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From: Cursitor Doom <cd999666@notformail.com>
Newsgroups: sci.electronics.design
Subject: Re: A collection of monographs on high accuracy electronics
Date: Wed, 19 Jun 2024 17:41:16 -0000 (UTC)
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On Tue, 18 Jun 2024 23:32:40 -0000 (UTC), Phil Hobbs wrote:

> JM <sunaecoNoSpam@gmail.com> wrote:
>> On Mon, 17 Jun 2024 07:09:12 -0700, john larkin <jl@650pot.com> wrote:
>> 
>>> On Sun, 16 Jun 2024 22:20:43 +0100, JM <sunaecoNoSpam@gmail.com>
>>> wrote:
>>> 
>>>> On Tue, 11 Jun 2024 19:11:51 -0700, john larkin <jl@650pot.com>
>>>> wrote:
>>>> 
>>>>> On Wed, 12 Jun 2024 02:50:19 +0100, JM <sunaecoNoSpam@gmail.com>
>>>>> wrote:
>>>>> 
>>>>>> On Mon, 10 Jun 2024 15:14:40 -0400, Phil Hobbs
>>>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote:
>>>>>> 
>>>>>>> On 2024-06-09 21:43, Phil Hobbs wrote:
>>>>>>>> On 2024-06-09 20:55, JM wrote:
>>>>>>>>> On Mon, 10 Jun 2024 00:29:17 -0000 (UTC), Phil Hobbs
>>>>>>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote:
>>>>>>>>> 
>>>>>>>>>> JM <sunaecoNoSpam@gmail.com> wrote:
>>>>>>>>>>> On Sun, 9 Jun 2024 18:09:24 -0000 (UTC), Phil Hobbs
>>>>>>>>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote:
>>>>>>>>>>> 
>>>>>>>>>>>> Jeroen Belleman <jeroen@nospam.please> wrote:
>>>>>>>>>>>>> On 6/9/24 19:02, ehsjr wrote:
>>>>>>>>>>>>>> On 6/7/2024 9:14 PM, JM wrote:
>>>>>>>>>>>>>>> A collection of monographs on high accuracy electronics
>>>>>>>>>>>>>>> written by Mr.
>>>>>>>>>>>>>>> Chris Daykin, following his career predominantly in
>>>>>>>>>>>>>>> metrology.
>>>>>>>>>>>>>>> 
>>>>>>>>>>>>>>> Unfortunately Chris will be unable to complete the
>>>>>>>>>>>>>>> unfinished monographs (having started end of life care)
>>>>>>>>>>>>>>> but there is plenty of interest to any analogue engineer.
>>>>>>>>>>>>>>> 
>>>>>>>>>>>>>>> https://1drv.ms/b/c/1af24d72a509cd48/EZhO_rP5-
glDmxtc4ZHycvYBhrsqmyC5tuZjt2NFFsS0gQ?e=Wq2Yj0
>>>>>>>>>>>>>>> 
>>>>>>>>>>>>>>> 
>>>>>>>>>>>>>>> 
>>>>>>>>>>>>>> 
>>>>>>>>>>>>>> Thanks!
>>>>>>>>>>>>>> Ed
>>>>>>>>>>>>> 
>>>>>>>>>>>>> I have an issue with his definition of resistor noise power
>>>>>>>>>>>>> as the product of open-circuit noise voltage and
>>>>>>>>>>>>> short-circuit current. That makes no sense.
>>>>>>>>>>>>> 
>>>>>>>>>>>>> There's more than that, probably, but that just jumped out
>>>>>>>>>>>>> at me.
>>>>>>>>>>>>> 
>>>>>>>>>>>>> Jeroen Belleman
>>>>>>>>>>>>> 
>>>>>>>>>>>>> 
>>>>>>>>>>>> It?s four times too high, for a start.
