Lamps & LEDs

When a lamp is to be operated at a voltage other than the rated or design voltage, the rerated lamp specifications Should be calculated to determine suitability for the user's application. The following formulas assist in predicting the rerated effect on luminous intensity, endurance and current. Results are most reliable for applied voltages close to the rated voltage.

Light emitting diodes (LEDs) operate at relatively low current and DC voltage levels and have virtually unlimited service life. Their characteristics do not change significantly with age, and they are not easily damaged by shock or vibration. The light emitted is of relatively low intensity. A variety of NKK's switches and indicators are offered with red, green, yellow, or bicolor (red/green) LEDs. They are used with red, green, or yellow lenses. Most of the LEDs used in our products are single element and usually require a ballast resistor connected in series with the LED. Inaddition, we offer 5-, 12-, and 24-volt lamps with internal resistors in the YB series.

Lamp life is determined in a laboratory environment where conditions are near perfect. Actual applications, unlike the test environment, involve many factors which can greatly affect the values listed in lamp specifications. Of all the operating characteristics, lamp life is the least predictable. The lamp filament must deteriorate to produce illumination, and actual life is a function of this unpredictable rate of deterioration. Thus, exact life performance cannot be determined for any incandescent lamp under any set of conditions. Lamps perform at their maximum when used at their rated AC voltages or below. There are many known conditions or factors thataffect lamp life. Using the lamp in abusive environments such as high ambient temperatures, high shock and/or vibration, multiplexing lower than 400Hz, constant illumination, and DC voltage accelerates deterioration of the Tungsten filament.

Neon lamps are low-current, long life sources limited by the high ionization voltage of neon (e80 volts) for use in line voltage circuits. A series resistor is required in all neon lamps for current limiting. Larger lamps often include an integral resistor sized for a specific voltage. Neon lamps glow with a low intensity, amber light. Bright light and vivid colors are not obtainable with neon lamps. Their typical1.5mA current drain, better than 25,000-hour service life, and good resistance to shock and vibration make them an excellent alternative in many line voltage applications. For best visibility they should be used with clear lenses and diffusers. Other suitable colors are red, orange, yellow, or white.

For best results and safe use of the LEDs, an appropriately valued ballast resistor should be used. Without the ballast resistor, the LED will be damaged or destroyed. The resistor value can be calculated by using the formula shown here. Watt recommendations provide a margin to reduce heat rise and increase life.