On 2005-10-20 01:56:05 +1000, "Meindert Sprang"
said:

"John Proctor" wrote in message
news:2005101923295216807%lost@nowhereorg...
Don't forget that the LED is a current device. By that I mean light
output is a function of forward current. Hence to get even illumination
from multiple LEDs it is imperative that each LED be driven via a
current regulated source. It is not sufficient to parallel them up in
series with a dropping resistor.

Indeed. It's better to connect them in series (3 x 3V) and regulate the
current though that. Needs only one regulator.

Meindert

Unfortunately that approach does not allow for component spread.
Statistically a batch of random LEDs will exhibit a reasonable spread
in current to deliver equivalent luminosity. This is where the problem
lies with using LEDs for backlight on displays etc. Where the
illumination level must be even individual regulators are a must. In
the case of marine lighting where you are mearly interested in the
agregate light output a series connected string and regulator will
suffice.

--
Regards,
John Proctor VK3JP, VKV6789
S/V Chagall