Path: ...!Xl.tags.giganews.com!local-2.nntp.ord.giganews.com!nntp.supernews.com!news.supernews.com.POSTED!not-for-mail
NNTP-Posting-Date: Mon, 10 Jun 2024 19:14:40 +0000
Subject: Re: A collection of monographs on high accuracy electronics
Newsgroups: sci.electronics.design
References: <33c76j1cr78uhuk3djabivck4gbpe4dq9i@4ax.com>
 <v44n6p$3l18b$1@news.eternal-september.org> <v44qqi$3lquc$3@dont-email.me>
 <v44r4j$3mhiv$1@dont-email.me> <f9fc6j9c24haru81rkduufhjur42vbr53f@4ax.com>
 <v45hct$3tldi$1@dont-email.me> <6djc6jhurdaoqkvgnp0rcb1f4tci4da5pm@4ax.com>
 <c54cea67-c288-c6f7-e1fc-edade2f4b5e5@electrooptical.net>
From: Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net>
Message-ID: <5a46f302-382b-12de-f41d-61335179fe63@electrooptical.net>
Date: Mon, 10 Jun 2024 15:14:40 -0400
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101
 Thunderbird/91.0
MIME-Version: 1.0
In-Reply-To: <c54cea67-c288-c6f7-e1fc-edade2f4b5e5@electrooptical.net>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit
Lines: 122
X-Trace: sv3-D2PFEekb4sdsup8QMo8bIDCV24Sg56x/FaaxCbdDDAoADe8qMVulzrrSZx+Q2pUoNl0vNdGulkYECSk!uAtDtF71p95JMEWR/drFYTpur9UBcNwC4XnPLWKdkcJqlVDACvSwDUsyefbWb11AFr69i1ZI9i47!5Jxc7PNJItuMXN8GAM/Dx34p
X-Complaints-To: www.supernews.com/docs/abuse.html
X-DMCA-Complaints-To: www.supernews.com/docs/dmca.html
X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers
X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly
X-Postfilter: 1.3.40
Bytes: 5406

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.  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.

Twenty years ago I posted a brief derivation of the Johnson noise 
formula in the thread "thermal noise in resistors - Baffled!", as 
follows (with a couple of typos fixed).

> One good way of deriving the Johnson noise formula (the sqrt(4kT) thing)
> is from classical equipartition of energy. The stored energy in a
> capacitor is a single classical degree of freedom, and hence (when
> connected to a thermal reservoir, e.g. connected in parallel with a
> resistor at temperature T) has a mean energy of kT/2, and since the
> energy is CV**2/2, its rms noise voltage is sqrt(kT/C).
> 
> The noise bandwidth of a one-pole RC lowpass is (pi/2)*(3 dB BW) =
> 1/(4RC). Therefore, the noise power spectral density in the flatband is
> 
> p_N=(kT/2C)*(4RC) per hertz,
> 
> so setting p_N=C(e_N)**2/2, we get
> 
> (e_N)**2 = kT*4R
> 
> and
> 
> e_N = sqrt(4kTR) per root hertz.
> 
> This is the same noise that correlated double sampling in CCDs was
> designed to deal with. The advantage of this way of looking at it is
> that the resistor doesn't have to be linear--CMOS reset switches behave
> the same way.
> 
Cheers

Phil Hobbs



-- 
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com