Author Topic: Parts layout for MN3207 Zombie wanted  (Read 1196 times)

Mark Hammer

Parts layout for MN3207 Zombie wanted
« on: December 07, 2020, 08:06:34 PM »
I have a layout for an MN3207-based Zombie Chorus that someone posted, and I have a schematic.  What I'm missing is where to put the components that the layout provides for.  Can someone point me to one?  Thanks in advance.


bean

Re: Parts layout for MN3207 Zombie wanted
« Reply #1 on: December 07, 2020, 08:32:40 PM »

Mark Hammer

Re: Parts layout for MN3207 Zombie wanted
« Reply #2 on: December 08, 2020, 09:11:07 AM »
I don't know who drew it, but I'd had trouble with another chorus layout from there that was drawn for an MN3007.  Turned out the modding it to work with a 3207 was going to be more complicated and uncertain.  This layout purports to be for a 3207, and it may well be just that.  The detective work to figure out where things ought to go just isn't worth my time, though.  If I have a parts overlay, I may etch and stuff it, but not unless I know I can end up with a working circuit.  Otherwise, it would just be easier to perf one using the schematic.

Marcos - Munky

Re: Parts layout for MN3207 Zombie wanted
« Reply #3 on: December 08, 2020, 10:31:33 AM »
I checked the link posted by Bean and took a look at the comments. One person posted a MN3207 version, but the link was broke. They said it was also posted here, so I did a search and found this one:
https://www.diystompboxes.com/smfforum/index.php?topic=123867.msg1175983#msg1175983

Mark Hammer

Re: Parts layout for MN3207 Zombie wanted
« Reply #4 on: December 08, 2020, 10:49:35 AM »
Hah!  That's the one.  Thanks a million Marcos.  VERY much appreciated.  :icon_biggrin:

Marcos - Munky

Re: Parts layout for MN3207 Zombie wanted
« Reply #5 on: December 08, 2020, 02:09:41 PM »
Glad to help. Hope it sounds good, the Zombie is a very nice chorus and what makes it hard to build is the MN3007. If it sounds good with the easier to get MN3207, it'll be good news for people looking for a bbd chorus.

RickL

Re: Parts layout for MN3207 Zombie wanted
« Reply #6 on: December 08, 2020, 09:37:42 PM »
What am I missing? The layout using the 3007 sends +9V to pin 1 of the 3007 (ground) and ground to pins 4 and 5 (Vgg and Vdd). This gives the required (relative) negative Vdd/Vgg to the 3007.

If you reverse +9v and ground for the 3207 circuit you get the required positive Vdd/Vgg but it also reverses the voltages on the 4558 and 4016. How do the 4558 and 4016 work with a negative power supply?

bean

Re: Parts layout for MN3207 Zombie wanted
« Reply #7 on: December 08, 2020, 11:56:12 PM »
What am I missing? The layout using the 3007 sends +9V to pin 1 of the 3007 (ground) and ground to pins 4 and 5 (Vgg and Vdd). This gives the required (relative) negative Vdd/Vgg to the 3007.

If you reverse +9v and ground for the 3207 circuit you get the required positive Vdd/Vgg but it also reverses the voltages on the 4558 and 4016. How do the 4558 and 4016 work with a negative power supply?

- The voltage pin reverse is only for the MN3207 (which is N-channel instead of P-channel internally). You don't need to reverse voltage on anything else. You just have to remember that MN3207 is opposite in its polarity from MN3007 in a negative ground circuit.
- Couple other points - output mixing in MN3007 is usually done in conjunction with a pullup resistor whereas with MN3207 it should be pulldown (IOW supply vs. gnd).
- VGG with MN3207 is calculated as 14/15 the supply voltage.
- With MN3007, VGG is the inverse: Vgg= 1-V(14/15), where V is your supply voltage. Correction, I meant to say V-V(14/15) which is V(0.067). Hopefully I got that right this time.
- Same goes for MN3005/MN3205

Caveat - this is what I remember off the top of my head but I still get confused with these even after using them both for more than a decade. If I'm wrong I'm sure someone else can correct.
« Last Edit: December 09, 2020, 10:17:16 AM by bean »

RickL

Re: Parts layout for MN3207 Zombie wanted
« Reply #8 on: December 09, 2020, 12:46:13 AM »
That's what I don't understand. If I'm reading the link correctly, it says that the layout will work for  a 3207 by simply reversing the voltages (plus the minor corrections needed for both versions - 10k to 10n and added 100k) on the board. That won't just reverse the voltages on the delay chip, it will reverse them on the 4558 and the 4016.

Did I miss a link on that page that changes the layout so the voltages are only reversed on the delay chip?

Mark Hammer

Re: Parts layout for MN3207 Zombie wanted
« Reply #9 on: December 09, 2020, 09:11:20 AM »
Hi Rick.

And just to clarify, that should read 4046, not 4016.  ;)

deadastronaut

Re: Parts layout for MN3207 Zombie wanted
« Reply #10 on: December 09, 2020, 11:59:26 AM »
just my 2p...

i had distortion when using humbuckers with the zombie and just couldnt get rid of it no matter what i did, (tested at nauseam on breadboard)...if you whack a chord it would never be clean.....gave up and went a different route.

its ok if you use single coils though...(which i dont)  :icon_mrgreen:

as you were....
https://www.youtube.com/user/100roberthenry
https://deadastronaut.wixsite.com/effects

chasm reverb/tremshifter/faze filter/abductor II delay/timestream reverb/dreamtime delay/skinwalker hi gain dist/black triangle OD/ nano drums/space patrol fuzz//

Lordrahulcool

Re: Parts layout for MN3207 Zombie wanted
« Reply #11 on: September 19, 2021, 11:09:03 PM »
@mark hammer

Did it work?

Is that pic already reversed?