[time-nuts] Making a HP 10811 and similar types better in the

Rick Karlquist richard at karlquist.com
Thu Sep 22 01:38:15 UTC 2011


ws at Yahoo wrote:
>
>    As already stated, there are many different ways to design and or tune
> a
> temperature controller so it does not overshoot.

The 10811 control loop is constrained by the large oven mass
and the limited size of the integrator capacitor.  The
capacitor is barely large enough in capacitance to prevent
loop oscillation but on the other hand is barely small
enough to physically fit in the available space.  Unfortunately, no
advances in capacitor size have occurred in the last 30
years, so we are still stuck with the original design.
BTW, you cannot use a metallized mylar capacitor in an
integrator, you must use a foil and mylar type.  This is
due to the "healing" process that metallized mylar
capacitors undergo.

Rick Karlquist




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