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VINTAGE HEWLETT-
PACKARD 4-DIE LEDs
Manufactured by Hewlett-Packard (www.hp.com)
Last updated 10-26-11
These are unique, vintage LEDs sent to me by J.J. in late-October 2011.
They differ from normal, 5mm (T1ž) through-hole LEDs in two significant ways.

1: They have a flat, lensless design and their transparent epoxy cases are tinted in the emitted color so you could tell them apart in your parts bin.

2: They have not one die, and not two -- but FOUR (4) dice to help boost their otherwise somewhat feeble light output.

The four dice appear to all be connected in series; hence these LEDs have a significantly higher Vf (forward voltage) than is usually found with single-die LEDs using the same operating chemistry.

You will note that these LEDs have three leads -- the center lead is there to allow you to operate the LED with only two dice; you will however require another ballast resistor otherwise you'll very likely fry them from excessive If (forward current).

These are the vintage HP 4-die LEDs, in red, amber, and yellow-green.

Spectrographic analysis of the red one.

Spectrographic analysis of the red one; spectrometer's response narrowed to a band between 630nm and 670nm to pinpoint peak wavelength, which is 642.10nm.

As you can see, this one broke already; one of the leads broke off so only two of the dice are illuminated.

This photograph shows the lead and a segment of epoxy encapsulant that snapped off; this is the first vintage LED to have ever become broken while in my custody.

I normally "baby" vintage and antique LEDs, so it is uncertain why this one "went".

Spectrographic analysis of the amber one.

Spectrographic analysis of the amber one; spectrometer's response narrowed to a band between 565nm and 615nm to pinpoint peak wavelength, which is 584.980nm.

Spectrographic analysis of the yellow-green one.

Spectrographic analysis of the yellow-green one; spectrometer's response narrowed to a band between 540nm and 590nm to pinpoint peak wavelength (there are two peaks actually), which are 564.10nm and 568.92nm.

Do you manufacture or sell an LED flashlight, task light, utility light, or module of some kind? Want to see it tested by a real person, under real working conditions? Do you then want to see how your light did? If you have a sample available for this type of real-world, real-time testing, please contact me at ledmuseum@gmail.com.

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