The apparent brightness is the same if the average current is the
same. Pulsing them does not make them look brighter.

This assertion is based on an experiment I did today.

I ran two identical red LED's (automotive brake-turn parts if it
matters, LiteOn LTL 912-VRKSA), one with DC current and the other
getting pulses of 10X that current with a 10% dutycycle so the
average current was the same.

I ran this at a variety of currents and frequencies. In every case,
the LED's looked identical and indistinguishable unless the frequency
was low enough so there was noticable flicker. At 40 Hz, where there
was noticable flicker, the pulsed LED didn't look any brighter but it
was certainly more irritating.

On Mon, 6 Dec 2004 16:40:19 -0000, "Leon Heller"
wrote:

The best way to get a lot of light out of LEDs is to
pulse them at a relatively high rate putting lots of current through them.