On Sun, 09 Jun 2013 12:38:47 -0700, jfitch wrote:

On Sunday, June 9, 2013 10:15:07 AM UTC-7, Bill D wrote:
If you plan to use the gliders 12V bus, the LED's need the resistor.
(FWIW, non-rechargeable lithium cells output 3.7V which is just right
for an LED without resistor as millions of key-ring flashlights show.)


An LED is a diode junction, forward voltage is around 0.7 to 1.1V
typically. 3.7V will make a single diode glow very brightly for a very
short time. Cheap flashlights usually have 3 or 4 LEDs in series to
accommodate the higher voltage.

Look at the maximum current rating of the LEDs, assume the LED has no
resistance and calculate the series resistor value from R = V/I where I
is the maximum rated current for the LED in amps, V is the supply voltage
in volts and R is the inline resistor in ohms. Round the resistor UP to
the next highest standard resistor size and fit that resistor size in
series with each LED.

This will give near maximum brightness. Try doubling the resistor's value
if its too bright.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
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