I wondered if it would be possible to make a chorus effect using a PT2399 and no external op-amps and the answer is yes! Instead of using the internal amplifier intended for the output mixer, I've given it a new role in a phase shift oscillator. I originally intended to use the LFO output to modulate delay time, but the nice surprise was that there was no need - the oscillator uses the chip's Vref pin (famously exploited by frequencycentral in the Little Angel as a place to inject modulation) as its ground point and, just by being there, it makes the PT2399 wobble.
The LFO is in no way symmetrical, which I think gives this One Chip Chorus a nice character. The single knob has a subtle effect on both rate and depth - be aware that the LFO needs a little bit of settling time when adjusting to a new setting. R8, R9 and the pot value set the range of the control - with R8 too small I found that a pretty awful pulsing distortion was introduced in time with the LFO. Increasing R9 (or removing it completely) gives a greater downward range but LFO settling times when going from one extreme to the other became quite big. YMMV - we know that there are variances in PT2399s out there, especially in non-datasheet applications!
Schematic:
(http://i56.tinypic.com/ddhwxt.jpg)
(Edit: There should be a 10uF cap between the junction of the 10K mixer resistors and the junction of the 100K and output)
Unverified vero layout (haven't taken it off the breadboard yet!):
(http://i55.tinypic.com/oaam41.gif)
(Edit: C13 on the vero layout is 10uF)
Sound sample: http://www.supload.com/listen?s=BNs8kw (http://www.supload.com/listen?s=BNs8kw)
Beautiful!!
What are the range of sounds like?
Absolutely loved the sound clip.
I'm also interested in the range of the "lushness"
Also, a pcb layout would be nice! I guess I better get crackin' ::)
Very cool! One-chip anything is what's up in my book.
It's been a while since I looked at the PT2399 pinout, but as I read it, the two 10ks are the mixing resistors for clean (right resistor) and delayed (left resistor), is that correct? So vibrato could be coaxed out of this by switching out the right 10k.
Awesome, I really have been meaning to order some PT2399's because of all the awesome simple projects everyone is coming up with. Now if we can just convince my wife to let me make a parts order!
Brilliant and beautiful! Nice work. The sound clip reminds me of a small DOD chorus that I loved, but pulled from my board because of ... I can't remember why. But this is great.
Amazing!
I like it! :icon_cool:
Sounds really nice, and it's great that it is built with common parts. I would love to hear a demo with a full range of control and the bypassed sound.
Love it! I can imagine it ..... NKC@ :D .... a no-knob chorus@ :D into a 1590A.... (setting as per the demo clip, love that sound!)
Thanks for sharing
Quote from: tiges_ tendres on July 26, 2011, 03:49:21 PM
What are the range of sounds like?
Not a huge range but all nice! It doesn't get wild and warbly. I'd be interested to see how others get on with playing with the R8/R9/pot values, seeing as some people had to tweak a few parts in the Noise Ensemble owing to chip variances.
Quote from: Taylor on July 26, 2011, 03:59:51 PM
It's been a while since I looked at the PT2399 pinout, but as I read it, the two 10ks are the mixing resistors for clean (right resistor) and delayed (left resistor), is that correct? So vibrato could be coaxed out of this by switching out the right 10k.
Correct - I used a passive mixer to free up the op-amp for the oscillator. Vibrato from this shows up the funny LFO shape; rather than a regular up/down waveform, it's more like pressing down on then letting go of a whammy bar.
I've had the LA on my build list for quite some time now, will have a deeper look at this and see which one to actually build.
Quickly thrown together onboard pot PCB layout with plenty of spacing for easy building... i've learnt i'm not too great with laying out efficiently for PT2399s today.
Will fit a 1590B with a battery no problems, PCB mounts to the back of the board.
Unverified of course.
(http://i898.photobucket.com/albums/ac182/Scruffie_Crow/OneChipChorusSS.gif?t=1311718848)
(http://i898.photobucket.com/albums/ac182/Scruffie_Crow/OneChipChorusPCB.gif?t=1311720895)
49.53 x 48.26mm
The Clip Sounds Great James!
Edit: Just seen the note about the 10uF Output cap, now added to the PCB transfer (It's just before the output, not updated the SS)
Shrunk the board size down a bit aswell otherwise it's exactly the same.
Quote from: anchovie on July 26, 2011, 05:28:34 PM
Vibrato from this shows up the funny LFO shape; rather than a regular up/down waveform, it's more like pressing down on then letting go of a whammy bar.
That must be why I like it. I like to do subtle wavering of chords with my whammy bar. This circuit kind of has that feel to it.
That sounds nice.
I wonder if my 2399's will work in this circuit.
Anchovie,that clip sounded great reminded me of Radiohead.
While searching for something entirely unrelated just now I came across this post and thought it was quite funny :icon_mrgreen:
Quote from: frequencycentral on November 03, 2010, 03:28:41 PM
I dare anyone to design a lower parts count chorus. :icon_biggrin:
You two better fight it out! :icon_lol:
Dude, this is too awesome. I have an idea for a badazz enclosure for it... :icon_twisted:
Hmm... should call it the Cherub Chorus ;D
Man, that's awesome! Thanks for the work. The noise ensemble is one of my favorite pedals. Can't wait to play with this one...
Awesome!!! Very nice clip! ;)
building it right now....
I think there is an error in the schematic. There should be another 10uf from the junction of the 22k and 10uf to pin 14, right? I think it's there in your vero layout, but those make my head spin. In the current schem there is no feedback path for the PSO.
Here's a sim of the LFO. (http://www.falstad.com/circuit/#%24+1+5.0E-6+119.19350207351468+50+5.0+43%0Aa+256+160+384+160+0+15.0+-15.0+1000000.0%0Ar+256+96+384+96+0+1000000.0%0Aw+384+96+384+160+0%0Aw+256+96+256+144+0%0Aw+256+144+160+144+0%0Ac+160+256+256+256+0+1.0E-5+-0.03082970829821321%0Ac+256+256+352+256+0+1.0E-5+1.1759418159768622%0Ac+352+256+432+256+0+1.0E-5+2.2282164769598802%0Aw+432+256+432+160+0%0Aw+432+160+384+160+0%0Ag+256+176+256+192+0%0Ar+160+144+160+256+0+1000.0%0Ar+256+256+256+336+0+1000.0%0Ag+256+336+256+352+0%0Ag+352+336+352+352+0%0Ar+352+256+352+288+0+22000.0%0Ar+352+288+352+336+0+33000.0%0A174+448+288+416+352+0+100000.0+0.0050+Resistance%0Aw+352+336+416+336+0%0Aw+416+336+416+320+0%0Aw+448+288+352+288+0%0AO+432+160+512+160+0%0Ao+21+1024+0+34+5.0+9.765625E-5+0+-1%0A)
It's pretty solidly a sine, so I guess the strange method of modulating contributes to its non-linearity. I think the sound is fine the way it is, but out of curiosity did you try modulating the reference voltage with it after you discovered it wasn't necessary?
Quote from: Taylor on July 27, 2011, 01:38:42 AM
I think there is an error in the schematic. There should be another 10uf from the junction of the 22k and 10uf to pin 14, right? I think it's there in your vero layout, but those make my head spin. In the current schem there is no feedback path for the PSO.
Thanks for spotting that!
Updated schem, courtesy of the wonders of MS Paint:
(http://i53.tinypic.com/11826br.jpg)
I've added the output cap, too. Scruffie: hope it isn't a big headache to update your layout.
:lol: Maybe if you draw and picture it, it'll be easier. Oh! the good times, when I was young there were no computers for everyone...
Quote from: Taylor on July 27, 2011, 01:38:42 AM
I think the sound is fine the way it is, but out of curiosity did you try modulating the reference voltage with it after you discovered it wasn't necessary?
I didn't, as the Vref pin is the ground for the LFO. I originally had it set up to inject the LFO directly into pin 6. The happy accident occurred through removing that connection with the power still on and the guitar on my lap - "Hey, those pings and clunks still have a chorus effect on them!".
Quote from: Scruffie on July 26, 2011, 07:55:06 PM
While searching for something entirely unrelated just now I came across this post and thought it was quite funny :icon_mrgreen:
Quote from: frequencycentral on November 03, 2010, 03:28:41 PM
I dare anyone to design a lower parts count chorus. :icon_biggrin:
You two better fight it out! :icon_lol:
Yeah, who would have thought it? Pure genius to use the built in opamps as a PSO.
Now, I dare anyone to design a lower parts count chorus than James's. ;D
.
Quote from: frequencycentral on July 27, 2011, 04:18:01 AM
Quote from: Scruffie on July 26, 2011, 07:55:06 PM
While searching for something entirely unrelated just now I came across this post and thought it was quite funny :icon_mrgreen:
Quote from: frequencycentral on November 03, 2010, 03:28:41 PM
I dare anyone to design a lower parts count chorus. :icon_biggrin:
You two better fight it out! :icon_lol:
Yeah, who would have thought it? Pure genius to use the built in opamps as a PSO.
Now, I dare anyone to design a lower parts count chorus than James's. ;D
Ok, I'll swap those two 10k resistors with a 20k trim pot set to its middle position, and the 22k+33k combo with a 50k trim pot :D
Quote from: Perrow on July 27, 2011, 05:01:22 AM
.Quote from: frequencycentral on July 27, 2011, 04:18:01 AM
Now, I dare anyone to design a lower parts count chorus than James's. ;D
Ok, I'll swap those two 10k resistors with a 20k trim pot set to its middle position, and the 22k+33k combo with a 50k trim pot :D
Eh, don't bother. I think you'll find that Bach (http://en.wikipedia.org/wiki/Jesu,_meine_Freude) already designed a 5-part chorus quite some time ago.
Quote from: Taylor on July 27, 2011, 05:05:04 AM
Eh, don't bother. I think you'll find that Bach (http://en.wikipedia.org/wiki/Jesu,_meine_Freude) already designed a 5-part chorus quite some time ago.
I've heard of a one part chorus, a chorus line to be exact :D
Quote from: Perrow on July 27, 2011, 05:01:22 AM
Ok, I'll swap those two 10k resistors with a 20k trim pot set to its middle position, and the 22k+33k combo with a 50k trim pot :D
...and I'll assume that everyone's using a well-regulated 5V supply and that the polarity cannot be changed, losing the 1N914, regulator and 100uF! :icon_mrgreen:
The 20k pot idea is one that I was going to suggest as a possible mod to give a wet/dry balance, or as Taylor suggested you can replace the dry mix resistor with a switch to get vibrato. The 22K resistor spot does need to contain some value as if you just have a pot and set it to zero ohms, the LFO freezes and can only be restarted by backing off the pot and cycling power. Simulation suggested at least 100 ohms but I don't know what the true minimum is in practice - I settled on 22K as that gave me the most depth without getting distortion on each LFO pulse (note: noise musicians may want to exploit this "rhythmic screech" feature!).
Some other notes:
- The 10uF caps from pins 7 & 8 are obviously way higher than the datasheet values; I found in this circuit that they cut out a lot of background hiss.
- The 10uF from pin 2 can be increased to lower the LFO rate range (maybe set this to 100uF and have a switch to add 10uF in series?)
- If you don't mind a bit of background noise, the 100nF coming from the 4.7K resistor can be lowered for a brighter wet sound.
Just when you think you're 'done' building for a while...
I can see this going on my breadboard this evening.
...then probably getting built :icon_lol:
Thanks for sharing your ideas!
Wow nice work. Cool building block. PSO's are tricky things. Make sure that the LFO doesn't fade out after running for an hour.
Quote from: ~arph on July 27, 2011, 08:24:27 AM
Make sure that the LFO doesn't fade out after running for an hour.
I accidently left the power on for 20 hours and it was still chorussing when I came back to it!
Very good!
Nice project!!! the OCC!!! ;D
Yeah I'm down wit it. 8)
Quote from: anchovie on July 27, 2011, 02:14:43 AM
I've added the output cap, too. Scruffie: hope it isn't a big headache to update your layout.
A little, but I got there in the end, i'm not so keen on where I had to put it but ah well, aslong as it works!
Here's the new PCB & SS then
(http://i898.photobucket.com/albums/ac182/Scruffie_Crow/OneChipChorusSS-1.gif?t=1311780102)
(http://i898.photobucket.com/albums/ac182/Scruffie_Crow/OneChipChorusPCB-1.gif?t=1311780104)
49.53 x 49.53mm
I guess Scruffie beat me to it, but I was almost done with mine, so I thought I would go ahead, finish it up, and post it. It "should" fit in a 1590A based on the dimensions on the hammond site (I'm not crazy enough to fool with the A size enclosures, so I can't say for sure). All the electros should lie flat.
