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From: "Don" <g@crcomp.net>
Newsgroups: sci.electronics.design
Subject: Re: CoB LED filament analysis
Date: Sun, 26 Apr 2026 02:18:41 -0000 (UTC)
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ehsjr <ehsjr@verizon.net> wrote:
> On 4/25/2026 6:56 PM, Don wrote:
>> john larkin wrote:
>>> Don wrote:
>>>> Don wrote:
>>
>> <snip>
>>
>>>> Game over. Lessons learned:
>>>>
>>>> 1. Pease hated solderless breadboards for a good reason: they introduce
>>>>     stray capacitance. After the solderless breadboard is removed the
>>>>     filament's current curve reverts to its true form with voltage and
>>>>     current in phase.
>>>
>>> 10 pF maybe. A million times less than would explain what you are
>>> seeing.
>>>
>>> But yes, the plastic solderless things are awful.
>>>
>>> https://www.dropbox.com/scl/fi/pk2t79ipe26c62lw9xi82/Z412_Proto.JPG?rlkey=jypa4wdmgqsvwu0l51rx1x445&raw=1
>>
>> Bravo! If I remember correctly, you use a dental drill? My own freehand
>> dremel on copper isn't nearly as straight. Perhaps my new milling table
>> [1] will help.
>>      My media tends towards universal board. As an artiste associate,
>> appreciate my abstract art arrangement:
>>
>>      <https://crcomp.net/ledfilament/circuit.png>
>>
>> Note how voltage and current perfectly align after the solderless
>> protoboard is swapped out and replaced by my abstract art arrangement:
>>
>>      <https://crcomp.net/ledfilament/curveprobe3.png>
>>
>> There's little, if any, wriggle room for the phase anomaly to caused by
>> anything other than stray capacitance from the solderless breadboard.
>
> How about parallel and/or series R? Gunk between breadboard contacts
> or oxidized/loose contacts?

Yes! All of the above plausibly contribute to capacitive current curve
corruption caused by my real world breadboard /system/, so to speak. 
    You get it. It's critical to understand the difference between the
idealized stray capacitance of 2, 3, or 5 pF, as mentioned in 
TROUBLSHOOTING ANALOG CIRCUITS by Pease and my breadboard system's 
real world stray capacitance. 
    Although idealized components make theory easier to comprehend, it
can be a mistake to assume idealized values in the real world. With this
very project, for instance.

Danke,

--
73, Don, WD7Q                                             veritas    _|_
                                                          liberabit   |
https://www.qsl.net/wd7q                                  vos         |