Introducing the "One Chip Chorus"!

[merlinb]

I *think* this is based on the updated version. Please check before attempting - it's late - I'm tired.

Wow, you work fast!

Here's a quick sound clip of 'Entropy'. Starting with the depth pot fully dry and then rotating towards wet (pure vibrato), then back again at a slower modulation rate:
w w w.freewebs.com/valvewizard2/SimpleChorus.mp3  (remove spaces and cut and past into browser, otherwise my provider tries to redirect you back here)
The background hum is not the circuit, it's just the shoddy unshielded, crocodile-lead rats nest of a recording setup!

How crucial is it to use a BC337?  Would substitution with a 2N series transistor be possible?

Not at all crucial, any NPN should work.

[frequencycentral]

Well who can sleep through these hot nights? Actually I see a way to get the two rate pot pads closer together, so I'll amend and re-upload later today.

Soundclip sounds good, hiss free, perhaps a little too wobbly? Really, your depth pot is a mix/blend pot - useful though. How about adding a proper depth pot? That way the over-wobble could be tamed to a shimmer. Voltage divider somewhere in between pin 14 and pin 2?

[Govmnt_Lacky]

Interesting... I get the "Page cannot be found" annoyance when I paste the link  

EDIT: Nevermind... it is my work computer. DAMN Firewalls   

[merlinb]

How about adding a proper depth pot? That way the over-wobble could be tamed to a shimmer. Voltage divider somewhere in between pin 14 and pin 2?

Unfortunately that won't work as the oscillator needs to modulate Vref in the first place, or else it won't oscillate! It was really just an exercise in adding to the knowledge base of the PT2399 applications, I wasn't really suggesting it is a full project.

[Earthscum]

Not sure if I'll have it populated soon or not, have a show this weekend, and some stuff to do tonight, but...

[Taylor]

Beautiful board Earthscum. I'm guessing due to the time between posting that layout and now that you made that yourself? I think I recall that you have silk screen equipment so that makes sense. How'd you do the "soldermask"?

[Scruffie]

Not sure if I'll have it populated soon or not, have a show this weekend, and some stuff to do tonight, but...

Wheyy, glad to see my layout being used  let us know if you do get it verified.

I'm not sure if it's the picture though or your soldermask but are some of the tracks underneath the IC touching the pins they're not connected to? I know it was tight but they don't on the layout.

[Earthscum]

@Taylor: I have actually had the image on screen since the day after it was posted. I printed and etched it today. The solder mask is lacquer, printed on the entire board except the pads, same as I do for etching. I used 50/50 dark opaque blue and clear, but just use black for etching block. That's why some of the traces look like they're touching, the ink is just darker in the recesses. I trimmed a couple pad edges that were a bit close to the traces.
 
I have a super compact 'japanese style' layout with pads for trimmer or resistor/pot that I will try and get posted up tomorrow for the heck of it. This one is going into the reserved circuits box in case anyone needs a chorus. The one I laid out is going to be part of a much larger circuit, so I needed the extra room. The layout happens to work out for a stand-alone so figure I'm gonna share, lol.

ETA: Ha! 666th post!

[Earthscum]

Pad between pins 2 and 3 should be connected to only 3. I got a dead chip, I believe, lol. PSO sounded like it was working, though.

Fixed the pad, yep. Burned the chip.

And...

SCRUFFY'S PCB CONFIRMED (as long as you change that pad to not contact Pin 2).

I dig it, for sure. I may have to see if I can cram this in the box with the LA... they both have unique character. This sounds pretty damned great on Bass, BTW. Maybe a little wet, but actually sounds great to me.

[Scruffie]

Pad between pins 2 and 3 should be connected to only 3. I got a dead chip, I believe, lol. PSO sounded like it was working, though.

Fixed the pad, yep. Burned the chip.

And...

SCRUFFY'S PCB CONFIRMED (as long as you change that pad to not contact Pin 2).

