[sdiy] filtering out a saw-reset glitch in a triangle shaper

[Ingo Debus]

Am 09.09.2009 um 02:45 schrieb David G. Dixon:

> I'm actually liking the active full-wave rectifier plus 5.1V zener  
> method
> more and more.  Slap a 15pF cap across the feedback loop of the  
> final level
> shifting and inverting opamp, and the final -5 to +5V triangle looks
> virtually perfect.

Haven't followed the thread too closely, so I don't know the details  
of this circuit; but did you take the tolerance of the zener voltage  
into account? Looking at the data sheet of a random 5.1 volts zener  
diode (1N5231B), the voltage can vary between 4.845 and 5.355 volts.  
So if you're unlucky, either a bit of the glitch will still be there,  
or your triangle gets quite mis-shaped. Or you need to trim the  
amplitude or offset of the triangle.

Ingo