<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META content="text/html; charset=us-ascii" http-equiv=Content-Type>
<META name=GENERATOR content="MSHTML 8.00.6001.23562"></HEAD>
<BODY style="WORD-WRAP: break-word; -webkit-nbsp-mode: space">
<DIV dir=ltr align=left><SPAN class=162274920-08012021><FONT color=#0000ff
size=2 face=Arial>I have the same experience. Poly film caps oscillate
much easier than C0G caps of the same value. I have replaced C0G with WIMA
polyester to get stable oscillation in filters.</FONT></SPAN></DIV><BR>
<DIV dir=ltr lang=en-us class=OutlookMessageHeader align=left>
<HR tabIndex=-1>
<FONT size=2 face=Tahoma><B>From:</B> Synth-diy
[mailto:synth-diy-bounces@synth-diy.org] <B>On Behalf Of </B>Tom
Wiltshire<BR><B>Sent:</B> Friday, January 08, 2021 7:26 AM<BR><B>To:</B>
ColinMuirDorward<BR><B>Cc:</B> synth-diy@synth-diy.org<BR><B>Subject:</B> Re:
[sdiy] VCF caps in modern synths<BR></FONT><BR></DIV>
<DIV></DIV><SPAN
style="BACKGROUND-COLOR: #ffecb3; COLOR: #000000; FONT-SIZE: 12px"><SPAN
style="BACKGROUND-COLOR: #ffecb3; COLOR: #000000; FONT-SIZE: 12px"><SPAN
style="PADDING-BOTTOM: 3px; LINE-HEIGHT: 1.6; BACKGROUND-COLOR: #ffecb3; FONT-STYLE: normal; PADDING-LEFT: 3px; PADDING-RIGHT: 3px; COLOR: #000000; FONT-SIZE: 12px; FONT-WEIGHT: normal; PADDING-TOP: 3px">[<STRONG>CAUTION:</STRONG>
Non-UBC Email]</SPAN></SPAN></SPAN><BR>
<DIV><BR>
<BLOCKQUOTE type="cite">
<DIV>On 8 Jan 2021, at 16:02, ColinMuirDorward <<A
href="mailto:colindorward@gmail.com">colindorward@gmail.com</A>>
wrote:</DIV><BR class=Apple-interchange-newline>
<DIV><SPAN
style="TEXT-TRANSFORM: none; FONT-STYLE: normal; TEXT-INDENT: 0px; DISPLAY: inline !important; FONT-FAMILY: Helvetica; WHITE-SPACE: normal; FLOAT: none; LETTER-SPACING: normal; FONT-SIZE: 12px; FONT-WEIGHT: normal; WORD-SPACING: 0px; TEXT-DECORATION: none; caret-color: rgb(0, 0, 0); font-variant-caps: normal; -webkit-text-stroke-width: 0px">Yesterday
I did some very non-scientific testing of 3320 4pole BPF built using C0G vs
polypropylenes. The test may have been more about the tolerances of the caps
rather than the dielectric, since my polys are 2.5% vs the C0Gs at 5%. I
noticed that at lower frequencies, the polypropylene version would go into
oscillation before the C0G version. Any thoughts on
this?</SPAN></DIV></BLOCKQUOTE></DIV><BR>
<DIV>Yes, I think you’re right. That seems more likely to be an effect of the
tolerance to me.</DIV>
<DIV><BR></DIV>
<DIV>Tom</DIV>
<DIV><BR></DIV>
<DIV>
<DIV>==================<BR> Electric Druid<BR>Synth
& Stompbox DIY<BR>==================</DIV>
<DIV><BR></DIV></DIV></BODY></HTML>