Re: Sinewave oscillator without gain control.

On 24/01/2025 11:40, albert@spenarnc.xs4all.nl wrote:

In article <vmum11$n7g$1@nnrp.usenet.blueworldhosting.com>,
Edward Rawde <invalid@invalid.invalid> wrote:
<SNIP>

This will show that this circuit is approaching 120dB down on harmonics.
So if you want to do better than that then you'll need an oscillator
circuit which has better performance to begin with. You can
then add gain control for constant level.
I've not so far found an oscillator circuit in LTSpice with better
harmonic distortion performance than this one.
You can, of course, try to use filtering to reduce the unwanted
harmonics. Removing the first four harmonics produced by this
circuit will get it approaching 130dB but don't ask me how that would be
measured in reality or what it would cost to do so even if
it can be measured.

 If I read the specs on capacitors, I fear that even a passive filter
would increase the distortion unless rigid air capacitors are used.
Comment?
In general:
In how far are passive electronic components ideal, distortion free?
(I read bad things about SMD capacitors.)
 Groetjes Albert

COG/NPO ceramics do not have the extreme non-linearities of some of the
other types.  Nor are they piezoelectric.
The only problem is that anything larger than about 10nF gets large,
expensive and possibly unobtainable.
PPS capacitors are available in larger values and have a low, but
not zero voltage coefficient.
John