Introducing the "One Chip Chorus"!

[deadastronaut]

cool.   when i breaded this and the la chorus, i found this to have more depth....might have to re-bread this again...cheers.

[bluebunny]

... (some resistors standing up, one diagonal resistor!, etc.)...

Couldn't C11 move one snap to the left and let R10 go straight down? I don't see any break under C11 so it should be ok, shouldn't it?

And surely R4 and R5 can be stretched another hole and be flattened.

Hmmm...  yep, you could be right!  That resistor (R10) was the last thing on the board and it was very late...      R4 could certainly stretch a hole, but R5 is hampered by those huge greenies!  But there would be room with something a little less enormous.  Good spot!

[Perrow]

Good spot!

Well, building in diylc is my best game, I've probably spent more time looking for ways to improve designs in that program than I've spent playing guitar 

[bancika]

and I've spent more time making it than playing the guitar

[bluebunny]

Well, building in diylc is my best game, I've probably spent more time looking for ways to improve designs in that program than I've spent playing guitar 

and I've spent more time making it than playing the guitar

Anyone would think this DIY pedal building lark is a bit of an addiction... 

[deadastronaut]

and I've spent more time making it than playing the guitar

thank @#$% for that!....its a great prog!.

[Puguglybonehead]

OK, trying to understand the PT2399 here. If I want to make this with a wet signal only, do I disconnect pin 15?

[anchovie]

Remove the 10k that comes from pin 15 to the output. Or put a SPST switch in series with it if you want switchable chorus/vibrato modes.

[mwynwood]

Remove the 10k that comes from pin 15 to the output. Or put a SPST switch in series with it if you want switchable chorus/vibrato modes.

Is that R13?

[anchovie]

R11 on the vero. I notice that I put 10K for R13 on the layout but 100K on the schematic (output pulldown resistor) - I think that would cause a difference in output volume.

With inconsistent PT2399s and my careless scribbling/typing, this has been a bundle of fun for everyone! 

[Puguglybonehead]

Thanks! I'll give it a try. Very cool project! Thanks so much for sharing.

[bluebunny]

@marc: any problems with pt2399 lockup...?

Nope, not so far...

I think I spoke too soon...  three months later... 

Having finally stuffed this into a box, I've just had two PT2399s wig out on me: no chorussing to speak of, and they were getting pretty damn hot!  So I guess they were indeed locking up...

Anyway, swapped out for a third one, this time working OK.  But now I'm getting some pulsed noise in the background.  Anything less than 4 o'clock isn't intrusive (if I'm playing), but maxed out, it's a rhythmic resonant squeak - like someone periodically hiking the resonance control on a synth.  I just read through the whole thread looking for clues, but I think I need to be mentally sober to spot the answer (if there is one)...

BTW, is a locked-out PT2399 forevermore toast, or can it be re-homed in something with one of the anti-lock circuits?

[pinkjimiphoton]

that noise is either a dead 2399, or more likely a damaged regulator. try replacing the 7809 and see if it goes away.

even then if you have a working 2399, it may just well crap out on you later...that happened to me.

i built rick holt's little angel, same issues even with the bug fixes, and i went thru 20 different 2399's from three different vendors....tayda, ebay (polida) and small bear.

i think it's just a crappy chip.

it seems from my experience, that once they lock up or overheat, they may still work, but they'll never work right.
at least one of the ones i have is damaged to the point of not passing audio.

the damaged ones tho, i guess you COULD use the opamps in them to make fuzzes or something.

[bluebunny]

Thanks for this, Jimi.  I'll check the regulator, although it was putting out a solid 5V as expected.  BTW, I also built Rick's LA ("birthday edition", with the anti-lock) and it worked just fine.  Hmmm... some you win...

the damaged ones tho, i guess you COULD use the opamps in them to make fuzzes or something.

LOL!   

[pinkjimiphoton]

i found that some of my 7805's, even tho they seemed to be working correctly, made noise worse in this and rick's little angel.

good luck mate!

[bluebunny]

i found that some of my 7805's, even tho they seemed to be working correctly, made noise worse in this and rick's little angel.

good luck mate!

Another good tip (I shall fire up my scope and take a look) - thanks Jimi.

[rhcp_schipper]

Hello You guys,

I've build the one chip chorus with the layout of Scruffie , and there was a little volume drop. In this topic I read that chancing the 10 Uf cap at pin2 to 100 Uf and chancing the 680k resistor to 330 would give nicer chorus an more output. This is true but now the chorus has gone from volume drop to a little to much volume(a bit of a volume boost). Is there a way to decrease the volume a bit? 

I'm now using the voltage divider pot(100k), but is there another way to do this? Don't want to ad another pot.

Thanks!

[pinkjimiphoton]

try 470 

[oldschoolanalog]

Install a trimpot. Season to taste.

[pinkjimiphoton]

dave! good call bro