alan smith wrote:
> But what about driving the parallel string with just a
> simple transistor?  Since the LED's are being
> modulated  of sorts by the PWM signal, the transistor
> should just act as a driver?

The problem is that the voltage drop accross each LED is a little different
at the same current.  Since LED's are diodes, a small change in voltage can
cause a large change in current.  Also, the voltage drop decreases with
temperature.  The LED that is taking most of the current will get warmer,
causing it to take more current, causing it to get warmer...


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