[time-nuts] Ovens

Rick Karlquist richard at karlquist.com
Tue Aug 17 13:36:20 EDT 2004


Brooke Clarke said:
> Hi:
>
> HP did quite a bit of research on isothermal oven design.  The idea is
> that you can draw a line in three dimensional space where the
> temperature is constant.  Since you can not have the temperature sensor
> and the device being controlled in the same place it's important to have
> them both on an isothermal line.  Then the trick is to get the system
> gain as high as possible.
>

In the 10811, this is accomplished by ratioing the power to
2 heater transistors.  You can tweak the ratio in an individual
10811 to optimize its thermal gain.  A thermal gain of about 1000
can be achieved.  The E1938A goes beyond this theory, and keeps
the temperature constant over a volume, not a line.
(See http://www.karlquist.com/oven.pdf).  A thermal gain of
over 1,000,000 can be achieved in a single (not double) oven this
way.

Rick Karlquist




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