Re: LED Questions (just two: )

chull13@xxxxxxxxx wrote:
Well - look Iike I sent my responce to the Author - Sorry!

So, brightness would be determined by the Current.

Yes.

Voltage just need to remaine within the operating range of the LEDs.

No. The supply voltage can be much higher than the operating
range of the LED, provided you keep the *current* within
the operating range of the LED. Look at this circuit:

+12V ---[470R]---+
|
[LED]
|
Gnd ------------+

If the LED Vf (forward voltage) spec is 2 volts, that means
that there will be ~2 volts across the LED when it is operated
in its current range. The 470 ohm resistor will limit the
current to ~ 21 mA. If the supply was 9 volts, you would
change the resistor to 330 ohms. If the supply was 100
volts, you would change the resistor to 4700 ohms. In each
case, the resistor limits the curret through the LED to about
21 mA.

Focus on controlling the current through the LED - the voltage
across it will automatically be correct, as long as you limit
the current properly.

Ed



Am I closer?

Thank you all for your help

.