"Little Angel" - Super Simple PT2399 Mini Chorus

[davent]

If you have a drawing program such as Inkscape (free), open the pcb art there, set the background grid for 0.10 inches, scale the board so that the IC pads match the 0.10 inch grid. Not sure if there is a PDF available, someone else did a really nice layout for the Turkey Shootout contest, again not sure whether ther's a PDF.

dave

[aballen]

I got it.  I'm using Gimp.  Opening the image it seems to set it to 72 dpi, I changed that to 200 dpi, and the board prints perfect.  Already etched and drilled. 

I believe I read through most of the thread, and I'm hoping I can get a little more info.

• Is the BOM in the "birthday edition" on page 33 of the thread the latest?  It look like it is, just wanna be sure.
  
• Can I get ADT by just turning down the speed and depth, with the latest BOM?
  
• And lastly, has anyone tried to put 4-5 pots in the 1590a, because I want to add the delay and mix pots back in.  I'm sure I can get 4 in a 1590a... maybe even level, though if it puts out unity gain, then I don't have much need for the level pot.
  

Thanks for the great project, I'm so hooked on 1590a builds lately.....  Now if anyone could just come up with a good 1590a verb.

[gcme93]

Hi all,

Firstly, big props to Rick for this, thank you so much for putting the time in and giving us all something fun to make like this!

Here's the question:

http://www.sabrotone.com/wp-content/uploads/2011/04/LittleAngelRev1.gif

I'm following Sabro's great Vero layout, but haven't got a 330K resistor for R7. Is this a pretty crucial potential divider or something? Or would I be okay to sub in a 220K or 470K (which?). I honestly don't know enough about the circuit on this one :s

EDIT:

SOLVED IT MYSELF! This resistor happens to go straight over an extra line of track I left in the vero board. Hence easy enough to add two resistors (100K + 220K) to make a very close 320K.

Sorry for the unnecessary message, this is now just a "watch this space for another Little Angel project" message


Gut shots and enclosure photos to follow shortly

George

[gcme93]

Finished!







Ugly as anything, but it is my first pedal, and I'm amazed that it works after only a little debugging. All the ground and live wires are different colours, the board has a few crazy diagonals on it, but ultimately it works perfectly!


Problems along the way:

1. Enclosure too small, so everything is insulated with plastic and stickers :s

2. Didn't have the right resistor at one point, made it with two in series, but made a complete mess of the board while doing so.

3. Made a solder bridge across pins 13 & 14 instead of pins 3 & 4 (confused when looking at vero layout upside down I guess)


Most useful things

1. Nick D's voltages: (very similar to mine though mine are all very slightly higher)

                                                      IC 1          1) varition from 1.4 - 7.4 ( lo-speed ) to 2.5 - 3.5 ( hi-speed )     
                                                                      2) 4.87 V
                                                                      3)  4.77 V
                                                                      4)   0.00 V
                                                                      5)  varying 2.5 - 3.5 V
                                                                      6)       "     2.5 - 3.5 V
                                                                       7)      "     1.4 - 7.8 V
                                                                      8 )  8.56 V (normal output of my PSU ) 
                                                                       

                                                      IC2             1) 5.02 V
                                                                        2) 2.5 slight wobble
                                                                        3) 0V
                                                                        4) 0 V
                                                                        5)  2.22 - 2.5 V   (didn,t spot the small variation before )
                                                                        6)  0.75 V
                                                                        7)0.66 V
                                                                        8 )  0.66 V
                                                                         9 - 16) all as pin 2 , i.e.minor variation around 2.5 V


2. Harald's vero layout and website: http://www.sabrotone.com/?p=332
     - tons of useful guides/ advice/ links etc. on that website

3. A new half decent soldering iron

Huge thanks to Rick for this, awesome sounding pedal. I'll upload recordings tomorrow if I have time.

[arma61]

Hi m8s


got a couple of questions/issue with this little gem!!

I'm talking about the very first version in this thread, build a couple of them all work good, nice chorus effects and controls act as they should, voltages look good.

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%....

Second issue, I've tried to make it in a 1590A encl with light emitting border, using an ultrabright Blue LED hooked between OpAmp Pin 1 and gnd, to flash in time with the Rate, in this case I almost completely loose the chorus effect until I increase the Led resistor to almost 100k, in this case the LED lights up just a bit! so no use of it...
Any solution to this ?

Thanks as usual for help m8s!!

Ciao

[mremic01]

I finally got around to putting together a Little Angel, the Birthday Edition. Stock it's ok, but a little dissapointing. The speed pot is only useful through the second half of it's rotation, and the depth pot through the very end. I think I'm going to switch to a b100k on the depth pot. Have you guys had the same issue with the speed pot? I might try a b50k instead of 100k. Overall, even with the depth dimed, it's still pretty subtle compared to a Small Clone or CE-2. With my CE-2, I can dial back the depth if I need to, but with the LA I can't dial in anymore, and some of the clips posted sound quite a bit more chorus'd than what I'm getting with any PT2399. After skimming through the entire thread, it sounds like some of you guys have that issue and it's not nearly as lush as the clip on page 33.

