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.

Is resistor necessary for LED?

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.

Which resistor do I need?

A rule of thumb is to find a resistor with twice the power rating. Here I would choose a 250 mW resistor since those are the most standard ones. Usually, you can just use the cheapest resistor you can find with the correct power rating.

Do I need a resistor for a 12v LED?

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, LEDs will only allow current to flow in the direction from the anode to the cathode.

Which leg of an LED is positive?

anode The longer leg is the positive side of the LED, called the “anode,” and the shorter leg is the negative side, called the “cathode.” Within an LED, current can only flow from the anode (positive side) to the cathode (negative side) and never in the opposite direction.

Which terminal must be at a lower voltage for an LED to turn on?

Knowing which side of an LED, or Light Emitting Diode, is the positive anode side and which side is the negative cathode side is essential if you want to make the LED emit light. For the LED to emit light, the voltage on the anode must be positive.

Should I put a resistor before or after the LED?

It doesnt 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.

Can high voltage damage LED lights?

LED lights are designed for a specific voltage, such as 12 volts or 24 volts. When LEDs are run at a higher voltage they become very hot. The heat can damage the LEDs, or the soldering around them, so they either start flickering, go dim or die entirely.

Which leg is longer on LED?

anode The longer leg is the positive side of the LED, called the “anode,” and the shorter leg is the negative side, called the “cathode.” Within an LED, current can only flow from the anode (positive side) to the cathode (negative side) and never in the opposite direction.