|
| News | Electronics Museum | Articles | Video | About | Store | RSS | Contact |
| Solid State Indicators |
Light emitting diodes were developed as a cheap, reliable solution for both indicator lamps and character displays, and were compatible with the rapidly evolving transistor technology of the 1960s. Pioneering LED manufacturers include General Instrument, HP, Monsanto and Texas Instruments.
| Fairchild FLV Series | |
 |
Devices included in this entry: The FLV-100's 500ucd point light source was nearly useless as an indicator, so Fairchild released a modified version, the FLV-102. The FLV-102 is identical to the FLV-100 in every respect, with the exception that the clear red epoxy on the top of the leadframe has been replaced with a diffuse red epoxy blob, in a vain attempt to improve the visibility of the weak light emitted by the die. This reduced the viewing angle, the FLV-100 has a view angle of 80 degrees whereas the FLV-102 has a view angle of only 30 degrees. The light emitted by the FLV-102 ,at a partly 1mcd, is only marginally easier to detect than that emitted from a FLV-100 and both are easily drowned out by average incandescent lighting. |
| Dialco 521-9167 | |
 |
These later three-lead LED devices appear to be modeled heavily after the construction style of the FLV102 and other T-106 package LEDs. It is all in jest however, as the 521-9167 is not built on a T-106 carrier, instead a plastic casting designed to mimic the appearance of a ceramic T-106 has been used as this diode's base. The red lens is also plastic, and is almost surely cast separately from the rest of the diode and then affixed afterwards. It is unknown why a manufacturer would go to such lengths and expense to mimic the appearance of earlier FLV-style LEDs, even the third lead on the device is superfluous, as it serves no electrical function. The brightness on these devices is fairly acceptable, light output is about what one would expect from a mid-1970s 5mm LED. |
| N6L 002 (Unknown Mfr.) | |
 |
Here is a LED that in outward appearance appears nearly identical to the FLV102 and Dialco 521-9167 LEDs pictured above. This device is of much higher construction quality, its T-106 style package is bonded to a clear glass lens and it lacks the superfluous third lead of the 521-9167. The light output is vastly superior to the FLV102 and approaches that of a standard 5mm LED. The manufacturer of this part is unknown. |
| General Instrument MMH-321V | |
 |
These barely macroscopic components are individual LED dies used for manufacturing first-generation displays like the Monsanto MAN-1. The thumbnail image was taken at 30X magnification; the fine probe to the right of the dies is about three human hairs in width. Dies like this would have normally only been used internally by a display fabrication company, and were never intended to be sold to the general public. Multiple dies are attached to a conductive backing to form lines and characters, and an extremely fine wire is connected to the cross-shaped contact on the top of the die to complete the circuit. |
| Hewlett-Packard 1842-7329 | |
 |
We don't know much about this part, other than that it was made by HP and appears similar in outward appearance to the Monsanto MV2. The diode has the same gold plated metal can package and 'anvil head' style contact pad as the archetypal Monsanto MV2. Only when viewed under high magnification do significant construction differences begin to appear: the die in this LED has a substantially different top contact. Unlike the MV2, which has a simple circular contact, the 1842-7329 has a series of 'fingers' which extend into the GaAsP emitting section of the die. The fingers appear to do nothing to help the diode's brightness, as the 1842-7329 is just as dim as other diodes from this era. |
| Hewlett-Packard HLMP-DBxx Series | |
 |
Introduced in 1993, the Hewlett-Packard HLMP-DB00 and HLMP-DB15 are among a small number of commercially produced silicon carbide (SiC) blue light emitting diodes. The two devices appear to be internally identical, the only difference being that the -DB00 has a slightly milky, diffuse lens, while the -DB15 is water-clear. Two other HP SiC LED types are also known: a 3mm diffuse type and a 5mm diffuse RGB model with a SiC blue die. The part numbers for these devices are not currently known. |
| Monsanto MV1 | |
 |
The Monsanto MV1, released in 1969, is considered by most LED collectors to be the world's first production visible light emitting diode. As can be expected, the MV1 bears only a loose resemblance to a modern epoxy-packaged LED. The semiconductor material is packaged in a gold plated metal can, similar to the TO-5 can packages used for many transistors. There is no reflector as seen in later LEDs. The diode die is mounted directly to a characteristic 'anvil head' contact surface in the bottom of the package, a technique that can be seen in many first generation LEDs. Under magnification, the GaAsP emitting sector can be seen as a circular void surrounded by an upper contact that covers all of the unused space on the top of the die. As expected, the MV1 is a very dim light source, and is barely visible under normal indoor lighting. It should be noted that up until recently, many collectors falsely identified this device as a Monsanto MV2. This is inaccurate: the MV2, shown below, is a green-emitting LED device. |
