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LED Protection Resistor Calculator

Example:

To calculate the value of resistor needed by the Super Bright LED below:

1, To begin, look at the LED's values for Vs, Vf and If in the red table below.
2, Transfer the values into the black calculator table
which is bottom right of this page.
3, Simply press the "Push to Calculate " button and the required resistor is calculated for you below.

Try the example
-Super Bright LED-
Battery Vs
(volts)
Vf
(volts)
If
(milliamps)
3mm red LED
12
2.1
30

 

L.E.D. Resistor Calculator
(using V(s) - V(f) = If x R)
                           
Enter your values in the text boxes
Your Supply Voltage
(Vs)
LED Voltage
(Vf)
LED Current
(If)
volts
volts
milliamps




Resistor required = Ohms

Please select nearest "preferred" value of resistor from the list (eg. If resistor = 135 then go up to 150):

22 - 27 - 33 - 47 - 56 - 68 - 100 - 120 - 150 - 180 - 220 - 270 - 330 - 390 - 470 - 560 - 680 - 820 - 1000