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

[mark verbos]

Everything is powered from the Q ground with the exception of the LED  
stuff. In other words, the 2 places you see N on the schematic are  
the only places that N goes to. In reality, you would likely be fine  
just wiring all the grounds together.

Mark




On Dec 20, 2008, at 2:11 AM, Aaron Lanterman wrote:

> 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
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