On Wed, 13 Jan 2010 19:15:56 -0800, John Larkin
wrote:



If you use 14 volts to run a 3.4 volt LED, with a dissipative system,
the efficiency is always around 24%. Different circuits just move the
heat around.

With pairs of LEDs in series, efficiency becomes 6.8/14 = 48%.

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Yes, but if one fails shorted the second one will follow soon after if
its If(max) is exceeded, while if one fails open two will go out so
you're trading efficiency for reliability.

JF