| Monsanto MV2 | |
 |
The MV2 is Monsanto's first green LED, and was released as part of the same series as the MV1 shown above. This device has a totally unusual water-clear die, possibly made of silicon carbide, which emits a pale green light when energized. The die does not have a traditional ball bond and contact pad, the contact wire appears to be soldered or brazed directly to the surface of the die. The MV2 sold poorly when it was released; the light output from the device is so dim as to be nearly worthless, and the majority customers opted to purchase Monsanto's brighter MV1 LED instead. |
| Motorola TO-92 Package LED | |
 |
This device is a mundane red LED die in a strange enclosure: a standard TO-92 transistor package. Electronics lore states that Motorola made these parts-of-questionable-judgment under contract for use in camera rangefinders. The existence of such a device stands as a depressing reminder that, at one point in the not-so-distant past, it was actually economically viable to increase the gold content of your product by 50% if it would let you avoid changing your package tooling. |
| Nichia NSHU5x0E Series | |
 |
Devices included in this entry: |
| Soviet 3L341V | |
 |
The 3L341V is a rare example of a Soviet-made LED. Manufactured in 1989, the 3L341V appears to be standard GaP green chemistry, but is encased in a 1970s-style metal can package with gold leads. The included datasheet indicates that they emit no less than 0.15 microlumens, for implementations where a 0.1 microlumen LED just won't cut the mustard. Needless to say, you won't need special eye protection to handle them. |
| Three-Five Systems TLMP-9x10 Series | |
 |
Devices included in this entry: We have been unable to exactly date these LEDs, but would estimate their date of manufacture to be in the late 1980s based on their construction style. |
| Western Electric AC LED | |
 |
The Western Electric AC LED has two green dies of opposite electrical orientation, wired in parallel. The LED is normally operated at 60Hz, installed in a Western Electric Trimline telephone handset. This device has an unusual concave lens and large heatsink leads. |
| Western Electric Green LED | |
 |
Another model of Western Electric LED, these small devices were used in the handsets of various phones throughout the 1970s. Unlike the large Western Electric LED pictured above, these are DC devices, and contain only a single die. Western Electric's manufacturing excess is alive and well in this device, which features thick heavy gold leads and a flanged plastic package designed to fit in a 3mm LED socket. Western Electric also manufactured a red version of this part, which is identical in all respects other than the composition of the LED die. |
| Early Straight-Pin LED (Unknown Mfr.) | |
 |
A dead end in LED design, straight-pin LEDs are single lead devices that are designed to be mounted directly in a plated hole on a PCB. The single lead is bent and attached to a separate pad on the underside of the PCB, the LED casing mated to the plated PCB hole acts as the other electrical connection. We have no idea who manufactured this particular device, but suspect it was most likely produced by Motorola. |
| Early Red LED (Unknown Mfr.) | |
 |
Unfortunately, LEDs do not typically have part numbers printed on them. The breadth of unknown and unidentified LEDs is great, and this is yet another anonymous example. In construction this device appears similar to the Monsanto MV2, though the die is noticeably brighter. This device also has a significant reduction in gold content: the metal can of the MV2 has been replaced by a shallow metal base. The frosted epoxy construction makes this a much more usable indicator than the MV2, though it unfortunately prevents any microscopic examination of the die. |
| Early Green & Red LEDs (Unknown Mfr.) | |
 |
These unusual early LEDs are constructed on a disk of gold covered in frosted epoxy. The example on the left contains a standard early red die, similar in brightness to a Monsanto MV2. The rightmost example is a rare early attempt at making a usable green LED. The amount of light produced by this early green LED is far dimmer than even the MV2, and can only be seen in a darkened room. |
| Green Epoxy GaAsP LED (Unknown Mfr.) | |
 |
This strange device is exactly what it appears to be: a standard GaAsP red LED in a standard 5mm green epoxy case. It is unknown whether this device is a manufacturing error or a failed attempt at producing a new color. The device produces a pure red light, only slightly dimmed by the green lens. |
| Early Orange Epoxy LEDs (Unknown Mfr.) | |
 |
Devices included in this entry: |
| ©2000-2010 The Vintage Technology Association. All rights reserved. | Login |