LED polarity marking -- not?

Jan 01, 2008 3 Replies

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.


...

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

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.

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

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