Zombie Chorus on Perfboard (effectslayouts modification)

[matlevo12]

Hi everyone.

I know, it's probably the hundreth topic abouth that circuit but I'm building it and would like to share something with you.

I found this layout on effecslayouts : http://effectslayouts.blogspot.com/2017/07/zombie-chorus.html
But, like some comments point out, there are some mistakes/differences between the board and ths schematic that's supposed to be based on (http://www.pisotones.com/Zombie/MBC/Z2/ZCh2.htm).
I found another good schem here at Geofex : http://www.geofex.com/PCB_layouts/Layouts/zombie.pdf
I'm going to base my comments on the geofex schem from now on.

Anyway here are the mistakes that were pointed out :
- C8 (10nf)  is missing, and there is a 10k resistor in its place (between pins 6 and 7 of the 4558)
- R14 (100k) is missing (between pins 1 and 3 of the 4558)
- R13 is 15k on geofex schem, not 10k (but some schem show a trim here between R12 and R13, to get 4.5V at Vb)
- vibe 2 (there you have to look at the pisotones schem) isn't going if the right place, it should be between R5 and R10
- some power filtering caps are missing : C11 and C12

I tried my best to copy the original perfboard schem and modify it to fix those problems, here it is :



As you can see I reorganised some things and coloured in red the parts I added/modified (I plan to put sockets there to check if it does work without them).
If someone could have a look and tell me if they think it's good that's be really cool !

Btw, next step : adapt it to MN3207 using experimentalistanonymous schem (https://www.experimentalistsanonymous.com/diy/Schematics/Chorus/Zombie%20Chorus%20MN3207%20Based.jpg)

[duck_arse]

argh - too many cross references. there appears to me to be somethings wrong around your 4558 and the 4M7 at pin 7, compared to the geofex schem. there is a pot connection for depth missing, at the very least. I might be not connecting some of your corrections, tho, and you have no marked parts designations, and that was the only corner of your layout I looked at.

[matlevo12]

Hi. Yeah sorry about all the docs and references... my bad.

Thanks a lot for the comments. For some reason diylc doesn't "auto-create pads" when I copy/paste all the components at the same time even with the option ticked, sorry about that, but here's another image of my perfboard layout with just the traces next to it, it probably will be easier to read this way.



As for what you pointed out :
- the 4M7 (R17) is at the right place, between pin6 of the 4558 and lug 2 of the speed pot
- the 3 depth pot connections are there

[duck_arse]

hmmm, no. from RG's circuit and designators, there is an R15 47k connects pin 7 one end and pin 3 AND R14 100k. I can't see anything except the C8 10nF connect to pin 7 .....

[matlevo12]

Well... Thanks a lot. That's another thing that was missing in the effectslayouts perfboard layout and that didn't appear in the comments.
Thanks for that and thanks for telling me twice.

I'll fix that when I have the time, and try to check everything again. Thanks again.

[matlevo12]

I forgot some traces... It should be better now.

[duck_arse]

oh, there was one other thing that had me confused with this thing of yours - I'd expect the TL062 was the oscillator and the 4558 was the audio/filter section. is this not correct?

[matlevo12]

Thanks again.

The 4558 is the oscillator in here.

[duck_arse]

hmmmm, yes, I see that, but I suggest it's the wrong place to use a suited for audio oppie, when you have the lowest current draw of the TL series in the audio section, with it's degraded audio performance. I'd have thought, to help avoid any possible oscillator ticking problems, the lower current consuming IC would go to the osc, is all.

[PRR]

I think the '558 has virtue when you have to work near the negative rail?

[matlevo12]

hmmmm, yes, I see that, but I suggest it's the wrong place to use a suited for audio oppie, when you have the lowest current draw of the TL series in the audio section, with it's degraded audio performance. I'd have thought, to help avoid any possible oscillator ticking problems, the lower current consuming IC would go to the osc, is all.

I think the '558 has virtue when you have to work near the negative rail?

Thanks a lot for the advice.
I'll socket everything when I try this out, some schems show two TL062 so I'll try and test !

[matlevo12]

YEAH !

