How to Wire LEDs

Use LEDs in your next science project.

You can wire your own LEDs for a project. LEDs, also known as light emitting diodes, can be very useful because of the amount of light emitted with only very little power use and very little heat dissipated. They can be easily added to any project, but they have distinctive characteristics that set them apart from incandescent bulbs when it comes to safe, effective wiring. Plan and wire your LEDs carefully to avoid destroying them and to help with future maintenance.

Things You'll Need

• 14 to 16 gauge wire
• LEDs
• Disconnectors

Instructions

1. Plan your wiring for the future. Even though the life an LED is longer than that of an incandescent light bulb, it still has a finite lifespan. Because LEDs have two lead wires and do not have a base that they can plugged or screwed into, you will need to plan accordingly. Never solder the LEDs directly to your project unless you only need it to work for a short time.

   Get some disconnectors. Some disconnectors can be crimped to connect to the lead wires on the LEDs. The longer lead on the LED is the positive side. Crimp one disconnector to the LED and another to a wire to connect to the power source.

2. Provide enough power to maximize the amount of light the LEDs give off. LEDs will light up when underpowered, but it is better practice to provide adequate power.

   Look for the specifications on the LEDs you have purchased or are considering purchasing. Find the diode forward voltage requirement for the LEDs. This is the voltage you will need to provide for each LED in a series configuration. The following list contains the typical diode forward voltage requirements for different color LEDs if you cannot find the manufacturer's specifications.

   Blue (430 nm) 4.6 V
   True Green, Blue, White 3.3 V
   Green 2.2 V
   Yellow 2.1 V
   Red or Orange 2.0

   Calculate how much power you will need according to this list or manufacturer's specifications. For example, if you want to wire 3 red LEDs in your project then (3 x 2V = 6V) you will need to provide 6 volts of power (4 AA or AAA batteries will work).

3. Provide a resistor to protect the LEDs. The resistor will reduce the current so the LEDs are not destroyed. Calculate the LED resistor value with the following formula:

   LED Resistor Value, R=(supply voltage - LED voltage) x LED current

   When using a 6V power source such as 4 AA batteries, the supply voltage equals 6V. The LED voltage for red LEDs is 2V. Use the LED current provided in the manufacturer's specifications. If the current is not provided, use 20 mA. Using these values in the formula, yields (6V-2V) x 20mA, or 80 ohms minimum resistance. A 100 ohm resistor will work fine.

4. Use heat-shrink wrap or electrical tape around any connections or exposed metal in your wiring. This will help avoid a short circuit that may cause your LEDs to be destroyed.

5. Continue to add additional LEDs in series and wire and connect each that same way as described. The LEDs should be connected positive to negative. You can change the number of LEDs or the color but you will need to calculate the required power and resistor needed.

Tips & Warnings

• Finish your circuit completely before applying the power source. Put in the batteries or plug into the wall (if using an AC to DC converter or power brick) last.

References

• LED Center
• Science Buddies: Electronics Primer: Use a Breadboard to Build and Test a Simple Circuit