[gcme93]

I finally got around to putting together a Little Angel, the Birthday Edition. Stock it's ok, but a little dissapointing. The speed pot is only useful through the second half of it's rotation, and the depth pot through the very end. I think I'm going to switch to a b100k on the depth pot. Have you guys had the same issue with the speed pot? I might try a b50k instead of 100k. Overall, even with the depth dimed, it's still pretty subtle compared to a Small Clone or CE-2. With my CE-2, I can dial back the depth if I need to, but with the LA I can't dial in anymore, and some of the clips posted sound quite a bit more chorus'd than what I'm getting with any PT2399. After skimming through the entire thread, it sounds like some of you guys have that issue and it's not nearly as lush as the clip on page 33.

Hi mremic,

I'm gutted I couldn't record a sound clip before giving my LA to my cousin (21st present), but I had some pretty deep chorusing all the way up, and pretty usable speed control across the whole range (0 to 4 pretty slow, 6-8 useful and 9-10 a bit intense).

Perhaps your speed control is indicative of something wrong? I'm sure you've checked your voltages against the ones Nick D made? (I repeated them a few posts ago)

As for the depth control, there's two schools of thought on it:

1. No one's LA has depth that does much before about 50% but it having the effect on below this does make your tone warmer, and slightly doubled (not volume wise, just like to guitars playing at once) rather than chorusy

2. Those that don't like that so much have done something along the lines of 250K in series before lug one of a 250K pot: This gives you the latter stages of the depth control, but makes your total sweep the equivalent of anyone else's 50% -> 100%


Keep us updated!

[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!!

Still waiting a suggestion for my 2nd issue 

Thx

Ciao

[kornerrr]

Hi, can anybody send me correct voltages of ICs for little angel birthday edition?

[garcho]

From Rick a few pages back:

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

[kornerrr]

These voltages that you posted are from little angel basic edition, i thought birthday edition has little different voltages, im beginner ,so i dont know much about electricity

i have changed 470K to 100K, my problem is i have very subtle/no chorus.

My voltages :

PT2399

1:  4.92
2:  2.45
3:  0
4:  0
5:  0.21
6:  0.86
7:  1.08
8:  1.21
9 through to 16: 2.46


NE5532

1:  1.47 to 5.3
2:  2.73
3:  2.45-2.9
4:  0v
5:  3.14
6.  3.95
7:  4.35
8:  8.50

I will be glad for any advice, thanks.

[MrStab]

Edit: ignore this post, got it working. was either a tiny solder bridge or a slightly-loose cap. thanks anyway!  time to jam
hi,

my signal seems to split but not oscillate. if that makes sense. accidentally moving the floating bridge on a guitar seems to compensate for what the Little Angel isn't doing.
whilst debugging opamp A earlier, there must've been a short between vertical resistors or something, as i heard the LFO clicking (i think), but now no sign of it at all. i've swapped out PT2399 for a known working chip (and the one i removed works in a different circuit), so it doesn't seem to be that.

voltages seem okay except for the 2nd half of the TL072 i'm using - which, correct me if i'm wrong, is part of the LFO, no...? the first 4 pins function fine, but i'm picking up 2.9v on pin 5, 1.35 on 6, and up to 7.6 on pin 7. pin 8 is also fine. a lot of seemingly-random fluctuation, too, with no obvious bad joints.

any idea where i should be looking? maybe that now-elusive clicking sound from earlier could offer a clue.

 cheers!

[kurtlives]

What's the latest greatest version of this pedal? Schematic?

[garcho]

diysb wiki. I recommend breadboarding this and messing with it to taste, if you play mostly one guitar through one amp. Lots of fun mods, too.

[Focalized]

Built this on strip board. Really like it. Thanks for the design to who is deserving.

[kurtlives]

diysb wiki. I recommend breadboarding this and messing with it to taste, if you play mostly one guitar through one amp. Lots of fun mods, too.

Cool, thanks!

What's this "Birthday Edition"?

[Vikt0r]

This is my build. Based on the "birthday edition".
Mods include a mix/blend pot, 100K for depth (along with a 10K instead of 33K at pin 2).

[Renegadrian]

Quickly built my second LA those last 2 days...Great effect!
Built using standard version, vero by Sabro (it should be at page 19 if I remember correctly...) - I went straight with the 100r resistor, PT works fine...Used 2 100k-B pots. Connected a resistor (2.2k) and a LED to grd at pin 7 of the 072, nice addition! The speed LED.

[joshprdelac]

Hi , i need help with my LA build.   I have problem with depth of chorus, pedal is working but chorus is subtle and is hearable only if i turn speed pot to more vibrato sound.
here are ricks voltages :
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)

- i have on Pin5 only 0.30 to 0.90V instead of 2.75V ,the rest of pins are similar, please can somebody help me?

[Vikt0r]

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.