(http://i262.photobucket.com/albums/ii81/kearns892/OneChipLayout.png)
(http://i262.photobucket.com/albums/ii81/kearns892/OneChipTransferpng.png)
Transfer is 1.3 in x 2.1 in (33.0mm x 53.3mm)
Unverified as of yet
"Lush" knob could lose a resistor, I think...
(at 10u-10u, remove the 22k, 33k, and pot) From the 10u-10u, take a 50k pot, CCW lug, and a 39k resistor. Tie the resistor's other end to the wiper of the pot, and tie the CW lug to the VR rail. 50k and 39k= about 22k (just under). So, all the way down, you have 50k, which is just a little more than 22k+(33k and 100k)=24k, and all the way up you are sitting at just under 22k.
;D
Quote from: Earthscum on July 28, 2011, 02:16:04 AM
22k+(33k and 100k)=24k
You have just forgot to add those 22k here, it should be 46k (just for the record, it's obviously "typo").. T.
Congrats James to this design, brilliant idea and it sounds really sweat!
Would you mind to make short sample with heavy distorted guitar, please?
Btw. thanks to additional 4k7 (output LPF) on the wet path and R11=R12=10k you don't get exact 1:1 dry/wet mix (wet is cca 3.3dB weaker), is it on purpose?
Cheers, T.
@james, love it, nice n clean chorus.....brilliant. :icon_cool:
Quote from: Thomeeque on July 28, 2011, 05:01:33 AM
Congrats James to this design, brilliant idea and it sounds really sweat!
Would you mind to make short sample with heavy distorted guitar, please?
Btw. thanks to additional 4k7 (output LPF) on the wet path and R11=R12=10k you don't get exact 1:1 dry/wet mix (wet is cca 3.3dB weaker), is it on purpose?
Cheers, T.
Thanks!
I did settle on the 4.7K after trying various resistor/cap pairs to get the same cutoff frequency - that dry/wet mix is my personal preference with the pitch movement of the wet signal being just short of really obvious. As has been mentioned, you could always replace the two 10K mixer resistors with a pot to vary the balance.
I'll get a high-gain sound sample done this evening if my wife has stuff she needs to do on her own, otherwise I'll take a break from being antisocial in the garage and wait until the weekend! :D
Quote from: anchovie on July 28, 2011, 05:26:18 AM
I did settle on the 4.7K after trying various resistor/cap pairs to get the same cutoff frequency - that dry/wet mix is my personal preference with the pitch movement of the wet signal being just short of really obvious. As has been mentioned, you could always replace the two 10K mixer resistors with a pot to vary the balance.
Sure sure, I just wanted to know where this comes from (as "normal" default chorus ration is 1:1), thanks! Looking forward for the samples, good luck, T.
And the build list gets longer...
Great design James!!!
That sounds very good! 8)
Quote from: Thomeeque on July 28, 2011, 04:37:23 AM
Quote from: Earthscum on July 28, 2011, 02:16:04 AM
22k+(33k and 100k)=24k
You have just forgot to add those 22k here, it should be 46k (just for the record, it's obviously "typo").. T.
Doh! Yep. Last thought before I went to bed last night, surprised I got it that complete, lol.
So, 1 pot can replace 2 10k resistors, and we can take another resistor away from the PSO. Without simplifying the PSO, I think that is about it for shaving parts. Too cool!
BTW, my thoughts on the PSO... You're using the internal voltage reference, thus you are modulating it with out of phase signals, which we typically only use one of for the output. This, I think, accounts for the unique sweep. You have current from the rejected highs of the wet signal, and the bottom of the resistors that are injecting 2 shifted out of phase LF signals. The highs from the wet signal may be contributing a significant amount to the PSO signal, helping to create the "warble". Either way, it's very sweet sounding, indeed!
I gotta say... Sorry, Zombie Chorus... I think I found my build. I'll use the PLL for something else, lol.
I breadboarded this.
The chorus works,but its covered with noise.
A static,mixed with distortion that pulses in and out ,but it doesnt sound in sync with the chorus.
The static pulses about 1 time per 1.5 secs roughly.
Double checked everything,more power filtering seemed to help a little.
But still really bad.
Any ideas ?
The noise I found when I was tweaking on the breadboard was related to the LFO, which is where the 22K resistor to limit the Lushness control came from. I take it you're getting noise no matter where the control is set?
Has anyone built it on to a pcb yet?
Sounds like the LFO is dragging the bias too close to the rails at some point.
I have a super compact PCB (1.25"x1.5") to finish on Monday, and I'll try it out. I can't decide if I wanna do my PCB AND the others, or just do my layout... I dig the 1590A layout... looks like it may fit for a mod to a DOD pedal I'm doing. My layout is set up for a add-on to a friend's pedal, which may be getting the same treatment.
mmhhh now there's little angel and a tini winny angle hear! love the sound man thank you so much! Congratss too
Quote from: anchovie on July 30, 2011, 06:39:08 AM
The noise I found when I was tweaking on the breadboard was related to the LFO, which is where the 22K resistor to limit the Lushness control came from. I take it you're getting noise no matter where the control is set?
Yes,noise no matter where its set.
The lush control does work.But doesnt change the noise.
I thought it was the LFO noise becuase of the cycle.
But instead of a thump or tick ,its static and distortion that cycles over and over.
I connected pin 4 to pin 3 and that helped alot but it also reduced the chorus effect.
Hmm, I did wonder what the risk of using the chip for something it wasn't designed to do would be, in terms of production variations. These are complete guesses: what happens if you increase the cap value from pin 2 to ground, and what happens if you swap the pin 7 & 8 caps for the recommended 100n?
You could add a 4.7nF cap from the output to ground, which would at least give you *some* low-pass filtering to reduce PT noise.
@Bryan - is it in phase with the LFO? Basically, does it cycle within some kind of consistency with the LFO? It sounds like it cycles slower than your LFO.
I'm thinking along the same lines as James. Maybe drop down to 1uF's on the mod/demod pins? 100u on the Vr pin (2). The 100u may help keep the LFO from dragging the VR so close to the rails, if that's the issue.
Last time I had a PT do something like that,it was powering up and down. I figured out I had some stuff backwards , lol. I cannot believe the amount of abuse I have put my original chip through. The newer ones don't like being molested like that. Wish we could get our hands on a group buy of old stock from Princeton.
Congratulations ! A very nice sounding chorus - worth to make a try, indeed...
Quote from: Earthscum on July 31, 2011, 11:21:23 AM
The newer ones don't like being molested like that. Wish we could get our hands on a group buy of old stock from Princeton.
I bought a couple of tubes of them about 3 years ago and I'm still getting through them, I'll have to get some new ones to see how they compare (I noticed in the Little Angel thread about the delay resistor spec now being 1K minimum despite the delay time table still having an entry for 0.5R!).
Who'd have thought we might end up with legendary "mojo" karaoke echo chips? ;D
The new ones have weak pins too :( not too breadboard friendly
Quote from: anchovie on August 01, 2011, 02:03:55 AM
Quote from: Earthscum on July 31, 2011, 11:21:23 AM
The newer ones don't like being molested like that. Wish we could get our hands on a group buy of old stock from Princeton.
I bought a couple of tubes of them about 3 years ago and I'm still getting through them, I'll have to get some new ones to see how they compare (I noticed in the Little Angel thread about the delay resistor spec now being 1K minimum despite the delay time table still having an entry for 0.5R!).
Who'd have thought we might end up with legendary "mojo" karaoke echo chips? ;D
Yeah, the first chip I bought was really warm and lush. It gave an almost 'tape-like' sound, sort of mid-90s U2 sort of sound.
I bought a chip last week and it sounds like Jive Bunny. I mean, there *must* be some Mojo in there, right?
:icon_wink:
I really like the sound of this. I was going over the Scruffie pcb before I etch it. Could you check the pad for the minus side of the 100uf capacitor going from pin 1. It's sitting between pin 2 and pin 3 at the moment and looks like it is connected to both. Should it be moved down a bit so that it is just connected to pin 3?
Quote from: Pigyboy on July 30, 2011, 07:02:57 AM
Has anyone built it on to a pcb yet?
Waiting on this as well. This whole project looks very promising ;)
do we need some mix on this? for more versatility?
Replacing the two 10K mixer resistors with a pot was mentioned earlier in the thread.
R13 on the vero is listed as 10K while on the schematic it looks like it is 100K. What is the intended value?
Well spotted! Should be 100K as per the schematic.
Has anyone verified Scruffie's or Kearns' PCB layouts on Page 2?
Has anyone else got this working on a breadboard, even? :-\
Here's another take on the one chip chorus. This one has deeper modulation, so it generates a very thick warble, more like the deep settings on a LA. It also has an improved latch-up fix that may be useful for other projects.
(http://i81.photobucket.com/albums/j207/merlinblencowe/OneChipChorus.jpg)
Quote from: Govmnt_Lacky on August 03, 2011, 10:30:57 AM
Has anyone verified Scruffie's or Kearns' PCB layouts on Page 2?
Don't think so, atleast no one's mentioned it to me.
I'll verify it if you wanna etch me one :icon_lol:
Quote from: merlinb on August 03, 2011, 11:03:32 AM
Here's another take on the one chip chorus. This one has deeper modulation, so it generates a very thick warble, more like the deep settings on a LA. It also has an improved latch-up fix that may be useful for other projects.
(http://i81.photobucket.com/albums/j207/merlinblencowe/OneChipChorus.jpg)
Damn that looks nice... looks like i'll be making another PCB layout this evening... and using the breadboard if I can clear some space.
Quote from: anchovie on August 03, 2011, 10:59:39 AM
Has anyone else got this working on a breadboard, even? :-\
Same as above, if I can get some space on the breadboard i'll try tonight... it's kindaaa full at the moment.
Just saw this thread...
I'm amazed... Congrats on this new design!
Quote from: merlinb on August 03, 2011, 11:03:32 AM
(http://i81.photobucket.com/albums/j207/merlinblencowe/OneChipChorus.jpg)
Is this drawing correct? I'm trying to figure out how the LFO works here and I don't see it.. LTSpice neither.. Thanks, T.
Quote from: anchovie on July 26, 2011, 03:44:08 PM
I wondered if it would be possible to make a chorus effect using a PT2399 and no external op-amps and the answer is yes! Instead of using the internal amplifier intended for the output mixer, I've given it a new role in a phase shift oscillator. I originally intended to use the LFO output to modulate delay time, but the nice surprise was that there was no need - the oscillator uses the chip's Vref pin (famously exploited by frequencycentral in the Little Angel as a place to inject modulation) as its ground point and, just by being there, it makes the PT2399 wobble.
This is how he did it Thom ;)
I was going to try and etch my board today, but I am not sure I have enough PTs to complete this and the other PT based projects I'm rushing to finish.
Quote from: Govmnt_Lacky on August 03, 2011, 01:55:02 PM
Quote from: anchovie on July 26, 2011, 03:44:08 PM
I wondered if it would be possible to make a chorus effect using a PT2399 and no external op-amps and the answer is yes! Instead of using the internal amplifier intended for the output mixer, I've given it a new role in a phase shift oscillator. I originally intended to use the LFO output to modulate delay time, but the nice surprise was that there was no need - the oscillator uses the chip's Vref pin (famously exploited by frequencycentral in the Little Angel as a place to inject modulation) as its ground point and, just by being there, it makes the PT2399 wobble.
This is how he did it Thom ;)
Well, that's how
anchovie did it, but I'm asking about Merlin's magic, that's completely different circuit ;) T.
Quote from: Thomeeque on August 03, 2011, 02:04:44 PM
Well, that's how anchovie did it, but I'm asking about Merlin's magic, that's completely different circuit ;) T.
SLAPS FOREHEAD PROFUSELY!!!!!! :icon_redface: :icon_lol:
Quote from: Thomeeque on August 03, 2011, 01:51:55 PM
Is this drawing correct? I'm trying to figure out how the LFO works here and I don't see it.. LTSpice neither.. Thanks, T.
Pah, there's always something! Resistor in the wrong place- drawing has been corrected. (If it still looks the same try going directly to http://i81.photobucket.com/albums/j207/merlinblencowe/OneChipChorus.jpg)
It's a relaxation oscillator, just like in most modulation effects, e.g. Phase 90.
