Sunday, 20 January 2013

LED Cube 2x2

Logging 1st milestone in the LED Cube project.

The design of the 2x2 LED cube is fairly simple as each layer only consists of 4 LEDs.
Each LED has a positive terminal (anode) and a negative terminal (cathode). There are two methods to determine the LED's terminal.
Figure 1. Largest piece among the 2 conductors is the cathode.6

From the figure,
1. Anode is +, cathode is -
2. Observe flat surface at cathode compared to anode.
SuperBright Blue LED wavelength: 470nm
Forward voltage: 3.4v
Max forward current: 30mA
View angle: 0 to ~15 degrees.
Intensity : 4000mcd (max)

Resistance: 100 ohm , 1/8 watt (0.25 watt)
Theoretical max forward current : (5v output - 3.4) / 100 = 16mA

Actual current draw: 8.5mA (max due to pulse)
Actual voltage output: 4.8v
Actual voltage across LED:  ~3.4v
Actual power dissipated by resistor = (8.5m)^2 * 100 = 0.007A

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