Quick message out of excitement, but I just built it and it works.
Even better, I built the MN3207 version (I had 3 of them from karaoke units), and it works perfectly.

I'll post the correct layouts really soon ,there are errors in the ones I posted before, but hey, I did it

[matlevo12]

Here is the 3207 working layout (à la EffectsLayouts).

I'll post the 3007 modified version when I have the time.



I can't find a way to change the topic title and edit my older messages to erase the wrong layouts, is that normal on this forum ?

[bluebunny]

I can't find a way to change the topic title and edit my older messages to erase the wrong layouts, is that normal on this forum ?

There's a short period during which you can address typos or add extra information, but that window closes and you can no longer re-write history.  IMHO, this approach is preferable to those fora where whole chunks of history can be redacted, making threads utterly confusing.

No-one reading this thread will be confused, since you've explained what you've done as you've gone along, even if things have changed along that journey. 

[matlevo12]

There's a short period during which you can address typos or add extra information, but that window closes and you can no longer re-write history.  IMHO, this approach is preferable to those fora where whole chunks of history can be redacted, making threads utterly confusing.

No-one reading this thread will be confused, since you've explained what you've done as you've gone along, even if things have changed along that journey. 

Thanks a lot ! That does make sense

Here's the 3007 version, modified from the one on Effectslayouts (fixing / adding some stuff according to the Geofex schem), that I made before chaging it to fit a 3207.

I haven't tested this version since I don't have a 3007 chip, but since the 3207 version is working I expect it to work as well.

[StephenGiles]

I haven't been following the various Zombie Chorus threads for some years, can somebody please summarise the anti-tick mods which work?

[matlevo12]

From what I read there used to be more ticking before the alternate voltage was introcuded (http://www.pisotones.com/Zombie/MBC/Z2/ZCh2.htm) but it seem to be already fixed on any "recent" schematic.

With the schem and layout there was some light ticking with some settings when I put it in the enclosure, but the reason was my pots and switches wires being way too long and going around and above the CD4046 (and the other chips, but from what I read that's the main reason.
As soon as I shortened the wires as much as I could and kept them around the board the ticking was gone.

The pedal really sounds awesome, imo. Extreme settings and vibe/clone mode is a real fun noisy mess.

[percyhornickel]

I have an issue with the 3207 version, I have isolated pots (aluminum tape) and input jack. The chorus works very well but I get a small tick when is bypassed. The tick dissapears with other pedal in front (or any fx with a kind of buffer on it). I am thinking to solder the 4558 (LFO) ground direct to the connector gnd. I spent hours reading many posts in here...     ...I would appreciate any kind o advice.

Another thing, there is a big pop when vibe switch is engaged, everything seems to works ok but I can not find any short or something else. Is this normal?.

Thank you 

[matlevo12]

I have an issue with the 3207 version, I have isolated pots (aluminum tape) and input jack. The chorus works very well but I get a small tick when is bypassed. The tick dissapears with other pedal in front (or any fx with a kind of buffer on it). I am thinking to solder the 4558 (LFO) ground direct to the connector gnd. I spent hours reading many posts in here...     ...I would appreciate any kind o advice.

Another thing, there is a big pop when vibe switch is engaged, everything seems to works ok but I can not find any short or something else. Is this normal?.

Thank you

Hi.
I had some ticking issues (but not in bypass!), they're kind of usual for this circuit and I solved them by shortening the wires as much as possible.
Diyguitarpedals has a version of their own and explain how they so'ved it, if that helps.

[percyhornickel]

Erik Vincent from DIYGUITARPEDALS sent me a Lich King Chorus PCB and is the most quiet zombie chorus version on the market. He included ICs: 3207 BBD and 4066 PLL, I had a power supply problem at first try so I decide to build this version to ckeck..   ..I had the same issues plus the famous ticking.

I`ve read many Mark Hammer and Erik advices to reduce this and then I cut the power trace from your version and connected the LFO directly to VCC, now the thinking is almost gone and complete dissapears if there is another fx or a buffer in fron of it..  ..and that`s why now I have a "ALTOIDS BOX BUFFER" since last night

Now everything works very nice...


Percy