Groups > sci.electronics.design > #747535

Re: hilarious circuit

From	Bill Sloman <bill.sloman@ieee.org>
Newsgroups	sci.electronics.design
Subject	Re: hilarious circuit
Date	2026-09-10 23:45 +1000
Organization	A noiseless patient Spider
Message-ID	<117ucal$21isl$1@dont-email.me> (permalink)
References	(3 earlier) <3tmr9l5peaaekivf6v2p7lilkmmattjfvg@4ax.com> <117pnum$3ft31$2@paganini.bofh.team> <sd51al5kgbiil09r38jh5nkll8utve8udj@4ax.com> <117r0t4$rnn9$7@dont-email.me> <f363al5052mgpjmb405ooiji30p5i9tab6@4ax.com>

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On 10/09/2026 3:37 am, john larkin wrote:
> On Wed, 9 Sep 2026 17:12:30 +1000, Bill Sloman <bill.sloman@ieee.org>
> wrote:
> 
>> On 9/09/2026 9:12 am, john larkin wrote:
>>> On Tue, 8 Sep 2026 19:33:44 -0000 (UTC), Cóilín Nioclásín Glostéir
>>> <thanks-to@Taf.com> wrote:
>>>
>>>> John Larkin wrote:

<snip>

>> A data sheet that doesn't set an upper limit on popcorn noise (1/f or
>> flicker noise) is effectively warning you that the device generates a
>> lot of it.
> 
> Data sheets often hide part defects. Deliberately.
> 
> Test stuff that really matters.
> 
> Does popcorn noise still happen? I think it was caused by oxide
> contamination and that's been fixed. Popcorn is distinct from 1/f.

I thought that way until 1987, until I swapped out a 741 op-amp (which 
doesn't have a 1/f noise spec) in favour of a marginally more modern 
part that did.

The GaAs crystal puller it was controlling went from bang-bang operation 
- full on for about 30 seconds then off for about 60 seconds - to 
running quietly at about 30% of full output. There was a about 30 kW of 
heating involved, and it took about a day and half to pull a crystal, so 
the operators who had to baby sit the machine for the whole period were 
a lot happier.

My guess is that a lot of what was being packaged up and sold as 741s 
were actually better parts that had failed their 1/f noise screening.

Popcorn noise is a sort of 1/f noise. There are apparently others.

Regular noise is an aspect of thermodynamics - entropy and disorder. If 
you let unintended  impurities get into your thin base layer, and they 
move around you've got a different kind of noise source.

The relevant theory talks about a drunkard's walk, which is about a 
graphic as "pop-corn noise".

https://en.wikipedia.org/wiki/Random_walk

-- 
Bill Sloman, Sydney

Thread

hilarious circuit john larkin <jl@glen--canyon.com> - 2026-09-05 10:17 -0700
  Re: hilarious circuit Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2026-09-05 18:37 +0000
    Re: hilarious circuit john larkin <jl@glen--canyon.com> - 2026-09-05 12:18 -0700
  Re: hilarious circuit Jan Panteltje <alien@comet.invalid> - 2026-09-06 07:28 +0000
    Re: hilarious circuit Kragen Javier Sitaker <kragen@canonical.org> - 2026-09-06 17:55 -0300
      Re: hilarious circuit john larkin <jl@glen--canyon.com> - 2026-09-06 14:37 -0700
        Re: hilarious circuit Cóilín Nioclásín Glostéir <thanks-to@Taf.com> - 2026-09-08 19:33 +0000
          Re: hilarious circuit john larkin <jl@htigct.com> - 2026-09-08 16:12 -0700
            Re: hilarious circuit Bill Sloman <bill.sloman@ieee.org> - 2026-09-09 17:12 +1000
              Re: hilarious circuit john larkin <jl@htigct.com> - 2026-09-09 10:37 -0700
                Re: hilarious circuit Bill Sloman <bill.sloman@ieee.org> - 2026-09-10 23:45 +1000
                Re: hilarious circuit john larkin <jl@glen--canyon.com> - 2026-09-10 07:03 -0700
                Re: hilarious circuit Bill Sloman <bill.sloman@ieee.org> - 2026-09-11 16:45 +1000
                Re: hilarious circuit Cóilín Nioclásín Glostéir <thanks-to@Taf.com> - 2026-09-11 19:10 +0000
          Re: hilarious circuit Cóilín Nioclásín Glostéir <thanks-to@Taf.com> - 2026-09-11 18:51 +0000
  Re: hilarious circuit someone <2a59d59e3809f827ce709d3815e3950eef4a6a93af5557a93a7fdfba71460843@example.com> - 2026-09-09 17:45 +0000
    Re: hilarious circuit Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2026-09-09 18:59 +0000

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