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

[ws at Yahoo]

I hope it is not being suggesting that is an optimal PI  (no D) oven 
controller for limiting overshoot.
Many other ways to do it with less overshoot IF that was needed or wanted.

>From the test I've done on it, Less overshoot is not necessary and likely 
not desired.
It overshoots a little but does not ring which is near the optimal tuning 
for a simple basic PI controller.
And of course today there is always the choice to rise the resistor values 
and use a  better amp which has the same effect as rising the cap's value.


ws

****************************

>Rick Karlquist richard at karlquist.com wrote:

>> 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