What resistor was moved and where? I do not see a change even after clearing history ???
Quote from: merlinb on August 03, 2011, 03:33:51 PM
Quote from: Thomeeque on August 03, 2011, 01:51:55 PM
Is this drawing correct? I'm trying to figure out how the LFO works here and I don't see it.. LTSpice neither.. Thanks, T.
Pah, there's always something! Resistor in the wrong place- drawing has been corrected. (Clear your browsing history if it still looks the same)
It's a relaxation oscillator, just like in most modulation effects, e.g. Phase 90.
Actually, integrator capacitor 4u7 is in wrong place, it should lead to pin 13 not 14 of PT2399 (I see only thumbnail in your gallery (http://s81.photobucket.com/albums/j207/merlinblencowe/) corrected, full picture is still the old one - some photobucket issue I guess).
Funny, this LFO works only thanks to weak internal reference voltage divider :) If it was harder, it would not tick (voltage at positive input of LFO op-amp must be alternated for this type of oscillator).
Problem is, that you don't get triangles on the reference voltage this way (triangles are only at the integrator capacitor) - what you get there are rounded squares*..
(http://thmq.mysteria.cz/diystompboxes.com/PT_LFO2_emu.gif)
That's why it sounds as you describe it (
it generates a very thick warble) probably..
T.
* Edit: But now I see that it can be rounded almost to sinusoidal wave (when increasing C1 and C3).. and of course I don't know how exactly internal reference voltage source looks..
Quote from: merlinb on August 03, 2011, 11:03:32 AM
Here's another take on the one chip chorus. This one has deeper modulation, so it generates a very thick warble, more like the deep settings on a LA. It also has an improved latch-up fix that may be useful for other projects.
(http://i81.photobucket.com/albums/j207/merlinblencowe/OneChipChorus.jpg)
I *think* this is based on the updated version. Please check before attempting - it's late - I'm tired.
(http://dl.dropbox.com/u/967492/EntropyPCB.gif)
(http://dl.dropbox.com/u/967492/EntropyPnP.gif)
How crucial is it to use a BC337? Would substitution with a 2N series transistor be possible?
Quote from: frequencycentral on August 03, 2011, 09:51:03 PM
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!
QuoteHow crucial is it to use a BC337? Would substitution with a 2N series transistor be possible?
Not at all crucial, any NPN should work.
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?
Interesting... I get the "Page cannot be found" annoyance when I paste the link ???
EDIT: Nevermind... it is my work computer. DAMN Firewalls :icon_mad:
Quote from: frequencycentral on August 04, 2011, 08:23:24 AM
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.
Not sure if I'll have it populated soon or not, have a show this weekend, and some stuff to do tonight, but...
(http://img8.imageshack.us/img8/8225/image08042011132415.jpg)(http://img829.imageshack.us/img829/2946/image08042011132441.jpg)
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"?
Quote from: Earthscum on August 04, 2011, 03:57:28 PM
Not sure if I'll have it populated soon or not, have a show this weekend, and some stuff to do tonight, but...
(http://img8.imageshack.us/img8/8225/image08042011132415.jpg)(http://img829.imageshack.us/img829/2946/image08042011132441.jpg)
Wheyy, glad to see my layout being used :D 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.
@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!
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.
Quote from: Earthscum on August 05, 2011, 10:53:51 PM
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.
Quote from: Earthscum on August 05, 2011, 10:53:51 PM
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!
Quote from: Scruffie on August 06, 2011, 01:25:40 AM
Quote from: Earthscum on August 05, 2011, 10:53:51 PM
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.
(http://i898.photobucket.com/albums/ac182/Scruffie_Crow/OneChipChorusPCB.gif)
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. :icon_biggrin:
The sound clip sounded great imo !
Does anyone know if or when the Vero pic will be verified ?
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).
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:
(http://i605.photobucket.com/albums/tt137/pinkjimiphoton/1chiptop.jpg)
(http://i605.photobucket.com/albums/tt137/pinkjimiphoton/1chipbot.jpg)
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!!!!! :icon_biggrin:
Quote from: Yazoo on September 11, 2011, 02:01:58 PM
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. :icon_biggrin:
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
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.
Thanks Yazoo,
I have a good batch from Smallbear here to use up first.
duuuuude.... ???
it was an almost microscopic break in one of the rails!!! :icon_eek: :icon_redface: :icon_rolleyes:
but,
now it works great!! :icon_twisted: :icon_twisted:
reminds me of my old boss dimension d!
the vero is now VERIFIED, fwiw!! :icon_mrgreen:
thanks anchovie!! gotta box it up, will try and post clips this week.
;)
Quote from: pinkjimiphoton on September 17, 2011, 10:51:11 PM
reminds me of my old boss dimension d!
This tiny circuit sounds like a Dimension D? Long live DIY!
yah, it's really subtle without a lot of modulation on chords, but is very noticeable on single note stuff.
and if ya stack the pt2399's up, you get a really nice "doubler" effect that's alot like the old "boston" sound.
stack up 5 or more, and it becomes a distinct slapback with modulation that sounds remarkably like a short tape echo.
really really nice box...
and the vero layout is VERIFIED...or is that VERO fied?
hi jimi:
cool, what is it like level wise compared to bypass signal, is there a noticable jump or slump?......i mean would you recommend the mix/volume/blend mod?..
been pondering on this today..
don't know yet, i haven't boxed it yet with bypass...today or tomorrow rob.
I have a board of Scruffies layout here and want to build this now I have some new PT2399's.
How are you guys stacking the PT2399's? First I have heard of doing this. Can you stack them on Rick's Little Angel?
i'd imagine you could stack 'em on anything that uses them. with delay chips i believe it doubles the delay time. all i did was stick one on top of the other so the pins all lined up just to check it out. if i had kept it, would have just quickly soldered them one on top of the other. 2 chips gave enough delay to sound like a double, 3-5 chips sounded almost like a really quick unity slap echo...
for vst guys, it sounded like latency....lol
Quote from: pinkjimiphoton on September 18, 2011, 09:25:07 PM
i'd imagine you could stack 'em on anything that uses them. with delay chips i believe it doubles the delay time. all i did was stick one on top of the other so the pins all lined up just to check it out. if i had kept it, would have just quickly soldered them one on top of the other. 2 chips gave enough delay to sound like a double, 3-5 chips sounded almost like a really quick unity slap echo...
for vst guys, it sounded like latency....lol
Why not just increase the 1k between pins 4 and 6?
Quote from: pinkjimiphoton on September 18, 2011, 12:01:23 PM
the vero layout is VERIFIED...or is that VERO fied?
Thanks for doing this!
@taylor, so a pot between 4-6 would give a delay too?...
Well, I haven't built this, but I would assume so based on the way the chip works in normal apps. The only thing is that the filtering is not designed for longer times so (without simulating it, just guessing) I'd expect it to get a little nasty as you extended the delay time, with less lowpass filtering than in something like the Echo Base.
cheers, i'll have to bread it and try a few things out. thanks.
Quote from: Taylor on September 18, 2011, 11:36:16 PM
Quote from: pinkjimiphoton on September 18, 2011, 09:25:07 PM
i'd imagine you could stack 'em on anything that uses them. with delay chips i believe it doubles the delay time. all i did was stick one on top of the other so the pins all lined up just to check it out. if i had kept it, would have just quickly soldered them one on top of the other. 2 chips gave enough delay to sound like a double, 3-5 chips sounded almost like a really quick unity slap echo...
for vst guys, it sounded like latency....lol
Why not just increase the 1k between pins 4 and 6?
i'm a newb, dude, i didn't know you could do that!! ;) my pampers still have fuzzfaces on 'em, ya know? ;)
Quote from: anchovie on September 19, 2011, 01:47:40 AM
Quote from: pinkjimiphoton on September 18, 2011, 12:01:23 PM
the vero layout is VERIFIED...or is that VERO fied?
Thanks for doing this!
my pleasure, thanks for sharing such a very groovy circuit!! i like it so much, it's going on my pedalboard today bro.
so...add the tag to your vero....VERIFIED!!
thinking about building a couple more and messing with them a little...doubling the delay time makes a really nice doubling effect! ;)
i boxed it up, there isn't really a volume drop when engaged i don't think...i think it's just the psychoaccoustic phenomenon of it sounding so good, yet so subtle.
i haven't tried it into a big amp yet, just my old pignose 3060, it sounds great there...really organic. almost TOO subtle..more noticeable on single notes than chords.
Hello you guys,
Together with Chris from El Musico Loco I'm working on a One Chip Chorus. Chris made the pcb for me, and I will try and make it work. That last thing isn't happening yet.
I put on all of the components on the board, and hooked all the others things up like the in and output etc.
So when I power on the one chip chorus, i have a bypass sound, but when it's engaged I only hear some hiss that slightly chances when I play some chords!
Chris said to post my problem on here because you guys could probably help me out here.
Some pics of my board.
Top:
(https://lh6.googleusercontent.com/-fj-wa8BuJAE/Tnx1X5fu3PI/AAAAAAAAA9E/UCa91kKJuyA/s640/DSC01470.JPG)
Bottom:
(https://lh5.googleusercontent.com/-2rlJIoFfVlI/Tnx1XWP_VCI/AAAAAAAAA9A/v68jfXkmdmc/s640/DSC01472.JPG)
Thanks,
Cheers,
Tim
Quote from: rhcp_schipper on September 23, 2011, 08:10:07 AMChris said to post my problem on here because you guys could probably help me out here.
Voltage measurements for the IC pins, please!
Quote from: anchovie on September 23, 2011, 08:57:13 AM
Quote from: rhcp_schipper on September 23, 2011, 08:10:07 AMChris said to post my problem on here because you guys could probably help me out here.
Voltage measurements for the IC pins, please!
Sorry, I fairly new here. Can you explain how to? Thank you.
Take readings from each pin to ground and post them up :icon_wink:
Quote from: Pigyboy on September 23, 2011, 09:00:15 AM
Take readings from each pin to ground and post them up :icon_wink:
Chris, will do that! Thanks for the info!
Hey Tim,
Can you post pics of the rest of your off board wiring along with the voltages? Everything looks good on the board to me...
check for solder bridges between the tracks, or an open somewhere..sometimes a trace can have an almost imperceptible break and screw ya up.
check the voltages, if they're not too far off, it may be the chip. there's an audio op amp section to the chip check around there especially...i'm on the wrong computer to look up the data sheet for ya, but just hit google for pt2399 data sheet for pinouts and a ballpark of where the voltages should be in your build.
looks nice, man! you'll get it. ;)
I won't have time to verify this for a bit, but here is a 1590A layout for 1/8W resistors and monolithic/MLC caps. Should fit pretty easy.
(http://i232.photobucket.com/albums/ee47/madbeanpedals/th_OCC_1590A.gif) (http://s232.photobucket.com/albums/ee47/madbeanpedals/?action=view¤t=OCC_1590A.gif)
Here are the voltages I've measured and the pics of the wiring.
The voltages are way off the other voltages one page back, so thats not a good thing.
1 4.94 16 0.12
2 0.03 15 0.12
3 0.0 14 0.03
4 0.00 13 0.03
5 0.00 12 0.12
6 0.00 11 0.05
7 0.08 10 0.03
8 0.11 9 0.03
The Pics of the wiring.
Top:
(https://lh5.googleusercontent.com/-MAuXz2IzYUk/Tny2j1-VVxI/AAAAAAAAA9w/K8GRgtoR7Dk/s640/DSC01474.JPG)
Bottom:
(https://lh3.googleusercontent.com/-ZK5srvnwmQY/Tny2j0NTrTI/AAAAAAAAA90/YahuEQQS5FI/s640/DSC01475.JPG)
Tim
Hey Tim,
Unhook the switch section and just try to get it to work with and in/out only. Eliminate everything else and see what you get...
Quote from: Pigyboy on September 23, 2011, 03:44:41 PM
Hey Tim,
Unhook the switch section and just try to get it to work with and in/out only. Eliminate everything else and see what you get...
Will try that tomorrow! Hope I'll get it to work!
I've just unhooked the switching section from the PCB, and re-soldered every connection on the pcb.
