# Your question: Do you need a resistor for LED lights?

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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. … If the voltage source is equal to the voltage drop of the LED, no resistor is required.

## Do 12 volt LED lights need a resistor?

LEDs can be ran off multiple voltages, but a series resistor is required to limit the current in the circuit. Too much current in an LED will destroy the device. As with all diodes, LED’s will only allow current to flow in the direction from the anode to the cathode.

## Why do you need to use a resistor in series with a LED?

The slightest difference in LED or supply voltage may cause the LED to light very dim, very bright, or even destroy. A series resistor will ensure that slight differences in voltage have only a minor effect on the LED’s current, provided that the voltage drop across the resistor is large enough.

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## What size resistor do I need for 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 I need a resistor for a 3V LED?

Many 3V LEDs are not exactly 3V, they may range a bit like 3.0-3.2V. The idea of a resistor is to limit current. Even if you match a LED exactly to a voltage, it may draw more than the LED current rating. The resistor is just a safety feature to save the battery (and LED) from a short circuit current overload.

## When should you use a resistor?

The main function of resistors in a circuit is to control the flow of current to other components. Take an LED (light) for example. If too much current flows through an LED it is destroyed. So a resistor is used to limit the current.

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

Determine the voltage and current needed for your 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.

## What happens if you don’t use a resistor with an LED?

When hooking up an LED, you are always supposed to use a current-limiting resistor to protect the LED from the full voltage. If you hook the LED up directly to the 5 volts without a resistor, the LED will be over-driven, it will be very bright for a while, and then it will burn out.

## Why don t LEDs have built in resistors?

The resistor doesn’t lower the voltage to the LEDs, it’s resistance limits the current. If, by “lamp”, you’re referring to an incandescent lamp, they’re designed so that with the rated voltage across them their resistance will limit the current through the lamp.

## Do you put the resistor before or after the LED?

It doesn’t matter! The resistor can go before – or after – the LED, and it will still protect it. the current that flows out of a battery is always equal to the current that flows back into the battery.

## Will a resistor dim an LED?

Can led lights be dimmed using resistors? Dimming an LED light is as easy as adding resistors to the connection or even several resistors, to ensure you get the right brightness – this is called analog dimming. … Once you’ve got your resistor values all worked out, the rest should be a cake walk!

## Do resistors go on positive or negative?

If you think of the wire as being a pipe electricity flows through, you can think of a resistor as being a narrow part of that pipe, that chokes off the flow. Resistors don’t have positive and negative sides — you can hook them up in either direction and they work just the same.

## How many volts is a green LED?

The forward voltage rating of your Green LEDs depends on the silicon elements and dopants used, but is likely somewhere from 2.2 to 3.3 V when conducting.

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