Strange Zombie behaviour

[Mark Hammer]

So, I perfed up a build of Marco Cardenas MN3207-based version of the Zombie Chorus (thank you Marco! ).  Yes, there is probably a layout posted somewhere, but I needed it to fit inside a specific chassis, so perf it was.  Happily, the thing booted up fine the first time, once I got the two different adjustable voltages right.

But here's the thing.  The delay time was much longer than expected.  Indeed, the delay time was audible AS delay, like a very very short slapback, and the thing didn't start to sound very chorus-like at all unless I dropped the clock capacitance down around the 360pf range, and trimmed the sweep width back most of the way.  Popping out the MN3207 and replacing it with an MN3209 (only 256 stages, so 1/4 the delay time), however, nailed me the sort of chorus tones I was expecting.

So, naturally, I find this all rather perplexing.  Any of you folks have any ideas about why the clock rate would be so slow as to provide annoyingly (and I must say, poor quality) delays out of the BBD?  Is there a pin on the 4046 I should check?  Is there a pin I probably should have connected in some manner but neglected to during the flipping around that is a natural part of perfing?

Note that the original circuit is predicated on an MN3007, and Marco has adapted it to the MN3207.  The 3207 normally assumes a lower supply and bias voltage than the 3007 but the circuit runs/biases it off a basic 9v (which it CAN use).

[biggy boy]

Hi Mark
Have you made any headway on this?
I got all the parts to make the original Zombie with the 3007 and 4046, but have stopped dead in my tracks after reading about the ticking problems!?!?!
Just wondering if you got things going OK on yours with the different parts?


Glen

[deaconque]

I read the title of this thread and clicked on it with entirely different expectations (i wasn't thinking of the zombie chorus)