Now I can get sound out of the thing, but I don't think it all right yet. At home I've got 3 Pt2399's, with one the of the Pt's I only get clean sound(no noticeable chorus at all), with another I get no sound at all, and with the last there is a chorus sound(no as nice as the the sound clip sounds), and when I have the pot at max the chorus pops every cycle it makes.
Extra info: That last Pt2399 came out of the little angel chorus I've bought from El musico Loco. This Pt2399 has the known startup problem, maybe this is some usable information.
For testing I'm going to buy some new Pt's!
Cheers,
Tim
tim,
mine drove me nuts too...
it wasn't really noticeable on chords at all...do you hear it more on single notes than chords?
Quote from: pinkjimiphoton on September 24, 2011, 12:40:38 PM
tim,
mine drove me nuts too...
it wasn't really noticeable on chords at all...do you hear it more on single notes than chords?
When the effect is working the chorus is pretty thick and good noticeable! Not only on single notes, especially when the chorus is maxed out.
Maybe I have to recheck all the solder joints again. Can't be a bad thing to do.
My 2...
I have not built this particular version of a PT-based chorus however, I have built several of FCs Little Angels and I have found 1 undeniable truth...
IT ALL COMES DOWN TO THE CHIP!
Some chips just "work better" than others. Out of the 6 or 7 angels that I have built, I have probably seen 4-5 different results.
true that. i tried the 5 chips i had, and every one was different...so i bought 5 more from a different vendor, so i could see which one is "the one".
Mojotastic PT2399? Awesome!
hi guys,
i think i got something screwed up, so advice would be hip, my newb posterior is afu atm.
it definitely works...it passes signal...but i can't seem to hear it warble like on the demo.
with headphones on, i can hear a chorus effect slightly, but the "lush"control doesn't seem to do anything.
i tried swapping out the 2 10k mixer resistors and subbing a 50 k pot (all i had atm) but didn't seem to make any diff at all...if i turned it toward the "wet" signal, just kinda lost volume some. still no real warble.
i did mess with the resistor between pins 4 and 6 some...and ended up wiring in a 50k pot instead. now i can dial up a distinct one slap echo maybe a 1/4 second long or so. so i know the chip is working. for $#*^s and giggles, i tried feeding back the output to the input for a couple repeats...a little noisy, but very warm and tape echo-y. could get about 3 slaps. messed around with trying to inject the output at different points back into the circuit with a couple interesting results, but nothing really useful...
sorry for the rambling on and on...
what i guess i need to know is what parts should i check to see if the lfo is working? i know the chip is working, but don't have enough knowledge yet to really understand how to check the lfo.
advice as always appreciated!!
thanks guys...
k, tried a couple things...read on at your own peril.
added a 50k pot in series with r1 as a voltage divider...can go from stock, to doubling, to one slap about a half a second. at long times, it's noisy and almost unusable. i like it tho, reminds me of a tape echo. ;)
also added a 250k pot between pin 7 and the bottom rail, with the third lug grounded. this adds to the "lush" control, and seems to be a master volume and boost for the delayed signal. seems to add a lot of compression, too.
like i said, at your own risk. i am a newb having fun, to me these are happy accidents.
i love this thing, anchovie. :icon_mrgreen:
thanks!!
edit: also shorted across r9, it wasn't needed on my build. chinese pt's....who knows what they are... lol
^ nice one jimi, i haven't had time to bread this yet, been too busy.. ::)
when the delay is long is it the same-ish as a rebote delay?...i know its an inherent trait of the pt2399 to get dirty on long delays but i'd like mine to be a chorus/delay too...coz i'm greedy... ;D
any chance of one of your famous vid demo's on it?... :icon_cool:
hi rob, i will post a video as soon as i can. never tried a rebote, so i don't know...it's a VERY tape like echo, it sounds alot like my echoplex and even warbles some.
if i can get my girl off the laptop with the webcam one of these days...lol...
i need to chase down a very LOUD switch popping problem first..this things been driving me nuts!!
anybody got any tricks for making a feedback loop other than just connecting input and output? if i do that, i get the original and 2 distinct slaps...would a buffer fix that?
no idea how to add more filtering, but the delay gets a weird ascending "zip" sound that's modulated over about a half second...really faint, but noticeable.
i like it best just at the point you can notice a double...sounds awesome.
will try to make a video later...beware of stupid pedal tricks volume....5? 7? lol
please excuse the crappy sound...the soundcard in this laptop sucks.
mods are a 50 k pot between pins 4 and 6, and a 250k pot between pin 7 and the bottom rail, and ground.
i can tell the lush knob works, but just barely. you can actually see where the pt locks up in the video. every time it locks up, it wobbles more. ;)
anyways...
Hey all, before I forget... the micro-sized layout I promised several pages ago, lol. 1.2" x 1.5", scaled for 300 DPI Print. You'll need to mirror the image for toner transfer etching, I have it set up for silk screen transparencies.
I have the ground plane extending under the chip in an effort to isolate the power side from the signal side (at least I think that's what my idea was). Also note either resistors OR trimpot for the output. Lush control is set up as a trimpot in case you want to make a "No-Knob OC Chorus" NoKnOCChor? :icon_rolleyes:
Anyhoo...
(http://img442.imageshack.us/img442/7240/anchovieocc.gif)
@jimi: nice demo as always man....i see what you mean, more of a delay than 'lushy chorus' cool mods though......
shame as anchovies original clip sounds really 'lush'..nice and rich chorus...
and merlin's clip was really warbly...i thought merlin added an anti lock-up thing to it?..off pin 6?...i may be wrong though...anyway, i like that reversey sound too... :icon_cool:
@david: so have you built it?...does it 'chorus'...does it lock up?....can it make tea?... ;D
I promise I'll get round to verifying my own vero layout with my own parts! Finished the new tube amp at the weekend with the intention of doing this next, but I've now got someone's bass amp in the garage that I've been offered money to repair.
Quote from: Earthscum on October 11, 2011, 09:11:52 PM
Hey all, before I forget... the micro-sized layout I promised several pages ago, lol. 1.2" x 1.5", scaled for 300 DPI Print. You'll need to mirror the image for toner transfer etching, I have it set up for silk screen transparencies.
Hey, what software did you use? Is there a possibility to export the pcb to a pdf file, probably by using PDFCreator (http://sourceforge.net/projects/pdfcreator/)? Printing is proved to be better then. ;)
The layout is really fantastic.
Quote from: deadastronaut on October 12, 2011, 03:36:25 AM
@jimi: nice demo as always man....i see what you mean, more of a delay than 'lushy chorus' cool mods though......
shame as anchovies original clip sounds really 'lush'..nice and rich chorus...
and merlin's clip was really warbly...i thought merlin added an anti lock-up thing to it?..off pin 6?...i may be wrong though...anyway, i like that reversey sound too... :icon_cool:
@david: so have you built it?...does it 'chorus'...does it lock up?....can it make tea?... ;D
i want the lushy chorus tho!!
lol!!
it's neat, but i really wanna get the sound of jim's box, not what i ended up with. it COULD be a chip issue, but i tried 10 different ones from 2 different vendors. weird!!
a search on pt2399 led to a pdf from merlin here that explains a LOT of what's going on. if i could find it in my archives of saved info, now,...lol..
I use Illustrator or Inkscape to do my layouts, after creating them by hand on a printed 'perf sheet' and pencil.
I do have it saved as PDF, but nowhere to host. Besides, if you need it any clearer than 300 DPI, you're getting a bit too picky. That is standard 'photo-quality' resolution. The traces aren't anywhere near fine enough to warrant anything higher.
@Earthscum: It looks like the center pin of the regulator is not grounded in your layout. Simple enough to bend the lead over since the ground is right there, just thought I'd point it out for those building using it. Nice layout! I want to build one of these when I get some time.
Quote from: Earthscum on October 12, 2011, 11:47:04 AM
I use Illustrator or Inkscape to do my layouts, after creating them by hand on a printed 'perf sheet' and pencil.
I do have it saved as PDF, but nowhere to host. Besides, if you need it any clearer than 300 DPI, you're getting a bit too picky. That is standard 'photo-quality' resolution. The traces aren't anywhere near fine enough to warrant anything higher.
You're probably VERY right, but you see.. it's just my habit. I'm just sure about the quality of printng when all my pcbs are vectorized in pdfs, and I can simply open up some PDF editor, and put a lot of pcb drawings on one sheet of paper, and it all prints great.
But since you're just right, I won't make any problem with that. Thanks for your briliant layout, I'll be building this soon. ;)
Quote from: pinkjimiphoton on September 17, 2011, 10:51:11 PM
duuuuude.... ???
it was an almost microscopic break in one of the rails!!! :icon_eek: :icon_redface: :icon_rolleyes:
but,
now it works great!! :icon_twisted: :icon_twisted:
reminds me of my old boss dimension d!
the vero is now VERIFIED, fwiw!! :icon_mrgreen:
thanks anchovie!! gotta box it up, will try and post clips this week.
;)
I know this is a little old, but did the break change any of the pin voltages? Trying to troubleshoot mine. I don't get any chorusinfg, though I do get signal passing through.
yes, i was getting maybe 2 volts to the ic
Hi m8s, need your help!!
I've built is as per schematic on 1st page and as per Scruffie layout, it's almost working but.... it takes 4 to 5 secs to become operational! in those secs lot's of noise, whistles etc, then it sound normal (not really as the soundclips, I need to work on that later, though voltages look good). So any known reason for it to be so slow to bristle up!, I don't thinks it's "latching" , just takes time to warm up.
Thx m8s for help
Armando
Edit, I also printed out the whole thread but didn't find any idea....
I think my breadboarded one had a start-up time, just not as severe as yours. The phase-shift LFO didn't give me instant response when changing the pot setting - if I rotated it quickly I'd have to wait for the oscillator to "catch up"!
thx james
though my one is doing this everytime I switch it, I mean the signal not the power, the pot does nothing while I waiting it to warm up.
If it's the LFO, is there any cure to keep the LFO "active" while idle?
I've refreshed all the soldering but still same problem. Is there any voltage I can measure to see what's going on?
Thx
mine is on acid too, i hoped to add it to the pedal board cuz when it works it sounds great...but sometime it just....goes crazy...warbles all over. this seems to be minimized if i run it with a dedicated ps, but i never know if it'll work or not. real temperamental. maybe i need to try it again..;p
Quote from: arma61 on November 10, 2011, 07:07:10 AM
thx james
though my one is doing this everytime I switch it, I mean the signal not the power, the pot does nothing while I waiting it to warm up.
If it's the LFO, is there any cure to keep the LFO "active" while idle?
I've refreshed all the soldering but still same problem. Is there any voltage I can measure to see what's going on?
Thx
I sadly have no idea! Looks like I was really lucky with the one I breadboarded to test the "LFO from a PT2399" theory. I don't even know how a phase-shift oscillator works, I just saw a schematic for one and that it only used one op-amp.
This project should be filed under "experiments" rather than "pedals to gig with". :)
Anyone had any luck with this? I've been chasing the dragon trying to get that great sound from first post but so far have only got what sounds like a slapback echo. No LFO. I've had no luck with perfboard, Madbean's layout or Earthscum's layout. A number of different PT2399s from a few sources...well you get the idea. I've built entire amps in less time :-[
This is destined to become my modern equivalent to a Fuzz Face: "I know it's really simple but I can't get it to sound right..."
I need to go lie down now.
breep, breep, breep.
(crickets)
It seems a better place to stick the lfo is the vco input, pin 6, through a current limiting resistor. I haven't tried it though, just a thought.
When I first had the idea for this, I thought I'd set up the phase-shift LFO and then work out where to inject it into the chip. As it turned out, the LFO uses pin 2 as its ground connection and caused wobble for me anyway so the modulation is more a product of grounding the LFO at Vr rather than feeding the LFO output to pin 2.
I had a lucky break with mine. I'd suggest that anyone else wanting to try the circuit does so on a breadboard, and don't spend more than half a day debugging it. If it doesn't wobble, possibly check the LFO on a scope. If you still can't get it to work, save the headaches and build another chorus! :)
mine works, but it's wicked temperamental...but i added a delay time pot to it, and a little feedback thru a pot...mAkes a nice double, but i can't really get a chorus out of it usually...but sometimes it just goes crazy, sounds like a broken taper delay...cool, but too intermittent to be useful. every power up it makes a weird noise that kinda sounds like bra-aa-aa-aaapzip before it does anything, sometimes it gets stuck there and i have to power it down. it's weird, i tried 15 different pt2399's and they all sound different, 10 from one vendor, 5 from another...and they all work in my echo fine, but not in this circuit. i'd love to see this nut get cracked, cuz when it works it's real nice and silky, almost sounds like doing it with tape.
