[dorkbotpdx-blabber] [GroupOrder] order goes out monday feb 23. guest star: sure electronics

[Daniel Johnson]

> Calculate the resistor value as:
>  R = (Vdd - Vf) / If
> where Vdd is the supply voltage (5V for Arudino), "Vf" is the "forward
> voltage" of the LED (see the spec -- it varies by color; ~2.0V for the
> LE-DS151), and "If" is the desired "forward current", which will depend on
> the desired brightness.
> So, the resistance needed to deliver 10mA to the Red LE-DS151 would be:
>  R = (5V - 2V) / 10mA = 300ohm

The packages with free resistors don't say what the value of the free
resistor is.  I had trouble reading the color codes off of the
pictures too.