Path: utzoo!censor!geac!torsqnt!lethe!yunexus!ists!helios.physics.utoronto.ca!news-server.csri.toronto.edu!bonnie.concordia.ca!thunder.mcrcim.mcgill.edu!snorkelwacker.mit.edu!apple!usc!samsung!rex!uflorida!cs.fau.edu!terryb From: terryb@cs.fau.edu (terry bohning) Newsgroups: sci.electronics Subject: Re: LED history ? Message-ID: Date: 23 Jan 91 05:37:52 GMT References: <1962@atlas.tegra.COM> Sender: bbs@cs.fau.edu (Waffle BBS) Organization: Florida Atlantic University Lines: 22 vail@tegra.COM (Johnathan Vail) writes: > On a related note: I was working on a CD player and on the circuit > board was a normal looking glass diode, cathode band and all, that lit > up red. It wasn't an indicator, and had a normal D number like the > other real diodes on the board. > > Was the light emitted a side effect of the diode? > > Was it a special LED in this package for use to frop a certain voltage > or something? LEDs also make good low-voltage voltage regulators using the forward drop. I used one many years ago in a circuit. The ones I had didn't have a forward drop that was very consistent unit to unit, tho'. Forward voltage ranges from about 1 to 2 V as I recall, depending on type and color. This is great, tho', since zeners of this low value are hard to come by. "The forward conduction characteristic of the LED displays a much sharper knee than ordinarily obtained from forward-biased silicon junction diodes...Generally, satisfactory regulating action begins when the LED is just visible in the dark." From: "Regulated Power Supplies", Irving M. Gottlieb, Howard W. Sams, 1981, 3rd ed.