I dig it, for sure. I may have to see if I can cram this in the box with the LA... they both have unique character. This sounds pretty damned great on Bass, BTW. Maybe a little wet, but actually sounds great to me.

Ahhh I see, the 100uF, i'll alter that in a day or two and repost.

[anchovie]

SCRUFFY'S PCB CONFIRMED (as long as you change that pad to not contact Pin 2).

I dig it, for sure. I may have to see if I can cram this in the box with the LA... they both have unique character. This sounds pretty damned great on Bass, BTW. Maybe a little wet, but actually sounds great to me.

Hooray! Glad to hear the circuit works for someone who isn't me!

[Scruffie]

Pad between pins 2 and 3 should be connected to only 3. I got a dead chip, I believe, lol. PSO sounded like it was working, though.

Fixed the pad, yep. Burned the chip.

And...

SCRUFFY'S PCB CONFIRMED (as long as you change that pad to not contact Pin 2).

I dig it, for sure. I may have to see if I can cram this in the box with the LA... they both have unique character. This sounds pretty damned great on Bass, BTW. Maybe a little wet, but actually sounds great to me.

Ahhh I see, the 100uF, i'll alter that in a day or two and repost.

Day or two... almost 2 weeks... same thing.

[Yazoo]

I built the one chip chorus and had the same problem as Brymus, the pulsing distortion. I saw the post about variations in the PT2399 chips so I ordered 5 units from China on eBay. They only cost about 50p each. I've just swapped out the chip today and it works fine now. 

[HOTTUBES]

The sound clip sounded great imo !
Does anyone know if or when the Vero pic will be verified ?

[anchovie]

Unless anyone else tries it first, I'll verify it when I finally build mine properly to go in a box (half the breadboard components have been pinched for other things and I've been distracted by lashing together a new tube amp).

[pinkjimiphoton]

hi anchovie,
i built the vero posted....and tried 5 of the 6 pt2399's i have...saving the last one for when...

wellp, there's a problem with the vero. it's weird, it passes signal, and if i mess with the pins and short some of them together, it works for like one sweep. if  hot-swap the chip (i know) it also will work for a split second. i think the lfo is working if i short pins 13 and 14, i hear a sweeping oscillation.. but i can't get it to work like the demo.

i built it straight to the vero, checked for bridges, even dremeled between the strips to be sure...

it's gotta be something obvious, i think...

here's some voltages from the ic socket to ground, going from 1 to 16,
1   4.94           16   2.41
2   2.38           15   2.41
3   0.0             14   2.38
4   0.30           13   2.39
5   2.96           12   2.41
6   2.17           11   2.38
7   1.03           10   2.38
8   1.02           11   2.40

here's a couple crummy phone pix:





can anybody figure out what i got wrong? tried taking measurements without the chip, everything kept dropping...really weird!!!
hoping that someone can figure it out, really wanna make this puppy work!!!!!   

[Pigyboy]

I built the one chip chorus and had the same problem as Brymus, the pulsing distortion. I saw the post about variations in the PT2399 chips so I ordered 5 units from China on eBay. They only cost about 50p each. I've just swapped out the chip today and it works fine now. 

I'm afeared of buying the 50 centers from China - I got a bad batch before. They are a relative fortune to by them from Smallbear but I know they all seem to work. 
Do you have the ebay link?
Chris

[Yazoo]

I don't have the eBay link for the PT2399s from China but the seller name is "goodbuy7888". I've only used one of them so far, the first one out of the tube, and that works fine.

[Pigyboy]

Thanks Yazoo,

I have a good batch from Smallbear here to use up first.

[pinkjimiphoton]

duuuuude....

it was an almost microscopic break in one of the rails!!! 


but,

now it works great!!   



reminds me of my old boss dimension d!   

the vero is now VERIFIED, fwiw!!   

thanks anchovie!!  gotta box it up, will try and post clips this week.