Quote from: pinkjimiphoton on January 06, 2012, 10:22:49 AM
every power up it makes a weird noise that kinda sounds like bra-aa-aa-aaapzip before it does anything, sometimes it gets stuck there and i have to power it down.
Yupp, getting the same noise and I'm also getting varied results using different chips.
Quote from: pinkjimiphoton on January 06, 2012, 10:22:49 AM
i'd love to see this nut get cracked, cuz when it works it's real nice and silky, almost sounds like doing it with tape.
Anchovie, like Jimi says, I just liked the sound of the original post. I'm not even a big chorus fan, just thought yours sounds killer. The fact that it was dead simple was icing on the cake. I'll shelve it for now but will definitely come back to it.
i don't like chorus either, but this thing, when it works, sounds special...really organic, and not all fake like most choruses.
Perhaps a better way to obtain the sound that I got would be to replicate the LFO shape using an isolated chip and use it with a more stable pt2399-or-whatever delay circuit? I described it earlier as being like someone dipping on the whammy bar repeatedly.
On a scope it looked like a sawtooth with a short fall time and long rise time. Should be easy to set up with a 555 but might introduce ticking into the power supply (CMOS 555 perhaps?). Or another quiet solution that allows the duty cycle to be altered in the right way.
The one-chip challenge that I set myself was fun, but I'm not going to cry if another op-amp or suchlike appears!
Yeah, I'd thought of that. I did a layout for the Dimension P that worked out so at least I have my PT2399 mojo back but the coolest part of this circuit was being in on your "aha" moment. Nice to see one of the forum's regulars dip over the threshold from time to time. Just wanted to validate it.
Well, that and the cool sound clip :icon_cool:
For all the times I've let the magic smoke out, it would be cool to put it back in... :icon_wink:
I just built one up on Vero/Perfboard - sounds really crazy, but I am afraid mine is not working correctly.
Sine wave is very disturbed sounding ( just moves in a very unuseable step ) and it also has pulsing distortion. I love the tone of the Chorus - it just needs to be adjusted.
I want to add mods as well, so this will be a great troubleshoot lesson! Ill post pics this evening.
This is my first post, I am excited to be a member here now, have been at BYOCs forum since 2007.
Patrick G
Welcome Patrick!
I've replied to your PM, Patrick. I'll put the gist of the answer in the thread for posterity!
The electrolytic from pin 2 to ground was a real "trial and error" component for me as it interacted with the whole character of the LFO. In this circuit it does a lot more than just filter Vref! Could be worth trying different values.
Alright Anchovie...
YOU RULE!!
The C2 E.C. Cap in the layout is crucial for fixing the distortion/hiss issue. a 47uf cap fixed all distortion issues, although there is a very faint pulse to it when you have it engaged in the background - but its only audible once the volume on your amp is turned all the way up. A 22 uf was nice, but the background pulse was louder. 100uf was too thin on the Lush signal. 47uf seems to be the sweet spot for getting subtle to lush chorus.
I do have one final issue - I do notice a drop in treble and output volume when I have the circuit going through my break out box compared to my clean signal un affected. - Can this be fixed or is this an issue others have noticed? Also, is there a way to add a Rate knob?
Hey guys, here is my One Chip Chorus all boxed up - I call it the Lunar Chorus (weve had some great moonlit nights here in TX lately, so it fits)
I opted for a 330k instead of 680k, which gives more output. I also changed out the EC from 10uf to 100uf that goes to Pin 2 - eliminates any noise issues and gives you a perfect chorus! Socket these areas and see what you like
I love how it sounds and will get a demo up ASAP!
(http://a5.sphotos.ak.fbcdn.net/hphotos-ak-ash4/s720x720/409119_10150624013300280_677875279_11393924_405388251_n.jpg)
(http://a4.sphotos.ak.fbcdn.net/hphotos-ak-snc7/s720x720/424178_10150613841100280_677875279_11370727_457087461_n.jpg)
That looks amazing!
I'm a bit of a novice, but I've just built this based on the Vero layout on the first page.
I read through the thread and I'm not quite sure why it's not working :(
It passes signal ok, but no chorus effect.
I'll keep fiddling! Thanks heaps for this - i can't wait for it to work!
Is there an updated Vero layout? (I guessed the polarity of the caps...)
Quote from: mwynwood on February 08, 2012, 05:42:15 AM
(I guessed the polarity of the caps...)
You don't need to (and shouldn't!) do that - look carefully at the layout and you'll see a darker stripe on the electrolytics that denotes the negative terminal.
ah! :icon_redface: Thanks for that! I'm used to layouts with the terminals marked + or -
Probably didn't help that I printed it out in low-quality B&W... haha
Mwywood - Thanks for the kind words!
All you need to figure out whats up with your build is an audio-probe - look it up and you'll get somewhere really quick.
Thanks Pat - I've just put together one kinda like the one here: http://www.diystompboxes.com/smfforum/index.php?topic=79707.msg658079#msg658079 (http://www.diystompboxes.com/smfforum/index.php?topic=79707.msg658079#msg658079)
I followed the circuit through, and on the other side of R3, there is no signal (hole 13d on the Vero (http://i55.tinypic.com/oaam41.gif))
I've checked R3 and it's reading 680k on the multimeter, so I assume it's ok.
I don't want to be spoon-fed or waste anyone's time, but if anyone has any good trouble shooting tips or has an idea of a simple beginners mistake I could have made, that would be great :)
Thanks!
Sounds like something connecting to that side of R13 is causing problems to me
Quote from: frequencycentral on August 03, 2011, 09:51:03 PM
Quote from: merlinb on August 03, 2011, 11:03:32 AM
Here's another take on the one chip chorus. This one has deeper modulation, so it generates a very thick warble, more like the deep settings on a LA. It also has an improved latch-up fix that may be useful for other projects.
(http://i81.photobucket.com/albums/j207/merlinblencowe/OneChipChorus.jpg)
I *think* this is based on the updated version. Please check before attempting - it's late - I'm tired.
(http://dl.dropbox.com/u/967492/EntropyPCB.gif)
(http://dl.dropbox.com/u/967492/EntropyPnP.gif)
Any way to slow this one down ?
It's alittle too "wow-wow-wow-wow-wow" all the time.
Plus - a pretty good thump when turned on - even without an LED indicator - gotta check and see if something leaking DC - or maybe I just need an RPD.
edit: plus I'm getting a pretty good volume drop - it doesn't seem to be quite at unity.
Dan
I've been trying to debug my vero layout for a long time now. I've changed chips, traced everything over and over again. I'm just getting farting sounds coming from the pedal.
I've built a lot of pedals before but it always seems that pedals containing PT2399 chips are hard to make.
I'm using PT2399 chips from Tayda. Have any of you tried them ? Out of 10 chips, I've managed to make one rebote delay and that's it. I haven't gotten 3 other rebotes, 2 little angel and one of these circuits to work.
Quote from: geiristudio on February 12, 2012, 07:02:13 PMI've been trying to debug my vero layout for a long time now.
I sympathise! Were you working of this Vero too?
(http://i55.tinypic.com/oaam41.gif)
I wonder if there is an error with it, or if there is an updated version?
I think Photon verified this layout and if you look a few posts up you'll see a finished pedal using the same layout.
Nice
Have to try this one out. But it seems it would be hard to get the LFO to work.
Phase shift oscillators are hard to use in my experience, they will not always oscillate. I don't quite understand this one, I guess I just have to build it and try.
I've never done this before... but I've had a go a debugging by following the instructions here:
http://www.diystompboxes.com/smfforum/index.php?topic=29816.0 (http://www.diystompboxes.com/smfforum/index.php?topic=29816.0)
I'm working off the Vero Layout (http://i55.tinypic.com/oaam41.gif) I posted a few posts above.
It passes sound, but with no chorus effect. ???
I hope I get this right... here goes:
V1
Input = 8.69
Common = 0
Output = 4.97
D1
A = 9.57
K = 8.68
IC1
1 = 4.97
2 = moves between 1.90 and 2.80
3 = 0
4 = 1.75
5 = 4.94
6 = moves between 1.90 and 2.80
7 = 0.20
8 = 4.59
9 = moves between 1.90 and 2.50
10 = moves between 1.70 and 3.10
11 = moves between 0.50 and 3.80
12 = moves between 2.30 and 2.40
13 = moves between 2.00 and 2.90
14 = moves between 1.90 and 2.90
15 = 0.85
16 = 4.78
Thanks for your help :icon_biggrin:
yah, i did verify the vero layout...it works, but of the 20 chips i bought from different suppliers, almost all of 'em were wonky in this circuit..i'd say it's the chips, not the circuit.
i've had everything everyone has described, from lock up to insane distortion to bizzarre noise to even a low-pitched motorboating. switch chips, and it's a different problem.
switch the damn chips to other projects, and they all exhibit issues, too...so it's definitely the chips.
but when ya DO get a good one...it does sound nice.
i could never really get the lush pot to do much, unfortunately, but i think it's more because the damn chip locks up so easily.
i undid the mods i had done to it before, but did make one change...i took out r1, 1k and replaced it with a 10k trimmer, so i could play with the delay time a little..1k sometimes seemed just a little too little...and this way, it can do a nice double, with the trimmer cranked...
i like it right about 3.43 k the best, fwiw
Thanks Jimi - I've just ordered 10 more PT2399's.
Hopefully one of them fixes my problem :)
Good idea about the trim-pot too, I might give it a go once it's all working.
if you move that trim pot and there is ANY wiggle, the pt2399 is working...most of 'em will, but some seem to start self oscillating either above my hearing range, or motorboating..giving em a little tweak seems to help.
i don't know why it doesn't self-modulate sometimes...it seems almost like the attack of the guitar is what gives it wiggle. but tweaking the trimmer you should be able to get enough time to get it noticeable ...really kinda subtle. i still can't get it to sound as good as anchovie's demo...thinking of trying to mod the voltage divider for a little more delayed signal, but i don't think that's the problem...getting it to modulate is, at least for me.
when it's working, it sounds almost like a boss dimension c...you almost can't tell it's on, but switch it off and you know it's not there. slight volume drop too, but i'm gonna try adding a simple transistor boost after it to see if i can get it up to unity or slightly above.
My new PT2399's have arrived.
I just ripped one out of the package and chucked it into the socket... and it worked perfectly!
Thanks for you help - now it's modding time :)
Quote from: pinkjimiphoton on February 22, 2012, 12:58:17 PM
i'm gonna try adding a simple transistor boost after it to see if i can get it up to unity or slightly above.
Much easier to do what Pat did and change the 680k for a 330k - increases the gain of the first stage. Or you could put a 1M trimpot there and tweak to taste.
Quote from: mwynwood on March 01, 2012, 12:43:14 AM
My new PT2399's have arrived.
I just ripped one out of the package and chucked it into the socket... and it worked perfectly!
Thanks for you help - now it's modding time :)
This is excellent news!
tried using a 430k resistor in place of the 680k...made it seem to distort too much.
went thru 20 pt2399's. 4 work in the circuit, but all 4 mess up after a couple power ups. what a drag. gonna try the chips in my delay, and see if they function there.
noticed the reg gets extremely hot with some of the chips, assuming that means them chips are shorted.
when all was said and done, used a 30k trimmer for r 11 and 12, found a couple "sweet spots"...and replaced the 1k resistor (r1) with a 10k trimmer.
when it WORKS, it works great. still can't figure why it acts so weird...
wondering if it's oscillating above my hearing range, may stick it on my scope later and see if i can see anything.
the bitch is, when it works, it sounds great..but sometimes it just doesn't seem to matter. powering up repeatedly works sometimes, sometimes adjusting the "lush" control (which now works...go figure) does it too.
gonna keep playing with it, do ya think adding the npn and stuff to pin 6 is worth trying? will the trimmer still work between pins 4 and 6? it's nice to dial in a "sweet spot" there...
thanks!
Hello,
here's my Layout based on the schematic from page 1, I have not build it yet, so it is not verified...
...but I am very sure that it is ok and will work, I compared it to the stripboard-layout and also to the schematic ;)
http://img861.imageshack.us/img861/8206/onechipchorus.jpg?http://imageshack.us/
I hope that I soon will have the time to build it!
