P11543: Variable LED Hemispherical Imager
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LED Cluster Concepts

Table of Contents

LED Cluster Concepts

7 LED Cluster

This concept incorporates 7 LEDs in a cluster, with a single white center LED surrounded by a circle of 6 color LEDs. This basic structure can be seen in the included picture.

LED Cluster Concept

LED Cluster Concept

Concept Prototype

To further evaluate this concept a prototype model was constructed. The cluster was made to represent the ring shape of the 7 LEDs. This model was only created in order to develop a general idea of the LED light dispersion, and does not represent any method of controlling the luminous intensity of each LED.

Prototype Construction

The prototype was designed to run off a 6V battery pack which uses 4 AAs. The current to each LED is limited by a resistor in series, and all 7 LEDs are in parallel with the voltage source.

To create this prototype, components available on hand were used. Due to this, the resistance values and properties of the LEDs were not as precise as desired. A cyan LED was not available, so a second blue LED was used in it's place. Five of the LEDs were in the desired T 1-3/4 size, but the orange and one blue LEDs are in a different package. The LEDs also have wider cone angles than desired.

Resistance values were selected to limit the current to our expected maximum level. The current driving the white and two blue LEDs was calculated as 25mA through 100 Ohm resistors, and the current driving the red, yellow, orange, and green LEDs was calculated as 26mA through 150 Ohm resistors. At this time, it is expected that our final concept will have a lower maximum current.

Images of the completed prototype can be found below:

Prototype LED Cluster ON

Prototype LED Cluster ON

Prototype LED Cluster OFF

Prototype LED Cluster OFF