Dictionary of Technical Terms for Engineers and Technicians
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Light Emitting Diodes. [LED] A PN-junction diode that emits visible light when it is forward biased. LEDs are solid-state semiconductor light sources, LED Manufacturers.
Light Emitting Diode Symbol
Depending on the material used to make the diode, the light may be red, green, or amber, [LED Semiconductor Material vs. LED Color].
LEDs may be uni-color, bi-color, or tri-color, in either through-hole or a Surface Mound Device [SMD].
Packages. Standard sizes for thru-hole [radial] devices are;
T-1 [3mm] and T-1 3/4 [5mm].
Round lens Sizes; 3mm, 5mm, 8mm, 10mm, 20mm;
Rectangular lens sizes; 2x5x7mm;
OVAL lens sizes; 4mm, 5mm.
Metal packages are also common to include 2-lead TO-46 packages for two terminal LEDs and 3-lead TO-46 packages for either 3-leaded LEDs or a pair of LEDs with a common connection.
Tri-Color LED Package
Manufacturers of Multi-Colored LEDs, Visible Spectrum Graph
Through-Hole LED, Leaded LED
The Cathode is the short lead, and the Anode is the long lead [positive part of circuit] for thru-hole devices.
Chip LED. A surface mount LED
Electrostatic Discharge. LEDs are semiconductor diode and can be damaged by static electricity and surge currents. Refer to the Dictionary of ESD Terms
Circuit Board Indicator. Stacked LED modules used to mount next to a panel, so only the LED lens protrudes through the panel. The supporting module holds the LEDs, forms the leads of the LED and provides spacing between the individual LEDs. |
 LED |
A Circuit Board Indicator module may hold one or more individual LEDs. A Circuit Board Indicator differs from a panel mount because it does not attach to a panel. Another term used in this regard is Housing LED, perhaps because the LEDs are installed in a housing.
High Brightness. Text in review. There is also a listing of Super Bright LEDs [Manufacturers and Vendors].
LED Display. A component or package that contains more than one LED, sometimes arranged into a symbol or shape. A part that contains a number of LED components.
Lens. The component on the LED which is used to transmit or focus the light emitted from the LED. The lens might be clear, diffused or tinted and made of glass or plastic.
Panel Mount / Bulk-Head Mount LED
Panel Mount LED. Also called a Bulk-Head Mount LED is an LED assembly at attaches to a panel in a number of different ways. The two most common methods of attaching to a panel are snap-on and screw-on. Normally the snap-on type places an LED within a plastic case. The plastic case is compressed when installing, than allowed to reform to its normal size when inserted into the cut-out in the panel. The screw-on mounting method [shown in the attached graphic] mounts to a panel just as many connectors do, by securing a nut to the threads affixed to the base of the LED. A few examples of Panel Mount LED Styles are provided in the reference link.
LED Display Manufacturers and companies producing LED Displays.
7-Segment Display. Is an array of LEDs laid out in a pattern in the shape of an eight as shown by the graphic in the side-bar. For more information on how to drive a 7-Segment Display, refer to the 7-Segment Driver IC Schematic which details the operation of an IC driver chip. |
 7-Segment Display |
 Hexadecimal Display | Hexadecimal Display. Is a array of LEDs laid out in a pattern in the shape of an eight as shown by the graphic. However the array used with the Hexadecimal Display is more detailed than the 7-segment display, using more light emitting diodes. BCD to Hex Displays; 4N51, 4N52, 4N53 and 4N54. Note only the 4N54 produces all the hex values. A true table is provided with the 4N54 description. |
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