LED polarity marking -- not?

[mc]

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.

 

[Ecnerwal]

In article <xRsej.41511$_m.12375@bignews4.bellsouth.net>,
"mc" <look@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

 

[mc]

"Ecnerwal" <LawrenceSMITH@SOuthernVERmont.NyET> wrote in message
news:LawrenceSMITH-1A8EB4.13414301012008@news.verizon.net...

In article <xRsej.41511$_m.12375@bignews4.bellsouth.net>,
"mc" <look@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.

 

[Spehro Pefhany]

On Tue, 01 Jan 2008 18:41:44 GMT, the renowned Ecnerwal
<LawrenceSMITH@SOuthernVERmont.NyET> wrote:

In article <xRsej.41511$_m.12375@bignews4.bellsouth.net>,
"mc" <look@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"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com