(http://img861.imageshack.us/img861/8206/onechipchorus.jpg?http://imageshack.us/)
Greetings from Germany
Magnus
Here it is all boxed up in a "blemished" enclosure from Mammoth I got for about $5! :icon_biggrin:
I swapped R3 from 680k to a 470k to bring the volume of the effect up to match the bypassed volume.
I swapped C12 from 100nF down to 10nF to brighten up the effect tone up to match the bypassed sound.
(https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-ash4/418038_10151370077350008_789025007_23155816_944692775_n.jpg)
Thanks to everyone for their help!
cool, nice build....any clips? :icon_cool:
Just recorded a short sound clip: http://soundcloud.com/mwynwood/my-lush-chorus-pedal (http://soundcloud.com/mwynwood/my-lush-chorus-pedal)
nice one marcus: sounds really nice, i think i'd like a speed control on it, i'll have to get round to breading this for sure, cool... :icon_cool:
Thanks man :icon_biggrin:
A speed control would be great - even if it were just an internal trimpot.
Let me know how you go!
hmmm, got this on breadboard at the mo...not working yet.
i'm using this schematic
http://www.diystompboxes.com/smfforum/index.php?topic=92872.msg796348#msg796348
...one dumb question though, where do the vr's go...to the lush pot?..
going by magnus's layout?....
hmmmm...redone the breadboard a cople of times..., got clean sound , no chorusing... :'(
bumpy!!! :)
:ok so the vr's go to pin 2 of the pt2399...cheers james,. ;)
They join together, so the Vr point on the right half of the schematic goes to pin 2.
cheers man.!!!.. ;)
Definitely like the sound of this - can anyone sort a speed control though ?
I think that's what's missing to make this perfect.
Dan
Based on schematics for standalone Phase Shift Oscillators, the Lushness control should be the speed control. But using one of the PT2399 op-amps for the LFO forces the use of the chip's voltage reference as the ground point for the oscillator and makes wacky stuff happen. There is a subtle change in speed, and also a change in LFO shape, and it's all completely unplanned and unpredictable!
If you want full LFO control, you'll need at least a Two Chip Chorus.
^ right, i got it going yesterday, and yes, i got lush chorus ( think walking on the moon /police) i tried different values for the 22k..i lowered that and got a much more warbled chorus...
but the chip locks up now and then ::)...i also moved the connection to the 10k / post 10k as taylor previously suggested, and got that pitchy vibrato too... :icon_cool:
then i conected a pot to pin 6 and messed around with delay....great fun, but i too would have liked a speed control, so i guess its knock up an lfo, and sort out that lock up fix...
thanks for the cool project james, its the first time ive breaded a pt2399, and messed around with it, its a blast....nice one!.... i'll try ricks little angel later too as it has lfo and see how that goes...i'd like to get the vibrato mod on it now too...... :icon_cool:
cheers guys. :icon_cool:
Here's my verified layout for OCC. I've been enjoying the challenge of squeezing stuff onto those little 25x9 boards. This is the squeeziest and breaks a couple of my rules (some resistors standing up, one diagonal resistor!, etc.), but I'm kinda pleased I managed it. Though no doubt Adriano could manage it on something half the size! ;)
(http://www.bouron.org.uk/marc/OCCDIY.GIF)
Note four regular links in yellow, and one rule-breaking large link feeding Vr to pin 2. Watch out for breaks underneath the horizontal caps and resistors.
And here's the finished article:
(http://www.bouron.org.uk/marc/occ089.JPG)
A couple of the elecs look a bit drunk - I think they've been squished a bit, hanging around waiting for a home. And those two mahoosive greenies were not exactly what I had in mind...
Anyroad, now working on putting it in a box (sorry to disappoint - it's not going in a 1590A!).
Quote from: bluebunny on March 27, 2012, 04:21:06 PM
... (some resistors standing up, one diagonal resistor!, etc.)...
(http://www.bouron.org.uk/marc/OCCDIY.GIF)
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.
@marc: any problems with pt2399 lockup...?
Quote from: deadastronaut on March 28, 2012, 04:27:29 AM
@marc: any problems with pt2399 lockup...?
Nope, not so far...
cool. when i breaded this and the la chorus, i found this to have more depth....might have to re-bread this again...cheers. ;)
Quote from: Perrow on March 27, 2012, 05:15:19 PM
Quote from: bluebunny on March 27, 2012, 04:21:06 PM
... (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... :icon_biggrin: 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!
Quote from: bluebunny on March 28, 2012, 01:45:13 PM
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 :icon_eek:
and I've spent more time making it than playing the guitar :)
Quote from: Perrow on March 28, 2012, 02:51:07 PM
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 :icon_eek:
Quote from: bancika on March 28, 2012, 05:16:23 PM
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... ;)
Quote from: bancika on March 28, 2012, 05:16:23 PM
and I've spent more time making it than playing the guitar :)
thank @#$% for that!....its a great prog!. ;)
OK, trying to understand the PT2399 here. If I want to make this with a wet signal only, do I disconnect pin 15?
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.
Quote from: anchovie on April 03, 2012, 04:59:44 AM
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?
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! :D
Thanks! I'll give it a try. Very cool project! Thanks so much for sharing.
Quote from: bluebunny on March 28, 2012, 08:19:51 AM
Quote from: deadastronaut on March 28, 2012, 04:27:29 AM
@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?
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.
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...
Quote from: pinkjimiphoton on July 10, 2012, 01:34:33 PM
the damaged ones tho, i guess you COULD use the opamps in them to make fuzzes or something.
LOL! :D
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!
Quote from: pinkjimiphoton on July 10, 2012, 04:12:57 PM
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.
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!
(http://i898.photobucket.com/albums/ac182/Scruffie_Crow/OneChipChorusSS-1.gif?t=1311780102)
try 470 ;D
Install a trimpot. Season to taste.
dave! good call bro ;)
Quote from: oldschoolanalog on July 19, 2012, 10:16:31 PM
Install a trimpot. Season to taste.
You mean a voltage divider trimpot, or in place of that 330k resistor?
Trimpot set up as a variable resistor in place of the 330k resistor.
I have a quick newbie question for reading the circuit: Does the "Vr" get connected to the +9V?
yes.
Quote from: pinkjimiphoton on July 24, 2012, 01:30:05 PMyes.
sorry jimi, not familiar with this circuit, but doesn't vr normally refer to reference voltage, usually 4.5v in 9v pedals?
*apologies if i'm wrong - just don't wanna lead a noob astray*
http://www.datasheetcatalog.org/datasheet/PrincetonTechnologyCorporation/mXyzsyzt.pdf (http://www.datasheetcatalog.org/datasheet/PrincetonTechnologyCorporation/mXyzsyzt.pdf)
i thought that was vb that was the half voltage arti...
i may be wrong, and probably am, knowing me.
looking at the vero on page one of this thread, r8 and r9 connect via a jumper to 9v b+
i thought i may have been mistaken, so i went back to look to be sure...
if that's a mistake on the vero, it may explain why i can't get my build to work....which is weird, cuz i DID get it to work like a 1 slap delay.
please check page one of the thread, i really have a hard time trusting my eyes lately.
EDIT: i just checked the vero and the schematic, and it's indeed referencing the full 9v as shown on the vero, at least...
(http://i55.tinypic.com/oaam41.gif)
cool. as i said, i'm not familiar with the circuit - i just saw the question 'should i connect vr to 9v' and responded. i'll try and keep my noob mouth shut in future. apologies for any confusion, folks.
no, bro, please don't ... i believe you are actually right, the confusion may be in the nomenclature used...
pretty sure vr is voltage reference, and vb is bias voltage...
hopefully one of the rockstar guys who know what's what will be able to set us ALL straight.
Well I actually found a successful solution that is different from what both of you two were saying haha. I read in one of the earlier posts that you are just supposed to connect the two Vr points together, not connect them to the 9v or anywhere else. I did this and it worked like a charm. I guess I'm a little confused as many of the layouts made by others depict this done otherwise but hey, it works. I'm not gonna question it.
I haven't played with this in awhile and dug it out (and my unpopulated PCB). Jeezzuss!!! Between ONE build of this and ONE build of the Harmonic Energizer, I used a total of 15x 10uF electros. :o
Hi everyone!!!
Anybody try the Mad bean layout to see if it works with the extra knob?
Joel
...and after over a year since designing it, I finally built my own vero layout! Changed R3 to 470k.
Many thanks to all who verified it!
Ok orders the part I need with enough chips to try a few.
Will keep you guys posted. ^_^
Ok so I made the circuit... Really messed up the board by making the cuts as if I was facing the strips... basically had to flip the circuit around not a big deal...
what is a big deal is, I wired my power wrong and got the whole tip negative thing wrong... just got confused on which lug in the dc jack was tip and what not....
Anyway... I plunged it in like this and got no sound. The I realized my mistake and flipped things around, and it now passes sound... but there are some problems...
Getting the pulsing sound that repeats at a steady rate.... Think this means the LFO is working.... problem is I'm not really hearing any chorus... it is almost like I have my normal sound with an added buzz plus the LFO pulsing thing... I've tried another chip and get the same results so now I just need to know...
Did I screw anything up with the Frist power inversion and if not what is the problem.
First thing to do would be to measure voltages on all the pins of the chip and regulator.
Regulator
p1 16+
p2 0
p3 4.8
Chip (I don't know the numbering so I'm doing it as if you count down one side of the chip then the other... starting from the side with the dot on it as pin 1.)
1 4.87
2 2.22 to 2.68
3 0
4 0.25
5 1.3
6 2.26 (jumps around a bit)
7 2.26 (jumps around a bit)
8 2.26 (jumps around a bit)
9 2.30 (jumps around a bit)
10 3
11 .19 to 4.80
12 2.38 (jumps around a bit)
13 2.80 (jumps around a bit) (Modulated single present.)
14 2.40 (jumps around a bit)
15 2.4 to 2.6
16 2 to 3
Let me start by saying that since the circuit pass signal without being plunged in... that means that the dry signal line is working....
I probed all pins and from 13 I'm getting a modulated signal. However the sound is rather harsh and there is some background hiss and crackle. Turning VR1 does effect the signal I'm getting from here but over all it seems to have no bass and sounds thin and bad...
However I hear no effect when it is plugged in and I take my sound from (B20).
I think what I'm hearing from pin 13 is the signal 100% wet, and the hiss/crackle is the 2.8vDC that is on that pin.
So it would seem the regulator and the chip are working, The dry signal line is working, but that something is wrong with the wet signal line... so starting from (H10-H20)... i need to check every component that carries the wet signal to the output jack and see what the problem is....
or is there something off in my voltage reading I provided???
Quote from: Ark Angel HFB on October 16, 2012, 09:04:52 PM
Chip (I don't know the numbering so I'm doing it as if you count down one side of the chip then the other... starting from the side with the dot on it as pin 1.)
(http://www.amiga-stuff.com/hardware/images/DIP-numbering.gif)
Chip Reading now that I know the pin out... Thank you btw.
1: 4.87+
2: 2.22+ to 2.68+
3: 0
4: 0.25+
5: 1.3+
6: 2.26+ (jumps around a bit)
7: 2.26+ (jumps around a bit)
8: 2.26+ (jumps around a bit)
16: 2.30+ (jumps around a bit)
15: 3+
14: 0.19+ to 4.80+
13: 2.38+ (jumps around a bit)
12: 2.80+ (jumps around a bit) (Modulated single present.)
11: 2.40+ (jumps around a bit)
10: 2.4+ to 2.6+
9: 2+ to 3+
Ok I got mine working correctly...
Guess it helps when you don't forget to put R13 on the board... >_>
Honestly I love the sound but it seems to freeze up if left on and I don't play for a while... will have to see if I can fix this or it still isn't useful...
Side note... the sound is rather nice and very organic sounding... it doesn't sound digital or bad in anyway... a real winning pedal... if I can fix the freeze up problem...
How would I go about brightening this circuit up without making it too thin... or the volume be below unity?
It sounds really nice but it is a a bit too dark...
I Ideas?
I was thinking maybe another stage with a simple boost circuit? or what?
you'll need some sort of booster circuit, unless you maybe raise the gain of one of the opamp stages...may be tricky, as it could distort.
try smaller input cap, to make it brighter..
Yeah, lowering the value of the input cap might help if you want to shave the low end off both the wet and dry sounds. I wouldn't bother making a booster - there isn't a great deal of headroom in a PT2399 so you'd be better off replacing R3 with a 1M trimpot and setting that to the best level.
