
.42
1.94
0
.74
2.52
2.34
1.16
2.52
.34
2.5
2.52
.34

TL072:
1.41
.09
.09
0
.06
5.05
9.55

Here's a photo of my build, I've made sure that all my soldering is good.

And just as I was thinking that I'm the only one with this problem, the first post I see is from someone who has the exact same problem... Mine was working for a while, then after bumped the volume knob to 100% from a high gain distortion pedal I had in front of this one it stopped working. Signal passes through when it has power but there's no effect. Tried replacing both ICs for new ones with no luck. I don't know what else could be causing this... I checked for solder bridges a bunch of times already but still havent found any. Any help would be grately opreciated!

EDIT: I found this if it helps: http://puu.sh/7lolg.png

[deadastronaut]

yep the pt2399 likes to see at least 1k on pin 6.


or it will be prone to lock up...when powering on/off...

[mth5044]

This has to have been mentioned already, but check out figure 4 and associated text on the Elliot Sound Products page for this PT2399 delay findings. Might help with the lock up.

http://sound.westhost.com/project26a.htm