The difference between the power supply (battery) voltage and the LED’s forward voltage value. The important feature to note here is that the voltage value used in the calculation. The formula required is ohm’s law which states that the Resistance is equal to the voltage divided by the Current. Since automotive applications are one of the most popular uses for LEDs, I will go through an example of an LED lighting project that uses 12 volts as the power source. The procedure is to choose a resistor value that will produce the correct amount of current to flow in the LED-based on this forward voltage value and the value of the Power supply that is powering the circuit. Because of this variation, the value of resistor value will vary depending on what the LED color is. Typical Red, Green, Orange, and Yellow LEDs have a forward voltage of approximately 2.0 volts but White and Blue LEDs have a forward voltage value of 3.4 volts. The forward voltage value is the voltage required to cause the LED to light. This is because the color of the LED is determined by the materials used to make it and these various materials have different voltage characteristics. Since LEDs are available in various colors, the required resistance value will vary depending on the color of the LED. With this in mind, we will explore the requirements for the limiting resistor that must be used in an LED circuit. Since an LED is essentially a diode, it has a maximum current value that cannot be exceeded for any period of time. This is because an LED has a relatively low value of reverse polarity voltage that is allowed (normally about 5 volts). Failure to observe this polarity requirement could cause catastrophic damage to the LED. This means that an LED has a specific polarity that must be applied to make it produce light. LED is an acronym for Light Emitting Diode. So (12-3.4)/.050=172 ohms.Įxplain the idea of Calculating Resistor value for LED Lighting From the example above, if we use 5 white LEDs the current requirement is 10mA x 5 = 50mA. To use several LEDs in parallel, sum the current values.For a typical white LED that requires 10mA, powered by 12V the values are: (12-3.4)/.010=860 ohms.We’ll use the following formula to determine the resistor value: Resistor = (Battery Voltage – LED voltage) / desired LED current.Determine the voltage and current needed for your LED.Following these steps to calculate resistor value for LED Lighting by 12V, DC: Also, as the technology improves and production increases, the cost continues to be reduced. This is due to the excellent power efficiency and extended lifetimes of LEDs over incandescent lamps. LEDs are becoming more and more popular for a variety of lighting projects and needs.
#Standard resistor value table how to#
We hope reading How to Calculate Resistor Value for LED Lighting gives you what you would need for your project. Determining the resistor value for lighting LEDs is simple and straightforward, but we must take into consideration the color of the LED as well as the wattage rating of the required resistor, and the number of LEDs in the circuit.