[sdiy] Zener issues (again)

[David G Dixon]

Well, it was the zeners.  I swapped the old ones in and the circuit worked
perfectly.  What a shit-show.

I think maybe I'll order some 1N5231s instead.  They are rated for half the
power dissipation, so they should all work, right?  Right?  Plus, Newark has
Vishay ones on sale for $0.03 apiece.

 

-----Original Message-----
From: Roman Sowa [mailto:modular at go2.pl] 
Sent: Sunday, November 29, 2020 11:56 PM
To: David G Dixon; 'synth-diy mailing list'
Subject: Re: [sdiy] Zener issues (again)

[CAUTION: Non-UBC Email]

It's not the first time that you write here about counterfreight parts. 
Maybe you should consider changing regular parts source?
1W and 5W zener definitely need different package, so the mistake was made
on the die level. If it wasn't checked before packaging, it could have been
some small garage IC maker deep in China forest. Or rice field, China does
not have much forest I think.

Make one measurement - voltage at the test current shown in datasheet that
is 49mA for one and 240mA for the other diode. You'll know for sure.
BTW, when I searched for datasheets for them, it showed up about 20
different brands making those diodes, and I have never heard of any of them.
That sort of tells you what kind of reliability and repeatability to expect.

BTW2, instead of 5.1V zener you can use 5V R-R opamp for clipping trapezoids
and it will work much more precise, plus free buffering.