Whilst lowering the input cap will reduce the bass, the heavy filtering that most PT2399s use could still reduce brightness. Try lower values for C12 and find the treble/hiss balance on the wet signal that works best for you.
I had trouble with the LFO locking up when the variable resistance was too low. You could try adding a few more Kohms in series with R8.
what about this...
Dropping R11&12(The resistors that determine mix) down to 1k. Dropping C13 down to 1uf or even 1.1uf. Then and raising R13 up a good bit...
wouldn't the over all effect be...
R13 Increased = More resistance to ground so increased volume.
R11&12 lowered the same amount = Same balance but less resistance so increased volume. (Now we have a hotter than unity signal that is bass heavy)
C13 Lowered = Bass is cut away leaving a brighter over all sound with the same 50:50 blend of dry and wet signal.
If this all works outs... then simple messing with the value of R13 and R11&12 till you get the volume back to close to unity but with less bass...
OR... add a (R14 between signal and the out and a just values till it is right.)
Give it a try! This is one of the circuits that revealed that not all 2399s are created equal, so by that fact it's a tinkerer's playground!
is the 47pf cap a critical part of this circuit? What other values can I subtitute for that?
Quote from: jogina111 on December 12, 2012, 11:31:55 PM
is the 47pf cap a critical part of this circuit? What other values can I subtitute for that?
http://www.taydaelectronics.com/
Just order some buddy... shipping is cheap. ^_^
On a side note... could we possibly take the lock up fix from the "Little Angel" chorus and apply it to this?
Hi, everyone!
I am new to this forum, but I must admit I enjoy it a lot, though reading through 46 pages of "Little Angel" could be somewhat braindamaging ;D
The reason I am posting here is something I've already mentioned in Merlin Blencowe's thread about pt2399-based reverb, but as for me, the issue is
serious enough to be repeated here, and anywhere the PT2399 is ever mentioned, as to become a part of PT2399 FAQ.
There are literally hundreds of posts complaining about non-working PT2399, strange problems, lockups etc. Especially interesting are the posts
mentioning some PT's pulled out from working delay circuits are simply not working in some others...why? Gonna tell you!
When I first realized the problem it hit me so much by it's obviousness, that I simply DO NOT UNDERSTAND, how can such a basic issue pass in front
of so many eyes without being spotted? Also, how could such genius designers simply ignore A BASIC RULE OF MIXED-MODE CIRCUIT design while designing
their PT-based circuits???
The PT2399 IS a mixed-mode circuit, meaning it has an analog, as well as a digital part inside. Either part has to get POWER. And while the power rails
of these parts are tied together within the chip, their GROUNDS are split apart and represented by pins 3 and 4 respectively. Now here comes the
part of wonder - WHY DO YOU GUYS IGNORE THIS??? Pin 4, which clearly seems to be unconnected in EVERY PROBLEMATIC CIRCUIT - represents the
digital ground of the IC. The PT2399 datasheet clearly states this pin MUST be also connected to the ground (in real mixed-mode circuits I used to design
this is done via a ferrite-bead inductor or a small resistance). Guess what happens, if you leave it unconnected? Bingo! All the strange problems you guys get with those "wrong
batches of IC's" etc.etc. It's because you leave the digital part of the circuit WITHOUT POWER (or getting some power through parasitic ways causing strange behavior)
I just can't emphasize enough - PIN 4 MUST BE ALWAYS CONNECTED TO THE GROUND - and voila: any PT2399 starts working!!
Try checking those delay circuits you pull your working (but otherwise misbehaving) PT's out, and you'll find the reason I'm talking about - those circuits surely
have pin 4 grounded! Everybody - please read and memorize this forever!
Now, coming back to the mysteries of PT2399. It is proven now (I have on my bench some IC's of either kind), that older batches of PT's had their grounds connected WITHIN
the IC's with a smaller resistance (about 15 ohms), so those older circuits DO WORK without grounding the DGND (pin 4), while some newer ones DO NOT HAVE this done internally. Either kind IS okay since the datasheet REQUIREMENTS are fulfilled. Circuits that work with pin 4 unconnected are an exception rather than a rule, and this exception
shouldn't be ever exploited, being done the correct way.
I sincerely hope that this post will help to bring clarity into the hassle around PT2399 misbehavior and will also serve well for all future PT2399 experimenters.
Please, all those ever had problems with their PT2399's or particular circuits - try applying this simple fix - I think the majority of problems are going to get resolved.
Wishing everyone all the best and many-many successes in our beloved hobby!
Long live DIY! ;D
Many problems with PT2399 circuits do stem from bad ICs. I've experimented for hours with grounding schemes and many batches of ICs before concluding that there are numerous substandard ICs out there that won't work properly, no matter what circuit they're in and no matter how pins 3 & 4 are configured.
My Repote2 delays work perfectly and pin 4 is grounded. Some ICs instantly lock up and get hot. Not just odd ones, but every one from a given batch. Others are noisy beyond use. The ones that work fine are a mixture of old and new production. Other builders have found the same. So what are we all missing here in circuits with pin 4 grounded and PTs where some work, some dont?
Well, perhaps some IC's out are bad indeed, coming from defective batches - I can't state surely. I had about 3 dozens of these IC's going through my hands, bought at different time from different suppliers (chinese e-bay sellers, usually the cheapest ones) - and never met one really defective, apart from the only difference mentioned above. This difference can be easily spotted by measuring resistance between pins 3 and 4: if there's no 10-15 ohm resistance between them, the IC will definitely not work with pin 4 left unconnected, and very likely to work fine with both pins (3&4) grounded.
Now, what we are definitely missing _here_ is pin 4 grounded - that will 100% cause problems with some of the IC's. Of course, thet's not a universal cure if the particular IC is faulty (which case personally I never met).
Also probably worth adding here, that for those PT2399's having no internal connection between grounds, might be a good idea to connect pins 3 and 4 through a small 10-15 ohm resistance or(/and) a smaller inductor for a couple of microhenries. This is a standard practice in mixed-mode circuit designs and significantly reduces the noise injected by the digital circuitry into the analog power rail.
I am going also to try powering the chips from a PS built using negative-rail regulators (7905) with the positive rail serving as their common virtual ground and feed the DGND and AGND separately.
The 15 ohm resistor reminds me of the same value component used to seperate the signal ground from chassis ground in some Fender products (notably the reissue standalone reverb). It effectively elevates the signal ground by the voltage drop across the resistor, eliminating grounding noise.
If you short this resistor out these reverbs make a lot more noise.
In seperating the digital and analogue grounds in the PT2399, would it be a better situation to ground the digital side (pin 4) and leave the analogue ground (pin 3) elevated on its 15 ohm resistor?
I've just measured the built-in resistor - actually it's exactly 10 ohm, not 15, but that doesn't matter too much.
M.B. >> If you short this resistor out these reverbs make a lot more noise.
Indeed, I have tried this on a breadboard - adding this 10 ohm externally between pins 3&4 seem to affect the noise floor somewhat.
I think that the initial release of the chip included this resistor, but in the latter revision the designers simply decided to give
some more flexibility to the consumer by being able to choose way they want to connect grounds - that's why these IC's don't have their grounds
connected internally anymore.
M.B. >> In seperating the digital and analogue grounds in the PT2399, would it be a better situation to ground the digital side (pin 4) and leave the analogue ground (pin 3) elevated on its 15 ohm resistor?
I don't think so - because it's exactly the analogue circuitry being affected by the noise, therefore it's recommended to keep it's ground potential as close to zero, as possible. In the Fender amps you've mentioned, the chassis ground (the chassis itself works as an antenna) represents the same kind of noise source, as the digital circuitry in our case.
Thus, by adding the 15 ohm resistance, I would it's say the chassis potential being elevated above the signal ground - but considering there's no current flow, we don't have potential elevation, but do have interference attenuation. By elevating the analogue ground above the signal ground we would artificially achieve the effect of the ground
loop - something that designers try to avoid all the time.
But, further developing your idea I came to another one: even better noise attenuation could be achieved by separately bypassing the digital and analogue ground pins to the positive rail, prior to connecting them together with a 10 ohm resistance.
(http://s1329.photobucket.com/user/ViktOr_Molnar/media/PT2399-grounding_zps705047e6.gif.html)
(http://i1329.photobucket.com/albums/w553/ViktOr_Molnar/PT2399-grounding_zps705047e6.gif) (http://s1329.photobucket.com/user/ViktOr_Molnar/media/PT2399-grounding_zps705047e6.gif.html)
This is how I mean
Along the day I was playing around with these circuits.
Built the one by merlinb, but didn't like the effect - it sounds more like a phaser. Threw into disassembly queue.
Went back to anchovie's original design but with the ground fix (from previous message) and dry/wet mix pot implemented,
and Wow! All the noises gone! Sounds fantastic, doesn't have too much versatility, but also doesn't seem to require that.
Really, really grateful to anchovie!
Spent about 2 hours to design, etch, drill and populate a PCB. If anyone is interested in the layout - just give me a shout...
(http://i1329.photobucket.com/albums/w553/ViktOr_Molnar/Anchovie_Chorus_zps2a381410.jpg) (http://s1329.photobucket.com/user/ViktOr_Molnar/media/Anchovie_Chorus_zps2a381410.jpg.html)
Think we'd all be interested - go a head and posti it!
Okay then :) Here it is. Simple as sh!t :)
The board size is 41x33mm. The layout presented from see-through top view, so it doesn't need to be mirrored
for printing. It also has one wire bridge beneath the chip (didn't want to mess with too thin traces to keep the
layout DIY-friendly) - make sure you install this before the IC socket.
(http://i1329.photobucket.com/albums/w553/ViktOr_Molnar/OneChipChorus_zps9b17299b.jpg) (http://s1329.photobucket.com/user/ViktOr_Molnar/media/OneChipChorus_zps9b17299b.jpg.html)
Parts placement. The 10 ohm resistor is necessary only if your particular PT2399 doesn't have it built in - a good
idea would be to check it between pins 3 and 4 before installing the chip. But in either case it wouldn't harm :)
(http://i1329.photobucket.com/albums/w553/ViktOr_Molnar/SimplePT2399Choruslay_zpsb6f341a9.jpg) (http://s1329.photobucket.com/user/ViktOr_Molnar/media/SimplePT2399Choruslay_zpsb6f341a9.jpg.html)
Layout for printing, 300 DPI resolution. Make sure you don't mirror it.
Oh, yes, and it IS verified (i've got mine working).
Just for curiosity - built also the Little Angel, and I must state, that despite higher complexity it sounds worse
(okay, perhaps worse is a too strong word - but different, and definitely less chorus-y),
even with all mods applied and increased depth control.
So, just like always - the simpler is the better :) Thumbs up anchovie! ;D
I just love performing Metallica's "Sanitarium", or Dream Theater's "Pull me under" intro through this little gem!!!
I going to give this another shot tomorrow... will see how it turns out.
Thought I'd drop an update.
I built this again today with some tweaks.
I removed R11 and R12, in order to do the mix pot option. I used a 10K lin pot, which brought the volume up a good bit above unity... Will try bringing the volume to perfect unity by ether lowering R13, or adding an R14 of about 2.2k to the output of the mix pot.
Next I lowered C13 from 10uF to 1uF. The sound had been a tad on the low side for me and the reduction of some of the bass, coupled with an overall volume increase really helped the pedal sparkle nicely.
Lastly I added 10 ohm resistor from ground to pin 4, as talked about above on this page. I tested a pt2399 that had been locking up previously and guess what... no lock up. Played for a solid hour and greatly enjoyed the sound and options the circuit was giving. I even left it on and alone for another 30 minutes just to check and see if it might lock up... never did.
Over all I'm really very happy. I'm going to try and take some time in the next day or so to make a graphic for it and try my hand at some water slide decal'ing... Will post pics... thanks for this great circuit.
I finished my build today. Wonderful chorus!
Congratulations anchovie.
Quote from: merlinb on August 03, 2011, 11:03:32 AM
Here's another take on the one chip chorus. This one has deeper modulation, so it generates a very thick warble, more like the deep settings on a LA. It also has an improved latch-up fix that may be useful for other projects.
(http://i81.photobucket.com/albums/j207/merlinblencowe/OneChipChorus.jpg)
is there something wrong with this schematics?can anyone tell me what is that?
