[Laser] Some History of the ~100 year old LED !!

[laser]

----- Original Message ----- 
From: "Dave" <wa4qal at ix.netcom.com>
To: <laser at mailman.qth.net>
Sent: Friday, November 19, 2010 11:52 AM
Subject: [Laser] Some History of the ~100 year old LED !!

> Don't forget that H. J. Round discovered the LED effect in Carborundum in
> about 1906 (published in "Electrical World" in the 9 February 1907
> edition):
>
> http://en.wikipedia.org/wiki/H._J._Round
>
> So, that makes LEDs well over 100 years old.
>
> Dave
> WA4QAL
> ______________________________________________________________

Thank you.  That's the guy I was looking for!!!  I was having a problem
trying to get 100 years from 1927 and knew I was leaving something out as I 
remember doing this research once before and found out the LED was indeed 
over 100 years old.

Round is mentioned in the first couple lines of the PDF article that I 
quoted before:

http://www.orc.soton.ac.uk/fileadmin/downloads/100_years_of_optoelectronics__2_.pdf

It's been a while since I read that article and forgot about Round.  But 
he's the guy I was looking for as I KNEW the LED was over 100 years old. 
And he's the guy that reported exactly what I remember seeing when playing 
around with biased carborundum detectors and crystal set radio receivers.

From: http://en.wikipedia.org/wiki/H._J._Round
=====
"In some later experiments with cat's whisker detectors using a variety of
substances, he passed current through them and noticed that some actually
gave off light - the first time a light-emitting diode had been seen. Round
reported this in the February 9, 1907 edition of Electrical World. This
is the first known report of the effect of the light-emitting diode.

  To the Editors of Electrical World:
      SIRS: During an investigation of the unsymmetrical passage of current
through a contact of carborundum and other substances a curious phenomenon
was noted. On applying a potential of 10 volts between two points on a
crystal of carborundum, the crystal gave out a yellowish light. Only one of
two specimens could be found which gave a bright glow on such a low voltage,
but with 110 volts a large number could be found to glow. In some crystals
only edges gave the light and others gave instead of a yellow light green,
orange or blue. In all cases tested the glow appears to come from the
negative pole, a bright blue-green spark appearing at the positive pole. In
a single crystal, if contact is made near the center with the negative pole,
and the positive pole is put in contact at any other place, only one section
of the crystal will glow and that same section wherever the positive pole is
placed.

      There seems to be some connection between the above effect and the
e.m.f. produced by a junction of carborundum and another conductor when
heated by a direct or alternating current; but the connection may be only
secondary as an obvious explanation of the e.m.f. effect is the
thermoelectric one. The writer would be glad of references to any published
account of an investigation of this or any allied phenomena.

      New York, N. Y.

      H. J. Round"
=====