| The
Illuminator for The Star Panel |
| This project is to build a 3 LED light source
for the star field I built. I decided to use LEDs because of
their low power consumption, and very low (if any) heat dissipation.
They're expensive, but give a clean, light blue color to the
stars. Also, they're considerably smaller and brighter than
incandescent bulbs. The description below assumes that you have
some basic knowledge of current and resistance. |
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The Illuminator
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| LEDs: I went to the local
electronics store after finding nothing useful at Radio Shack
- the LEDs that they had were small (5mm diameter) and dim (3600
millicandella). For a punch in the gut of $10 each, I bought
three 10mm diameter, 7600 millicandella LEDs - perfect for the
job. The white LEDs are significantly more expensive than colored
ones. In the blurry picture to the right, from left to right
is the 10mm LED I am using, the RadioHack LED, and a smaller
LED from the electronics store. The green board is called a
breadboard - I had one lying around the house. |
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| Basic construction: I couldn't
build the illuminator until I knew where my fibers were. I found
them to be, as I had planned, about one inch apart. I laid the
LEDs out and began wiring as depicted in the circuit diagram
to the left. |
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| Circuit info: The LEDs I
bought were rated at 3.5V, 30mA max. The diagram to the left
gives, when R2 is set at 0 ohms, about 3v at 25mA per LED. I
don't want to fry the LEDs, though in the end, I had to settle
for a 7V power supply, which worked fine, giving about 3.2V
at 29mA per LED. In the picture, I had to put two 60 ohm resistors
in parallel because I ran out of 120s. |
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| Final summary: To hold all
of the parts in place, I dabbed a little bit of epoxy around
all of the leads and then soldered the components together.
I then soldered a 500ohm potentiometer in series with the light source
such that I can control the brightness of the whole panel from
one dial. LEDs are curious, and won't work at low voltages so
though a switch might be nice, its not necessary. |
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