This post is really a part of my continuing build log article on the Repair Shop, but I thought it might be of general interest. This is how I install lighting by making my own LED fixtures. The interior of the repair bay is illuminated with fifteen light fixtures, arranged in five rows of three fixtures. Each row is directly under one of the main roof trusses.
I started casting the fixture shades in acrylic resin using a silicone rubber mold last night. I will post more photos when the shades are completed. If you do not want to cast your own fixtures, a suitable substitution would be the metal casting from an Ozark Miniatures drop light kit, OM P/N 264. Each fixture will hold a single 3mm warm white 60-degree viewing angle LED. The LEDs are available from The LED Light Company, http://www.theledlight.com/, item number LED3-60DG-WWY-6.
I made the receptacles from a single 30-pin IC strip socket by cutting the socket into fifteen pieces with two pins on each piece. The strip socket is available from Jameco Electronics, http://www.jameco.com/, P/N 104054.
I bent the pins on each receptacle at a 90 degree angle away from each other. I cut pieces of 3/64” diameter brass tubing to connect the receptacles. The brass tubing has an inside diameter of 0.035 inches which makes for a nice tight fit with the 0.025” square pins on the receptacles. The 3/64” outside diameter accurately represents 1” diameter metal conduit in 1:20.3 scale. I placed miniature brass eye pins on each section of brass tubing before inserting the receptacle pins into the tubing. The eye pins are available from Micro-Mark, http://www.micromark.com/, item number 60405. The loops of the eye pins are 3/64” inside diameter so they fit tightly over the brass tubing. I clipped off the pointed end of the eye pins about ¼” above the loop. Here are the parts needed for each truss.
I flowed a small amount of solder into the ends of the brass tubes where the receptacle pins were inserted to guarantee good electrical contact between the pins and the tubing. I soldered a 2” length of brass wire into the left end of the tubing. I soldered one lead of a 120 ohm, ¼ W resistor into the right end of the tubing. I drilled small holes in the underside of the truss for the eye pins and attached assembled section to the truss. I painted the plastic portion of the receptacles and the soldered brass leads with flat black acrylic paint. Here is how the assembled conduit and receptacles fit on the undersides of the trusses.
Here is a close-up of one of the receptacles.
When the trusses are added to the structure, I will solder the end of the brass wire connected to the left ends of the tubing to the +12 volt lighting bus which runs along the top of the large center support beam. I will solder the end of the resistor connected to the right end of the tubing to the ground bus which runs along the top of the right wall.
The fifteen LEDs will be wired in a 3 x 5 series/parallel array. Each 120 ohm resistor dissipates 48 mW. Together, all resistors dissipate 240 mW. Together, the 15 LEDs dissipate 960 mW. Total power dissipated by the array is 1200 mW. The array draws 100 mA of current from the +12 volt lighting power bus.
This lighting arrangement provides excellent illumination for the interior of the repair bay. The warm color enhances the wood surfaces and brings out the interior detail. The 60 degree dispersion angle spreads the light evenly. The “plug-in” fixtures allow for convenient replacement if a LED ever burns out. The 100 mA current draw is extremely low for the amount of light produced. The required parts were readily available, easy to assemble, and relatively inexpensive.
Bob
