AN-72

[gstopp at fibermux.com]

     I am also curious about the 3900 - I have never built anything that 
     uses one. My only experience was buying a broken Odyssey long ago ($40 
     I think) and fixing it by replacing the 3900 in the un-epoxied VCF 
     module. I don't even understand how they work. I do know that there 
     are some circuits in Electronotes, and even some theory discussion, 
     but I never bothered to pay close attention to them. Also I know that 
     I've seen it used in Serge schematics too.
     
     I have several in my desk here.... uh oh, I feel some proto-board 
     circuits are in my future....
     
     - Gene


______________________________ Reply Separator _________________________________
Subject: AN-72
Author:  Haible Juergen <Juergen.Haible at nbgm.siemens.de> at ccrelayout
Date:    2/25/97 4:48 AM


Looked around Nationals AppNote page 
http://www.national.com/apnotes/ap_notes_all.html,
and found AN-72 about the LM3900. They had a much simpler 
charge-pump / staircase generator than mine (as on synthfool). 
Hey, they just need a single diode to have both edges inject 
charge into the integrator!
Now .. didn't Serge use the 3900 a lot ??
I also found a circuit with a pnp pair in front of a 3900 - looks 
very similar to this 3900-based ARP 4pole filter!
Just thought I'd share this with you - personally, I have not 
much experience with Norton amps.
     
JH.