[sdiy] Quiet/noisy grounds on Music Easel envelope generator

[Aaron Lanterman]

Howdy folks,

I'm working on getting the envelope generator for the Music Easel into  
Eagle for PCB goodness (yup, I plan to make this and other related  
PCBs available if and when I get them done and debugged):

http://rubidium.dyndns.org/~magnus/synths/companies/buchla/Buchla_2080_3_200.jpg

There's three digital chips in that circuit: A MC14001, an MC14025,  
and a MC14016 quad bilateral switch. There's a bunch of analog stuff,  
including some op amps and a LM3900 norton amp.

Like most Buchla designs, this schematic employs a "noisy ground" and  
a "quiet ground."

I'm guessing that I should power the three digital chips with +15 V  
and "noisy ground," and I should power the LM3900 with +15 V and  
"quiet ground." But, there's no specific mention of any of this on the  
data sheet.

Anyone see anything wrong with my plan?

(The MC14016 is a "digital" chip, but it is passing analog signals,  
which lead me to wondering...)

- Aaron