Path: csiph.com!eternal-september.org!feeder.eternal-september.org!nntp.eternal-september.org!.POSTED!not-for-mail
From: "Don" <g@crcomp.net>
Newsgroups: sci.electronics.design
Subject: Re: A fully floating BJT-based LED current driver
Date: Fri, 10 Apr 2026 03:24:31 -0000 (UTC)
Organization: A noiseless patient Spider
Lines: 68
Message-ID: <20260409c@crcomp.net>
References: <6tltskde2lkpbo4s5g44ujar7b2tttk0k9@4ax.com> <18a493794d041b26$1$2982030$4226dc73@news.newsgroupdirect.com> <20260409a@crcomp.net> <vjgftk1k5t0ukin3sftgfp9mjpqgtbegkk@4ax.com> <5sdgtkl2jcbqq1l28a90742i1d4dbkdb7t@4ax.com>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Injection-Date: Fri, 10 Apr 2026 03:24:32 +0000 (UTC)
Injection-Info: dont-email.me; posting-host="c1cfed1270e34454b7b5bb050e3a60d6"; logging-data="861288"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX19rDiSSHxLCR/fPffr6ssug"
Cancel-Lock: sha1:DMN9wqfEDcfvDzDcVc71q3af6OU=
Xref: csiph.com sci.electronics.design:742875

john larkin <jl@glen--canyon.com> wrote:
> On Thu, 09 Apr 2026 16:16:34 +0100, JM
> <sunaecoNoChoppedPork@gmail.com> wrote:
>
>>On Thu, 9 Apr 2026 09:17:04 -0000 (UTC), "Don" <g@crcomp.net> wrote:
>>
>>>Allow me to transition this topic to 120 VAC LED COB filaments. This
>>>picture shows such specimens, with the topmost powered-on and the
>>>bottommost powered-off:
>>>
>>>  <https://crcomp.net/led/accob.png>
>>>
>>>The protoboard's black wire connects to 120 ACV Line while its white
>>>wire connects to Neutral. My goal is to discover the silicon secrets
>>>in such a simple filament.
>>
>>Look up NUD4011 and it's alternatives, it'll be something that
>>operates in a similar fashion.
>
> That would need the NUD chip and a bridge rectifier and maybe a
> resistor and a  varistor.
>
> I'd expect simpler and cheaper in that tiny gadget.
>
> What do you call that axial lead LED thing?

It's an AC Chip-on-Board (COB) LED filament. After a lifetime of using a
resistor to carefully control current through an LED to keep it from
burning up, it sort of shocked me, so to speak, to see an LED directly
connected to Line and Neutral.

    What are CoB LEDs?

    LUXEON CoB Finder

    A CoB LED (or chip-on-board LED) is a single device with 
    many LED chips mounted on a thermally efficient substrate 
    placed below a uniform phosphor coating.

    Anyone who walks through a store or home with recessed or 
    track lighting likely experiences light from a chip-on-board
    LED (CoB). CoBs are widely used because they emit a bright
    white light output from a compact light source and are very
    efficient in a broad range of applications.

    So what is a CoB LED, and how is it different from other 
    types of LEDs?

    CoB (chip-on-board) refers to the way in which the LED unit is
    constructed. The basic elements of white CoB LEDs are:

    An electrical power supply to provide the energy to drive the LED
    The light-emitting chip or ‘die’. This is sometimes referred to as
    the blue light pump, and is made of a semiconductor material, 
    indium gallium nitride (InGaN), which emits blue photons when 
    energized. A phosphor coating which converts the blue light to
    white. The chemical composition of the phosphor is controlled to
    produce light of a specific color temperature.
    
    <excerpt>
    
    <https://lumileds.com/technology/led-technology/understanding-cob-leds/>
 
-- 
73, Don, KB7RPU                                           veritas    _|_
                                                          liberabit   |
https://www.qsl.net/kb7rpu                                vos         |