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<DIV dir=ltr align=left><SPAN class=921325618-30112020><FONT color=#0000ff
size=2 face=Arial>Hi Rutger,</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=921325618-30112020><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=921325618-30112020><FONT color=#0000ff
size=2 face=Arial>Well, when I simulated my circuit with 5W zeners (1N5338) it
behaved more or less like the actual circuit, so I believe it is the power
dissipation rating. For my application, the capacitance would really have
to be through the roof to affect things that much.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=921325618-30112020><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=921325618-30112020><FONT color=#0000ff
size=2 face=Arial>I need to quit screwing around and just order lower power
zeners for all my designs.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=921325618-30112020><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=921325618-30112020><FONT color=#0000ff
size=2 face=Arial>Cheers, Dave</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> Rutger Vlek [mailto:rutgervlek@gmail.com]
<BR><B>Sent:</B> Monday, November 30, 2020 10:25 AM<BR><B>To:</B> David G
Dixon<BR><B>Cc:</B> Roman Sowa; synth-diy mailing list<BR><B>Subject:</B> Re:
[sdiy] Zener issues (again)<BR></FONT><BR></DIV>
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Non-UBC Email]</SPAN></SPAN></SPAN>
<DIV dir=auto>Could it have been a difference in the capacitance of the zeners?
I recall discussing zener capacitance with Ian Fritz as we both ran into it when
designing the saturation stage of a filter and had problems with HF tracking of
self-oscillation.
<DIV dir=auto><BR></DIV>
<DIV dir=auto>Rutger</DIV></DIV><BR>
<DIV class=gmail_quote>
<DIV dir=ltr class=gmail_attr>Op ma 30 nov. 2020 09:39 schreef David G Dixon
<<A href="mailto:dixon@mail.ubc.ca">dixon@mail.ubc.ca</A>>:<BR></DIV>
<BLOCKQUOTE
style="BORDER-LEFT: #ccc 1px solid; MARGIN: 0px 0px 0px 0.8ex; PADDING-LEFT: 1ex"
class=gmail_quote>Well, it was the zeners. I swapped the old ones in and
the circuit worked<BR>perfectly. What a shit-show.<BR><BR>I think maybe
I'll order some 1N5231s instead. They are rated for half the<BR>power
dissipation, so they should all work, right? Right? Plus, Newark
has<BR>Vishay ones on sale for $0.03 apiece.<BR><BR><BR><BR>-----Original
Message-----<BR>From: Roman Sowa [mailto:<A href="mailto:modular@go2.pl"
rel=noreferrer target=_blank>modular@go2.pl</A>] <BR>Sent: Sunday, November
29, 2020 11:56 PM<BR>To: David G Dixon; 'synth-diy mailing list'<BR>Subject:
Re: [sdiy] Zener issues (again)<BR><BR>[CAUTION: Non-UBC Email]<BR><BR>It's
not the first time that you write here about counterfreight parts. <BR>Maybe
you should consider changing regular parts source?<BR>1W and 5W zener
definitely need different package, so the mistake was made<BR>on the die
level. If it wasn't checked before packaging, it could have been<BR>some small
garage IC maker deep in China forest. Or rice field, China does<BR>not have
much forest I think.<BR><BR>Make one measurement - voltage at the test current
shown in datasheet that<BR>is 49mA for one and 240mA for the other diode.
You'll know for sure.<BR>BTW, when I searched for datasheets for them, it
showed up about 20<BR>different brands making those diodes, and I have never
heard of any of them.<BR>That sort of tells you what kind of reliability and
repeatability to expect.<BR><BR>BTW2, instead of 5.1V zener you can use 5V R-R
opamp for clipping trapezoids<BR>and it will work much more precise, plus free
buffering.<BR><BR>_______________________________________________<BR>Synth-diy
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