[sdiy] Temperature Compensated VCO attempt - help?

[patchell]

Magnus Danielson wrote:

>
> In the neighborhood of 45 ppm/C is much much better than the uncompensated case
> of 3300 ppm/C. When you are looking at that kind of temperature sensitivites I
> think the milage can vary depending on what other components are in the VCO.
>

    It is also a lot better than the 400ppM/C I was getting with the previous temp
sensor... :-)

>
> Jörgen reporten on what seemed to be temperature dependence on the LM311
> comparator in one of his designs. Both resistors and caps can also change
> depending on which quality was chosen.
>
> Anyway, it seems mighty encouraging. The question I'd like to ask, at least
> retorically, is which stability is needed?

    I have always been more concerned with scale drift.  Offset drift can be fixed
by simply adjusting the frequency control knob, but when the scale changes, all you
can do is retune...by the way, the last number I took gave me a tempco of
-67ppM/C...when I have measured the scale factor in the past, I generally get a
+/-100ppM/C scatter.

    It is going to be hard to control myself from sending boards out to be
fabbed...

>
>
> Cheers,
> Magnus

--
 -Jim
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