zombie chorus

[1878]

Hello everyone.

My next project is gonna be the Zombie Chorus. There are two firsts here.

First first: It'll be the first modulation effect I've built.
Second first: It'll be the first time I've etched my own PCB

So, what's the best layout to use ?? I'll be using a 3PDT rather than the Millenium Bypass which I've seen in some layouts. Also, I've read there are some issuses with clock noise. Any mods/suggestions on how to get rid of this ?? Feel free to throw your ideas/experiences into the hat. I like learning.

Thanks in advance.

[Mark Hammer]

While it is convenient in some ways, and I am pleased it incorporates some mods I suggested, I would recommend not using the layout by Tommyboy.  The principal reason is that it uses a single quad op-amp to provide both the audio path (2 op-amps) and the LFO (2 op-amps).  This interferes with being able to decouple the supply lines to each chip so as to minimize audible ticking.  It IS a nice convenient layout, but you may find the ticking soon overrides the convenience.

On the other hand, if folks have figured out a way to circumvent the ticking, using that layout, go to it.

RG Keen's layout works fine, but the extra components to de-tick will need to be added as "flying" components on the copper side.  Not a huge issue, though.

[Jason M.]

Here's my advice:

Save yourself the headache and stay away from the Zombie Chorus.
It has more ticks than a stray dog!

I built mine years ago using RG's layout and never got rid of the ticks and strange oscillations...even AFTER performing the mods Mr. Hammer refers to.

I did the bias mod and even added 0.1 ceramic caps right on the +V and ground pins to the ICs to decouple the power supply.
No luck.

Wish I had another project to suggest, but I never tried to build another chorus. EH small clones are cheap!

Do a search and see how many people had the same problems.

Good luck etching your first pcb. You'll get the hang of it in no time.

[MohiZ]

If you choose to take the previous poster's advice, I'd recommend the Small Clone as well. You can find the schematic on Tonepad, it sounds great and I've had no problems with ticking even without any mods.

[Mark Hammer]

IN many previous threads, people have come to the conclusion that, once you factor in all the changes that need to be made to have flawless performance, you may as well build the Small Clone clone, or the CE-2 clone.  I'm assuming that, since you were interested in building the Zombie, you have an MN3007 but not a 3101.  If this is the case, then try the Tonepad Small Clone layout, since you can probably get a CD4047 chip in your area.

[biggy boy]

Just went and looked at the tonpad Small clone PDF and saw the board layout.
If that was given to me to do as my first attempt at doing a board, I think I would have packed my bags and left town on the first train.
That circuit looks scary LOL.  I like to follow the k.i.s.s. approach, cuz well I'm the last "S" in that acronym!

[1878]

Ooh. Is it that bad ?? I'll probably still build it though, if only for the learning curve. I've got all the parts in my box, so it'd almost be rude not to  I was given 5 x MN3007's (along with some other goodies) by someone I work with. I have no idea where he got them from ?!?!

Just looked at the Small Clone layout and it seems a bit too much for a first go at etching. Thanks for the input though. I wont set my hopes too high for the final build.

[MohiZ]

Aww, don't be scared. I did the Small Clone as my 4th build, I think. It's just big, that's all there is to it. But yeah, maybe something a little easier for the first pedal