[sdiy] Through zero quadrature oscillator

ulfur hansson ulfurh at gmail.com
Tue Oct 9 14:33:01 CEST 2018

this is actually super helpful and interesting - the circuit used in his
frequency shifter seems to be an improved version, and i'll definitely
breadboard it this week. thank you so much Guy!

i'm starting to think that the first prototype I built might be unstable.
the LM13700's are oscillating/heating up in this configuration, but the PSU
is very good (same cincon converters used in the deckards dream) and all
power rails are properly filtered -

are there any standard methods to help further stabilize a circuit like
this, to prevent it from going into high frequency oscillation?


þri., 9. okt. 2018 kl. 01:32 skrifaði Guy McCusker <guy.mccusker at gmail.com>:

> This isn't necessarily going to help with the question but I thought
> the list might enjoy poking around the web site of the designer of
> that oscillator circuit, which doesn't seem to be too well known. I
> found it recently after reading a post somewhere by Ian Fritz which
> referred to "Henry's frequency shifter" -- a little googling turned up
> this site. (Thanks Ian for the pointer!)
> Section 2.2 of this page
> http://www.interestingelectronics.com/old/henrys_interesting_electronics/frequency_shifter/frequency_shifter.htm
> describes the TZQVCO and includes a slightly more readable schematic.
> And there are some other interesting things on the other pages.
> On Tue, Oct 9, 2018 at 12:54 AM ulfur hansson <ulfurh at gmail.com> wrote:
> >
> > hello list,
> >
> > I intend to design a small synthesizer with two through zero independent
> sine oscillators capable of FM modulating each other.
> >
> > so far, this is the most intriguing sine core design I have found. the
> article that accompanies it is also pretty good ::
> https://we.tl/t-8OE3khwl07
> >
> > after laying out the design and building it a couple of times, the
> circuit fails to oscillate - however -i really like the idea of using a
> sine-core oscillator rather than waveshaping a triangle, and would rather
> continue to pursue that avenue further. the fact that this design is
> quadrature also is just an added bonus for me :)
> >
> > I know it is impossible for anyone to help me troubleshoot a circuit
> remotely - but any pointers towards more literature on through zero sine
> oscillator core designs, or thoughts on the above circuit design would be
> immensely well appreciated!
> >
> > thanks for reading,
> > -úlfur
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