>>>>>>>>>>>> 
>>>>>>>>>>>> Cheers
>>>>>>>>>>>> 
>>>>>>>>>>>> Phil Hobbs
>>>>>>>>>>> 
>>>>>>>>>>> "It is shown elsewhere [1] that the noise power is four times
>>>>>>>>>>> the heat energy which would flow down the conductors from a
>>>>>>>>>>> warm source resistor to a matching cold resistor."
>>>>>>>>>>> 
>>>>>>>>>>> 
>>>>>>>>>> Which, if true, would solve all our energy problems, except
>>>>>>>>>> that thermodynamic systems would all be unstable.
>>>>>>>>>> 
>>>>>>>>>> The thermal noise power produced by a resistor into a matched
>>>>>>>>>> load is kT per hertz.
>>>>>>>> 
>>>>>>>> 
>>>>>>>>> Sure, which is what he states.ÿ By mentioning a hot and cold
>>>>>>>>> resistor he makes it clear that net energy flow is from hot to
>>>>>>>>> cold, and that the T refers to the hot source.
>>>>>>>>> 
>>>>>>>> But apparently he says that it's four times larger than that.
>>>>>>>> 
>>>>>>>> I'm not making a microsoft account just to download the PDF, so
>>>>>>>> if you want to discuss it further, you could email it to me.
>>>>>>>> 
>>>>>>>> Cheers
>>>>>>>> 
>>>>>>>> Phil Hobbs
>>>>>>>> 
>>>>>>>> 
>>>>>>>> 
>>>>>>> Bill was kind enough to send me a copy (thanks again, Bill), and
>>>>>>> right there on P. 374, the author says,
>>>>>>> 
>>>>>>> Pn = 4kTB
>>>>>>> 
>>>>>>> which is a factor of four too high.
>>>>>>> 
>>>>>>> 
>>>>>> 
>>> 
>>>>>> No it isn't. He is calculating the thermal noise power dissipated
>>>>>> in an unloaded resistor - something (or at least the related noise
>>>>>> voltage) which is actually required in the design process of a
>>>>>> transducer/amplifier low S/N system.
>>> ===============================================
>>> 
>>> 
>>> 
>>>>> What does that mean? Do unconnected resistors get hot?
>>>>> 
>>>>> A box of resistors could start a fire!
>>>> 
>>>> And why would that occur.  In thermal equilibrium there is no net
>>>> transfer of energy either from or to the resistor (when averaged over
>>>> any time interval of interest appropriate to the bandwidth of current
>>>> electronic circuits).
>>>> 
>>>> The so called resistor thermal "available noise power" KTB implies
>>>> there is a net power delivery from a source to a load.  In the case
>>>> of maximum transfer the source must dissipate within itself exactly
>>>> the same as it delivers to the load (due to having the same
>>>> resistance). However if the so called load is at the same temperature
>>>> as the source it also delivers KTB to the source and dissipates KTB
>>>> within its own resistance.  Thus there is no net transfer of energy
>>>> between the two resistors in thermal equilibrium.  If one is at a
>>>> lower temperature than the other there will be a net transfer of
>>>> energy, but this will be completely dwarfed in any practical system
>>>> by the energy transferred due to thermal conductivity between the two
>>>> resistors.
>>>> 
>>>> So the power dissipated in a system of two equal value resistors is
>>>> 4KTB.  But this also holds if the two resistors have different
>>>> values, including the situation where one of the resistors is a short
>>>> or open circuit (i.e. leaving a single open or short circuit
>>>> resistor).  So it is entirely reasonable to state (as many engineers
>>>> do) that the thermal noise power of a resistor is 4kTB.
>>> 
>>> If as stated "the thermal noise power dissipated in an unloaded
>>> resistor" is nonzero, a reel of 0805s is a fire hazard. What would
>> 
>> No taxation without representation No chilli without beans No
>> fluctuation without dissipation
>> 
>> Which one is true?
> 
> No motion without perpetual, apparently. ;)

No trolls without Australia.
Actually, I thought your idea of correcting the document had much merit, 
Phil. You and the other big shots here can get down to the task. I'll make 
the tea and correct the spelling. :-)