Is this a quiz or are you not interested in reading the thread?
my english is bad..i'm not sure i understand what are they discussed about..that's why i'm asking
and i'm a newbie here :icon_frown:
So because you are new and don't speak English well you would like us to test and report on a schematic you dragged out of the thread prior to you doing so?
Did you have a problem with the circuit or not?
I think he just wants to know if that schematic is good to use for a build.. If you don't speak/read english well it's hard to make out which schematic in a thread with a couple of different schematics is good to go.. so:
I'd say, yes that schematic is fine, it's by a forum member that is know to produce good schematics (the U-boat comes to mind)
:-*
Quote from: ~arph on July 08, 2013, 03:13:47 AM
I think he just wants to know if that schematic is good to use for a build.. If you don't speak/read english well it's hard to make out which schematic in a thread with a couple of different schematics is good to go.. so:
I'd say, yes that schematic is fine, it's by a forum member that is know to produce good schematics (the U-boat comes to mind)
:-*
yes,this is what i mean..thanks :)
With respects to the above schematic...
Shouldn't there be some kind of post-regulator power decoupling/filtering?
Maybe a 10uF from +5VDC to ground directly after the regulator ;D
EDIT: NEVERMIND... I see there is a 10uF right after the 100K resistor :icon_redface:
EDIT2: Should that be a 100K resistor? Seems like it should only be about 100 ohm ???
Yes i think that is fine. There is a 47uF to ground right after the regulator. The 100k is part of the anti latch circuit.
Quote from: ~arph on July 08, 2013, 09:50:52 AM
Yes i think that is fine. There is a 47uF to ground right after the regulator. The 100k is part of the anti latch circuit.
Missed that one :icon_redface:
Thanks for the correction! ;)
Hi,how to get rid of the loud popping on anchovie's circuit? i placed this after an OD and before a delay.1M at the input to ground and 100k at the output to ground and still pop.
Read through the forums, there is a pop-reduction thread going on RIGHT NOW OVER THERE ---->
Quote from: mistahead on July 09, 2013, 07:59:35 PM
Read through the forums, there is a pop-reduction thread going on RIGHT NOW OVER THERE ---->
?
Quote from: fretzburner on July 09, 2013, 09:52:42 PM
Quote from: mistahead on July 09, 2013, 07:59:35 PM
Read through the forums, there is a pop-reduction thread going on RIGHT NOW OVER THERE ---->
?
What he means is that popping is a common problem with a lot of circuits, and there is a much larger thread on the forums talking about it... this circuit doesn't really pop for me though so it may be a LED powering on thing... if that is the case look into the fixes... I fixed mine. Do a little leg work you will find the solution easy.
What he means is that popping is a common problem with a lot of circuits, and there is a much larger thread on the forums talking about it... this circuit doesn't really pop for me though so it may be a LED powering on thing... if that is the case look into the fixes... I fixed mine. Do a little leg work you will find the solution easy.
[/quote]
Thanks Ark, now this is a real answer.will try to disconnect the LED and check if popping be eliminated or lessened.Very small circuit but great sound.
Quote from: fretzburner on July 10, 2013, 08:13:06 PM
Thanks Ark, now this is a real answer.will try to disconnect the LED and check if popping be eliminated or lessened.Very small circuit but great sound.
Fixing the Led popping btw is very simple... do a few search for solution but if you do come up empty message me and I link you where you need to be...
If you find out the solution on your own you will never forget it and it will make you a better builder for it. ^_^
Same problem with pop sound, maybe will use other means like buffer it or use fet switching with this circuit.my other builds like dirt pedals were okay,only small pop and is tolerable.
I built Viktor's version and, IMHO, the chorus sounds way better with the following mods, some of which have been taken from other members' suggestions.
Two of the 10uF capacitors were causing the circuit to oscilate heavily when the power supply was connected.
I would like to point out that these are merely suggestions.
(http://imageshack.us/a/img89/3356/czmd.jpg)
Quote from: adielricci on July 13, 2013, 11:16:37 PM
I built Viktor's version and, IMHO, the chorus sounds way better
Define better?
I'm assuming you mean that the chorus is a bit brighter than the first version...
Quote from: Ark Angel HFB on July 14, 2013, 11:52:14 AM
Quote from: adielricci on July 13, 2013, 11:16:37 PM
I built Viktor's version and, IMHO, the chorus sounds way better
Define better?
I'm assuming you mean that the chorus is a bit brighter than the first version...
Sorry, my bad. By "IMHO" I supposed everybody would understand that it was a subjective point of view, I beg your forgiveness for being so careless.
I meant it lacked brightness and the modified sound was somewhat below the level of the bypassed signal. Was the oscilation part clear to you, Ark Angel HFB, or do I have to be more specific?
Stating it was in your opinion doesn't really attach any adjectives to what you observed...
Thanks for clearing that up - your perception is in line with a lot of the folks here, that said the slightly murky/less than unity sound can be exploited with a few tricks... should you want that sort of outcome (which most don't seem to).
Quote from: mistahead on July 14, 2013, 07:53:25 PM
Stating it was in your opinion doesn't really attach any adjectives to what you observed...
You're right. I will be more careful in the future.
Quote from: adielricci on July 14, 2013, 07:28:32 PM
Sorry, my bad. By "IMHO" I supposed everybody would understand that it was a subjective point of view, I beg your forgiveness for being so careless.
I meant it lacked brightness and the modified sound was somewhat below the level of the bypassed signal. Was the oscilation part clear to you, Ark Angel HFB, or do I have to be more specific?
woo woo take a breath buddy. My comment on defining "Better" was asking you to explaining what result you got. "Better" IS really subjective and could mean anything since no one on here knows you. For example maybe you play jazz and like darker tones with really muted highs... your "Better" might mean a sound with less highs in the signal because you like that.
It is like me telling you that I recently changed the tires on my car and now it is "better". Do I mean the new tires are more slick because I like to drift corners, or do they have more grip and a built in fast air release for off road'in? You have no clue because you don't know what my "Better" is... so "Better" doesn't tell you a damn thing.
The oscillation part was clear... because you actually stated the result.
I hope the above "Better" explained why I asked you what you meant.
(http://i73.photobucket.com/albums/i215/Ark-Angel-H-F-B/cm_punk_drop_the_mic_by_paynexkiller-d46psqv_zps44ea9ae2.gif) (http://s73.photobucket.com/user/Ark-Angel-H-F-B/media/cm_punk_drop_the_mic_by_paynexkiller-d46psqv_zps44ea9ae2.gif.html)
Perfectly, Ark Angel HFB. Points taken. :)
Interestingly, the popping was also reduced (but still there) after those modifications.
Here's my version of the One Chip Chorus:
(http://s20.postimg.org/3wdr4ayfd/OCC.jpg) (http://postimg.org/image/3wdr4ayfd/)
It's pretty similar the stock OCC, but I've made a few changes based on my readings here (http://sound.westhost.com/project26a.htm) (an excellent article, anyone experimenting with these chips should read it) and my breadboard experiments. The one problem I have with the stock OCC is that the high frequency response is, quite frankly, terrible. Improving this was one of my goals, and was achieved by putting the 47pF capacitor across the 470k resistor at the input, and removing the 100nF capacitor from the delay output to vr (neither of these changes seemed to affect noise levels, which was nice).
My other major goal was fixing the lockup (I ocassionally had chips lock up on me with the stock circuit, even when I had pins 3 & 4 connected). I tried the lockup fix from the article mentioned above using a BC337 transistor. The delay time was noticeably shorter (shorter than with pin 5 grounded :o), so I measured the resistance from pin 5 to ground, and with my multimeter probes around one way, I got open circuit, and when I reversed them, I measured around -3k!!! I'd heard about some transistors that do this, and had always wanted to try it out in a PT2399 circuit to see if it was possible to get a short enough delay for flanging.
This circuit does have a hint of flanging in there, but it's not strong enough to call it a flanger yet... I'll leave that to someone else. I had read however, that there is more feedback in flangers than choruses, so I tried adding some. It didn't make it sound any more like a flanger, but it did seem the whole thing sound a lot more natural, so I left it in. I also changed a few of the 10uF capacitors to smaller ones to reduce the physical size.
In short, this is a brighter chorus with shorter delay times, giving a slight flanger sound as well as ordinary chorus.
Enjoy,
Edward
Quote from: Earthscum on October 11, 2011, 09:11:52 PM
Hey all, before I forget... the micro-sized layout I promised several pages ago, lol. 1.2" x 1.5", scaled for 300 DPI Print. You'll need to mirror the image for toner transfer etching, I have it set up for silk screen transparencies.
I have the ground plane extending under the chip in an effort to isolate the power side from the signal side (at least I think that's what my idea was). Also note either resistors OR trimpot for the output. Lush control is set up as a trimpot in case you want to make a "No-Knob OC Chorus" NoKnOCChor? :icon_rolleyes:
Anyhoo...
(http://img442.imageshack.us/img442/7240/anchovieocc.gif)
this layout tested this? some modification?
The 78L05 needs to have its middle leg grounded, so I'd say it's probably not been verified.
QuoteMy other major goal was fixing the lockup (I ocassionally had chips lock up on me with the stock circuit, even when I had pins 3 & 4 connected). I tried the lockup fix from the article mentioned above using a BC337 transistor. The delay time was noticeably shorter (shorter than with pin 5 grounded Shocked), so I measured the resistance from pin 5 to ground, and with my multimeter probes around one way, I got open circuit, and when I reversed them, I measured around -3k!!! I'd heard about some transistors that do this, and had always wanted to try it out in a PT2399 circuit to see if it was possible to get a short enough delay for flanging.
Thats is interesting! Have you been able somehow calculate the delay time? I could see this be interesting for some applications
Quote from: knutolai on October 24, 2013, 06:07:15 PM
QuoteMy other major goal was fixing the lockup (I ocassionally had chips lock up on me with the stock circuit, even when I had pins 3 & 4 connected). I tried the lockup fix from the article mentioned above using a BC337 transistor. The delay time was noticeably shorter (shorter than with pin 5 grounded Shocked), so I measured the resistance from pin 5 to ground, and with my multimeter probes around one way, I got open circuit, and when I reversed them, I measured around -3k!!! I'd heard about some transistors that do this, and had always wanted to try it out in a PT2399 circuit to see if it was possible to get a short enough delay for flanging.
Thats is interesting! Have you been able somehow calculate the delay time? I could see this be interesting for some applications
Never mind about that, it was almost definitely the voltage from the chip stuffing up the resistance measurement
Would it be possible to control the mod-depth by adding a voltage divider (pot) between the "MOD" label and pin 2 of the chip?
Whats the advantage of modulating pin 2 opposed to pin 4 (as on the echo base delay)?
EDIT: Never mind, looking at the Little Angel Chorus pretty much answered the question
fwiw, i got this in the mail the other day as a possible "fix" for the lockup issue...
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
Fun project! I always love it when I have all the parts on hand before I even see a project. :icon_biggrin:
Nice to see this still gets a look-in once in a while! :)
The main aim I had with this was a proof-of-concept that you could get a LFO running in the PT2399 without any extra ICs. By all means tweak the filters to taste - the only judge of right and wrong is your ears! For me personally the frequency response of the original was fine, but that's probably because I tune down to C and play distinctly un-jangly riffs. ;D
whatever it was set to as a result of not the cleanest solder job when I first put it together would have been nobodys taste but mine! Tons of noise followed by what you might call a faint delay after about two seconds....it basically sounded like something breaking but not nearly as loud as my clean signal....it was violent but I liked it lol
Hello,
I am working on my layout based on the schematic from the first page
but with the "ground-fix" and "mix-pot-mod" from Vikt0r and I have two questions:
What value does the mix-pot have (10k lin?) and what does it actually do?
My layout is almost finished, its as small as possible and I think it went really well ;)
Greetings
Magnus
Hello, this is my first action in this forum. I build the version 1590a of page 2, when I turn it on there is no chorus, only after making a bridge between pins 5 and 6, releasing it, appears working correctly.
Apparently starts blocked and then the bridge works properly.
Thank you
Welcome David. Shorting to pin 5 is a bit of a red herring. Sounds like the resistance at pin 6 may be too low. You might want to try two things. Try instead shorting pins 3 and 4 (thereby grounding the end of the 1K resistor); they are supposed to be connected internally by a low resistance, but some people like to short them explicitly (they are both flavours of "GND" connections). And/or check that the 1K resistor is indeed 1K and isn't itself shorted.