Innovative, eye catching rainbow 3mm LED that contains an inbuilt IC that causes the LED to cycle through the red, green and blue elements, individually and then in combination. Colour cycles every 33 seconds. Diffused lens type.
Q. Do you need to use a resistor with these leds ?
A. Thanks for your enqury. For all LEDs the Vf figure is the important voltage, a resistor is only required if the supply voltage exceeds this in order to “lose” the excess voltage. To calculate a resistor value use the formula
R (resistor) = Vs (supply)-Vf (led) divided by the current required (usually approx 80% of Imax) in this case use 20mA. The resistor power rating will depend on the amount of energy it is required to disperse, the higher the voltage the higher the power value – Voltage (across resistor) X Current.
