> BTW, set your PSU voltage to match series forward voltage
> of the LEDs. For example, a yellow is typically around 2.1V,
> so you could put 3 in series on ~ 6.5V supply with no current
> limiting resistor, makes life simpler (no heat) and a little cheaper
>
This sounds like it could get you into trouble if temperature or
something changes the LED voltages a little.  If your supply doesn't
track the current will change wildly.  You really ought to have some
ballast resistance, or use a current driver.

Sherpa Doug

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