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Hi All,
I am not trying to start an argument, but I would like to point out
that PID controllers are only
good at controlling a certain class of system.
For a system that has a coal truck that must dump its coal down a
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Maybe because it was written back in 1930's, but one of the better
discussions of quartz temperature control, including considerations
of insulation and isothermal layers (attenuation and conduction)
are in the patents for the
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Neville Michie wrote:
Hi All,
I am not trying to start an argument, but I would like to point out
that PID controllers are only
good at controlling a certain class of system.
For a system that has a coal truck that must
Neville Michie wrote:
I am not trying to start an argument, but I would like to point out
that PID controllers are only
good at controlling a certain class of system.
The thermal block controllers work well because of the dominant
integrating effect of the block,
the time delay for a
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The 10811 has an ANALOG oven control loop. The gain is set
to be just below the oscillation point. This is due to the
stability limits dictated by the oven mass and (believe it
or not) the size of integrator capacitor that
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Dear Time-Nuts members,
A member of your list, Pete Rawson, suggested I let your members know about
our company, and its products, that has a relatively new US presence.
We design, manufacturer, and market a complete
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At HP, in the 90's, we did a lot of brainstorming about vacuum ovens.
This never seemed to make sense to us. If you actually
achieve high amounts of thermal resistance, then you can't
get the heat out of the oven. And if you
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Hi Tom:
Very interesting. How about building a circuit to drive those GR crystals?
The same man is the inventor of all four of the early GR patents, James Kilton
Clapp, of Clapp Oscillator fame.
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On 11/10/2007, at 10:23 PM, Bruce Griffiths wrote:
If one uses resistive heating then some linearisation improves the
performance as the heat from the heating element is proportional to
the
square of the voltage across
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Neville Michie wrote:
If you use a transistor as a heater, the full supply voltage is
across the
element all the time, so heating is proportional to the current flowing.
Neville
Neville
However using a transistor
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[EMAIL PROTECTED] wrote:
Hi Rick,
thanks for the pointers to the E1938A oven quality.
Today there are some interesting new technologies which allow small double,
or even tripple (not sure if that makes sense) ovens
We went through this tradeoff on the E1938A. Resistive heaters
can be distributed. However, it is very inefficient to drive
them with transistors, because then you waste a lot of power
heating the transistors, which is waste heat if resistive heating
is used. Prior to the 10544, they just put
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Rick Karlquist N6RK wrote:
If you want to soup up at 10811 oven, externally wire in a
larger capacitor in parallel and change the resistors to increase
the gain. The 10811 designers did the best they could with
what they
From: Bruce Griffiths [EMAIL PROTECTED]
Subject: Re: [time-nuts] Improving the stability of crystal oscillators
Date: Fri, 12 Oct 2007 10:08:34 +1300
Message-ID: [EMAIL PROTECTED]
Hej Bruce and Neville,
Neville Michie wrote:
If you use a transistor as a heater, the full supply voltage is
In a message dated 10/11/2007 14:31:04 Pacific Daylight Time,
[EMAIL PROTECTED] writes:
The lack of radiation shields and an isothermal block enclosing the
oscillator components within the vacuum will surely reduce the
performance somewhat.
Bruce
Hi Bruce,
yes I would agree, the spec
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In a message dated 10/11/2007 11:52:37 Pacific Daylight Time,
[EMAIL PROTECTED] writes:
Maybe Vectron has figured out something we didn't think of or
has sufficiently difference constraints that a vacuum makes
sense for
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Jeffrey Pawlan said the following on 10/07/2007 12:03 PM:
All larger TV stations use Cs standards. What you don't know is that the FCC
assigns SLIGHTLY different scan frequencies to each station on the same
channel in a
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