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.
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.
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.
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.
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.
Fiber Optic Store Comment: We applaud Davis for his creative initiative in building a custom illuminator for his star panel! We’d like to point out that we also offer an ULTRA BRIGHT LED illuminator that would work perfectly for this type of project. It is powered by a 9 volt battery and could be easily built into the panel. CLICK HERE to go to our 1000M illuminator page.