Integrated circuits, resistors, capacitors





27
Jan

LED polarity marking — not?

Normally, I thought LEDs had the flat side on the cathode (like the stripe
on a conventional diode).

Yesterday I found some (Digi-Key Part P410-ND) that have the flat side on
the anode (both in real life and in the diagram on the Digi-Key catalog
page).

How common is this?

Like other LEDs, these still have the anode lead longer than the cathode.
But once you cut the leads, that feature is of course lost.

Incidentally, these P410-ND LEDs are a high-brightness type that work very
well in making POV displays (showing letters in the air as you move it past
you).  They are quite visible with just 2 mA of drive current.

posted by admin in Uncategorized and have Comments (3)






3 Responses to “LED polarity marking — not?”

  1. admin says:
    January 27 at 5:18 pm

    In article <xRsej.41511$_m.12…@bignews4.bellsouth.net>,

     "mc" <l…@www.ai.uga.edu.for.address> wrote:
    > Like other LEDs, these still have the anode lead longer than the cathode.
    > But once you cut the leads, that feature is of course lost.

    …

    What about the guts? Normally the cathode is the big hunk of metal and
    the anode is the small hunk of metal, looking inside the epoxy.

    –
    Cats, coffee, chocolate…vices to live by

  2. admin says:
    January 27 at 5:18 pm

    "Ecnerwal" <LawrenceSM…@SOuthernVERmont.NyET> wrote in message

    news:LawrenceSMITH-1A8EB4.13414301012008@news.verizon.net…

    > In article <xRsej.41511$_m.12…@bignews4.bellsouth.net>,
    > "mc" <l…@www.ai.uga.edu.for.address> wrote:

    >> Like other LEDs, these still have the anode lead longer than the cathode.
    >> But once you cut the leads, that feature is of course lost.
    > …

    > What about the guts? Normally the cathode is the big hunk of metal and
    > the anode is the small hunk of metal, looking inside the epoxy.

    Right, the "guts" were not reversed… if you line up an old and a new LED
    together by polarity, they have the "guts" in the same direction, but the
    flat sides are opposite.

  3. admin says:
    January 27 at 5:18 pm

    On Tue, 01 Jan 2008 18:41:44 GMT, the renowned Ecnerwal

    <LawrenceSM…@SOuthernVERmont.NyET> wrote:
    >In article <xRsej.41511$_m.12…@bignews4.bellsouth.net>,
    > "mc" <l…@www.ai.uga.edu.for.address> wrote:

    >> Like other LEDs, these still have the anode lead longer than the cathode.
    >> But once you cut the leads, that feature is of course lost.
    >…

    >What about the guts? Normally the cathode is the big hunk of metal and
    >the anode is the small hunk of metal, looking inside the epoxy.

    Not a reliable "indicator". Super-bright reds are the opposite.

    Best regards,
    Spehro Pefhany
    —
    "it’s the network…"                          "The Journey is the reward"
    sp…@interlog.com             Info for manufacturers: http://www.trexon.com
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