MullOverThings

Useful tips for everyday

# Can I use an LED without a resistor?

## Can I use an LED without a resistor?

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.

## Do I need resistors with Arduino?

When building your Arduino projects, you use resistors to limit the amount of current going to certain components in the circuit, such as LEDs and integrated circuits. To calculate the resistance, you should use a modified version of Ohm’s Law.

## What wire do I need to connect LED with Arduino?

The next step is to start adding onto the hardware component of the Arduino. We will do this by adding a solderless breadboard to our setup, connecting up new parts with wire. USB Cable. Standard A-B cable is required.

## What resistor is needed for LEDs?

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 LEDs act as resistors?

LEDs do not have a linear relationship between current and voltage so they cannot be modeled as simply as a resistor using Ohm’s Law, V = IR . An LED can be approximated as a resistor with a fixed voltage source.

## Can I connect LED directly to Arduino?

Yes! Do what they do in LED lightbulbs for your home. Drive the LED with a current controller. Set the current controller to drive the current your LED is rated for.

## When should I 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.

## What type of wire does Arduino use?

A good source for wires is old computer and Telco cables. For breadboards, I recommend Telco #22 and #24 AWG wires, but prefer #24. Both stranded and solid #24 AWG is available in the Telco color…

## Do 12V LEDs need resistors?

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.

## Do I really need resistors when controlling LEDs with Arduino?

The short answer is, yes and no, it depends on your arduino and it depends on the color of your led. For instance, a 3.3V board does not require a resistor in series with a small green LED, because the forward voltage of the LED is pretty high, see this.

## What is the voltage of an Arduino led?

The voltage you know: Arduino runs at 5V. But not all that will go over the resistor. The LED also has a voltage drop, typically around 2V for a red LED. So there remains 3V for the resistor.

## What kind of resistor do I need for Arduino Uno?

The Arduino Uno uses the ATmega328 microcontroller. The datasheet says that the current for any I/O pin shouldn’t exceed 40mA, what’s commonly known as Absolute Maximum Ratings. Since you don’t have anything to limit the current there’s only the (low!) resistance of the output transistor.

## What kind of impedance does Arduino Uno have?

The arduino uno has a digital output impedance around 250 ohms. Long story short, if you drove an LED using PWM at 1.0V at a high frequency, for a typical LED, there is zero chance you will damage your digital output on an Arduino Uno. The PWM approach drives the LED in an open loop fashion (and so does using 1.7V power supply without PWM).