Current Limiting Resistor. Also keep in mind these two concepts when referring to the circuit above. Using limit current resistor 1.
Additionally resistors behave oppositely from leds in relation to its temperature as temperature increases resistance also increases. Using the circuit above you will need to know three values in order to determine the current limiting resistor value. This equation and calculator helps determine the value of the resistor to add to a light emitting diode led so that it can limit the current moving through the led.
A few milliamps of current is enough to make an led glow.
Additionally resistors behave oppositely from leds in relation to its temperature as temperature increases resistance also increases. The vf forward voltage of white leds is about 3 1 to 3 6 volts so four in series would require a voltage supply of 12 4 to 14 4 volts to turn on somewhat. It should have a resistor or a way of limiting the current. Using the desired operating characteristics and led specs solve the appropriate equations for the ideal resistor values.
