## How do I know what resistor to use with LED?

We’ll use the following formula to determine the resistor value: Resistor = (Battery Voltage – LED voltage) / desired LED current. For a typical white LED that requires 10mA, powered by 12V the values are: (12-3.4)/. 010=860 ohms. To use several LEDs in parallel, sum the current values.

Can LEDs share resistors?

Often multiple LEDs are connected to a single voltage source with a series connection. In this way multiple resistors can share the same current. Because the current through all LEDs in series is equal, they should be of the same type.

### Do resistors go on positive or negative side of LED?

Since this resistor is only being used to limit current through the circuit, it can actually be located on either side of the LED. Placing the resistor on the positive (anode) side of the resistor will have no differing effects from placing the resistor on the negative (cathode) side of the LED.

Do resistors make LEDs brighter?

The LED uses the power to make light (more power, more light). The resistor does not make light, it makes heat (more power, more heat). If you need to make an LED brighter, adding batteries is wasteful: you’re better off using a smaller resistor!

## Why do you need a 330 ohm resistor for an LED?

Detail: 330 ohms may be used by some people as a “get you going” value that works “well enough” in many cases. The purpose of the resistor is to “drop” voltage that is not required to operate the LED, when the LED is operating at the desired current.

How big of a resistor do I need for a LED?

LEDs typically require 10 to 20mA, the datasheet for the LED will detail this along with the forward voltage drop. For example an ultra bright blue LED with a 9V battery has a forward voltage of 3.2V and typical current of 20mA. So the resistor needs to be 290 ohms or as close as is available.

### Do you need a resistor for every LED in parallel?

No you don’t, if an LED requires 3V of power and you have a source that provides 3V of power then resistor is not necessary. If an LED requires 12V of power and you have a car battery — you can connect it directly and power it that way.

Which way do I wire my LED?

Determining LED Polarity: The cathode should be connected towards the ground or negative side of the driving voltage source, and the anode toward the positive side. LEDs usually have their cathode marked in some manner.

## How do you control the brightness of LED lights?

To change the brightness by adjusting the resistor value – just add a potentiometer in series with the LED. When you adjust the knob of the resistor, the brightness of the LED will change. Another method is to turn the LED on and off fast.

Why does the resistor value vary with the color of led?

Because of this variation, the value of resistor value will vary depending on what the LED color is. 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.

### How do you pick the right resistor for LED lights?

Basics: Picking Resistors for LEDs. (Power supply voltage – LED voltage) / current (in amps) = desired resistor value (in ohms) We end up with a resistor value of 48 Ω. And, that’s a fine starting resistor value for use with a yellow LED and a 3 V source. Let’s look at resistor values for a moment.

What is an LED (light emitting diode)?

An LED (Light Emitting Diode) emits light when an electric current passes through it. The simplest circuit to power an LED is a voltage source with a resistor and an LED in series. Such a resistor is often called a ballast resistor. The ballast resistor is used to limit the current through the LED and to prevent that it burns.

## What is the simplest way to power an led?

The simplest circuit to power an LED is a voltage source with a resistor and an LED in series. Such a resistor is often called a ballast resistor. The ballast resistor is used to limit the current through the LED and to prevent excess current that can burn out the LED.