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4.5

Building the prototype

HAL consists of two parts: the cell and the inner part. Both parts are made from a white semi transparent plastic surface, which provides an interesting diffused effect when the LEDs, attached to the inner part, are lit. Although the initial intention was to modify the existing circuit, the fact that I had to work with 40 Digital pins forced me to rebuild the inner part of the lamp. I had to evenly distribute 36 LEDs in a 6x6 array. In other words, every LED would form a circuit that would be connected to the Wiring board, which would be programmed to connect and disconnect each LED circuit’s power. LED must have a resistor in series to limit the current to a safe value, if not they are destroyed almost instantly because too much current passes through and burns them out. In order for one to calculate the value of resistance he must refer to the Ohm’s Law. According to that law, Resistance = Voltage / Current. Finally the components used are 5volts 3mm Super Bright Red LEDs with 330 Ohms Resistors.

Fig. 49 Circuit diagram indicating how the first and the last LED is connected to the Wiring I/O Board. Having also the calculations for the appropriate resistors.

Physical Computing:

Using Everyday Objects as Communication tools

Fig. 48 HAL assembled and disassembled

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