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Date: Fri, 6 Mar 2015 10:56:31 -0500
Message-ID: <CAM2RGhT9jkb4OOKddvUcKGyhnu0P4KaKTmh1kT84YFVMpM-_Cg@mail.gmail.com>
Subject: Re: [geda-user] [OT] Temperature sensor and control recommendation
From: Evan Foss <evanfoss AT gmail DOT com>
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Ok.

On Fri, Mar 6, 2015 at 10:49 AM, John Griessen <john AT ecosensory DOT com> wrote:
> On 03/06/2015 08:55 AM, Evan Foss wrote:
>>
>> Why is everyone assuming this should be done digitally?
>
>
> 0.3 deg C is close to the tolerances of thermocouples you can buy,
> and the temperature dependencies of the control circuit are
> in that range also.  With so much needing calibration to get rid of offsets
> and drifts, programmable seems the way to get whole-system accuracy.
> Precision
> is easy to get with digitizers and sigma delta tech, which leaves
> accuracy of the whole system, and it's difficult and time consuming
> to iterate the design of an analog machine exposed to fluctuating ambient
> outside the oven, and sensor drift as it gets broken in with use over weeks.



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