<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META http-equiv=Content-Type content="text/html; charset=iso-8859-1">
<META content="MSHTML 6.00.2800.1400" name=GENERATOR>
<STYLE></STYLE>
</HEAD>
<BODY bgColor=#ffffff>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=902140216-17032005>Bill,</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=902140216-17032005></SPAN></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=902140216-17032005>2)</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=902140216-17032005></SPAN></FONT> </DIV>
<DIV><FONT><SPAN class=902140216-17032005><FONT face=Arial color=#0000ff
size=2>Another issue is that the attack, decay and release pots on envelope
generators are typically log pots, a non-linear scale. So if the digital
pots you use are not log they may not give you the timing resolution that you
are use to. One techinque to do that is buffer the pot and add a resistor.
Picking the right resistor and placing it between the wiper and the other ends
of the pot (assuming using pot as attenuator between signal and gnd) can give
you log or expo curves. Try </FONT><A
href="http://www.geofex.com/Article_Folders/potsecrets/potscret.htm"><FONT
face=Arial color=#0000ff
size=2>http://www.geofex.com/Article_Folders/potsecrets/potscret.htm</FONT></A><FONT
face=Arial color=#0000ff size=2> </FONT></SPAN></FONT><SPAN
class=902140216-17032005><FONT face=Arial color=#0000ff size=2>for that
info.</FONT></SPAN></DIV>
<DIV><SPAN class=902140216-17032005><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=902140216-17032005><FONT face=Arial color=#0000ff size=2>Good
luck.</FONT></SPAN></DIV>
<DIV><SPAN class=902140216-17032005><FONT face=Arial color=#0000ff size=2>Jay
S.</FONT></SPAN></DIV>
<BLOCKQUOTE dir=ltr
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #0000ff 2px solid; MARGIN-RIGHT: 0px">
<DIV class=OutlookMessageHeader dir=ltr align=left><FONT face=Tahoma
size=2>-----Original Message-----<BR><B>From:</B>
owner-synth-diy@dropmix.xs4all.nl
[mailto:owner-synth-diy@dropmix.xs4all.nl]<B>On Behalf Of </B>Bill
Berzinskas<BR><B>Sent:</B> Thursday, March 17, 2005 7:36 AM<BR><B>To:</B>
synth-diy@dropmix.xs4all.nl<BR><B>Subject:</B> [sdiy] 5v ADV Bass / AD EG
Question. <BR><BR></FONT></DIV>
<DIV><FONT face=Arial size=2>Hello everybody.. just woke up to a crazy
little burst of snow here in NC.. wierd.. </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Anyhow.. As you probably know i'm
modding the bejezzus out of my adv-bass.. In my quest to make it
digitally controlled, i've hit a few snags.. so maybe you can help me
out.. </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>1) I am converting it to digital
control.. mostly thru digital pots.. a few things with
DAC.. so.. for the digital pots, i have to use 5v input, and rather then
use way more opamps then i want to deal with, i would like to make it operate
on 5v possibly with a bipolar or just 12v output stage if
necessary.. So.. </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I've done some crude experiments with the Trigger
section just to see how it reacts to switching from +/-12v to just
+5v.. I've tried with tl082s.. and i just can't get
the trigger ratio right.. and it always triggers.. so.. since i broke down and
got a few lm324s, i tried those.. and it seems to be working
correctly.. i then went on and built the impact part using the
digital potentiometers.. all good so far.. if i just
switch all my opamps in the design, will it carry through the rest of the
circuit properly? </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>2) I plan to use a digital potentiometer to
control the decay time.. but the highest value i can come up with
is 100k.. so i'm thinking i can change the capacitor and get about the same
decay time? any recommendations for a value? </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>thanks guys! :-) </FONT></DIV>
<DIV><FONT face=Arial size=2>--billie</FONT></DIV>
<DIV> </DIV></BLOCKQUOTE></BODY></HTML>