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How to Make an LED Light Array

LEDs are semiconductors created for the purposes of illumination. They may be connected to form an array by placing them together in series, parallel or both. When connected in series, LEDs share the same voltage, but have different individual currents. This occurs when all of the LEDs share the same resistor. When connected in parallel, LEDs share the same current, but have different voltages. This occurs when each LED has its own resistor. To make an LED light array, first decide whether the components will be connected in series or parallel, and then calculate the size of the resistor needed for each LED. This size may be found with the use of Ohm's Law. It is easiest to begin by first practicing with a series circuit.

Things You'll Need

3 green LEDs
270-ohm resistor
1k-ohm resistor
Solderless breadboard
9-volt battery
Battery holder
Jumper wires

Instructions

- 1
  Study Ohm's Law to find the value the resistor R should be for one LED. The formula is R = (Voltage Source -- LED Voltage) / LED current.
- 2
  Examine the specifications for one low voltage green LED. These may be found on the package or the manufacturer's website. A small LED has a 2.2 voltage, and can have a maximum of only 10 milliamps.
- 3
  Apply Ohm's Law to a series circuit of three green LEDs. The solution is R = (9 V -- (2.2 V + 2.2 V + 2.2 V) / 0.010 A = 240 ohms. Since 270 ohms is the nearest greatest resistor value that is standard, use this one. Notice that this resistance is the minimum value that can be used, and so a higher one may be substituted.
- 4
  Add the battery holder to the breadboard. Connect the first green LED so that its positive or plus side is attached to the red lead of the battery holder. The LED's plus side is the longer leg.
- 5
  Attach the plus side of a second green LED to the minus side of the first one. To avoid having the LEDs too close together, jumper wires may be used. Follow the same procedure to attach the remaining green LED, where its plus side is connected to the minus side of the second. The LEDs now form an array.
- 6
  Connect the minus side of the third LED to the black lead of the battery holder. When the battery is added, the array will light up.
- 7
  Experiment by substituting a 1k-ohm resistor in place of the 270-ohm resistor. Observe that the array is not as brightly lit as before.

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