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- Path: sparky!uunet!sun-barr!cs.utexas.edu!rutgers!bobsbox.rent.com!s4mjs!kc2wz!bob
- From: bob@kc2wz.bubble.org (Bob Billson)
- Newsgroups: sci.electronics
- Subject: re: The first LED's?
- Message-ID: <110@kc2wz.bubble.org>
- Date: 15 Aug 92 19:47:29 GMT
- References: <1992Aug7.104606.8663@iccgcc.decnet.ab.com>
- Distribution: na
- Organization: Color Computer 3: Tandy's 'game' machine
- Lines: 29
-
- moskin@iccgcc.decnet.ab.com says:
- >>From "LED Circuits and Projects", by Forrest M. Mims, III, 1973:
- >
- >> In recent years, a family of semiconductor devices capable of
- >> emitting visible and infrared light has become available.
- >> Semiconductor light emission was first discovered in 1907 by
- >> H.J. Round, but it was not until 1960 that efficient light
- >> generation in a semiconductor was obtained.
- >>
- >
- > I heard once that the early semiconductor diodes used in computers
- >had clear casings but they were changed to opaque because they glowed red
- >and alarmed people who didn't know that this was normal. Could this be
- >considered a Light Emitting Diode? Can anyone verify this story?
-
- Or perhaps it was because the transistors were acting like phototransistors.
-
- I have made phototransistors in a pinch by carefully removing the top of a
- metal cased NPN transistor (such as a 2N2222). The exposed semiconductor
- is sensitive to light. To protect the semiconductor, I would put a drop of
- clear glue or expoy over it. Worked out reasonably well for a couple of
- situations.
-
- Bob
- --
- Bob Billson, KC2WZ | internet: bob@kc2wz.bubble.org
- | kc2wz@amsat.org
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- C code. C code run. Run code run...<please!>
-