LED Question

On a sunny day (Sat, 27 Dec 2008 01:35:47 -0800 (PST)) it happened Efthimios wrote in :

LEDs will operate at very low currents, but then give simply less light.

I have used ordinary LEDs at 1ma (had to sheild them from ambient light) high efficiency LEDs may work for you.

use several ne2 indicators wired in series (keep adding until the glow is bright enough) they need about 90v each.

I am a bit new to this. What is ne2????

E

An NE2 is a small neon bulb. A common application for this device is the ON indicator of so-called power strips.

indicator of so-called

Don't they mostly use those newfangled transistorized NE2H bulbs?

;-)

Best regards, Spehro Pefhany

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Heh! Might be so, I guess, judging by other similarly absurd marketing hypes foisted on consumers from all directions. (Anyone remember "The Goon Show" radio program? One episode parodied current advertisments: Genuine, instant water; just add water and stir; accept no substitute.)

Except for three of the tens of powers strips in use around my house, all are pre-1990. At least half of these old ones - possibly more - have a neon ON indicator; of those neons, only four (that I can recall) still light up; of those that still light up, only one does *not* have the sick-flicker malady.

I know of single-chip LEDs (voltage drop at current as low as I propose beinmg near/under 3 volts) good at fractional milliamp:

1. Green ones with nominal wavelength less than 545 nm, as in many with "InGaN" chemistry. Expect quite a few of those to be plenty bright at half a milliamp or less. More-prime examples are Nichia's "roughly-1-year-marketed" (as best as I know from my experience) NSPG-510AS, NSPG-520AS, NSPG-320CS, and NSPG-F50AS - glowing about as brightly at maybe 1/8 or 2-tenths of a mA as green LEDs as best as maybe as late as mid 1980's produced!
2. There are modern ultrabright red LEDs that are extremely efficient and "fairly maintaining" their efficiency to impressively low currents at which many LEDs "underperform". One is most rated at least 2,000 mcd and having nominal wavelength of

660 nm. 2nd is Nichia's NSPR-510AS. 3rd is anything else at least as bright and red in color.

1. "Low Current Red" - not especially bright even by mid-1980's standards or maybe even early-1980's standards at 20 mA, but dimmed less than other LEDs are when current is decreased to the "1-mA to fractional-mA ballpark". Look for peak wavelentths 690, 697, or 700 nm, as well as voltage drop maybe .2 volt higher than usual for then-older technology rede LEDs at same current, and also millicandela a bit on the high side for red LEDS of chemistry that old, first-exceeded "for red" at 20 mA by "high efficiency red" - which is longest-widely-done wavelength (peak in

630's of nm, with "dominant wavelength" [color specification] mid-620's at moast) for GaAsP on GaP substrate (as opposed to GaAs for "old fashioned red").

The 1970's-established "low current red" LED has GaP substrate and chemistry, as well as at least a little notably significant doping with ZnO to accentuate broadband red/reddish emission from a yellow-green-favoring basic-chemistry.

- Don Klipstein ( snipped-for-privacy@misty.com)

indicator of so-called

NE-2H is a variant from NE-2 having voltage drop a little greater, design current a few times as great, significantly shorter lifetime (still at least a few years at 120 VAC with 33k resistor),...

NE-2H has pure neon, and regardless of "favored current density" is brighter to human eyes. NE-2 and most usual variants of NE-51 (I hope I got that right) have neon-argon mixture around 9.5%-neon-.5%-argon - favoring easier starting and voltage drop several volts less - but lower luminous efficacy, since argon in such a mode of a "glow lamp" detracts from the visible-spectrum wavelengths of neon towards similar near-infrared wavelengths of argon, but for "cathode/negative-glow" in glow lamps argon detracts less from one single yellow wavelenth of neon as well as produces awfully visible visible contribution from argon. That is why NE-2 glow lamps are a bit more yellowish than the somewhat-bit-more-reddish NE-2H glow lamps.

- Don Klipstein ( snipped-for-privacy@misty.com)

Here is a thread from last month:

*-*-*-dark-adapted+15.uA+1.5.uA+zz-zz+qq+Avago-*-*-*-LEDnews: snipped-for-privacy@4ax.com

Here is a post on asking smart questions:

*-*-*-*-*-*-nicer-framework-*-*-*-*-*-*+zz-zz+qq+tell-the-_whole_-storynews:vuSdnT_wZvsbQKPUnZ2dnUVZ snipped-for-privacy@web-ster.com