Posted - 01/19/2004 : 4:30:55 PM
| Moderator's Note: The following how-to was originally posted by Dave Grassing in the Railroad Camp Construction thread.
As promised a few weeks ago here are the details of the construction of a LED Street or yard lamp.
Materials required: 1 1/2mm brass or copper tube plus 3mm brass or copper tube. This last should just slide over the 1 1/2mm tube. Next a 3mm white LED, a small piece of card or similar to make the shade, thin insulated wire, both red and black (just thick enough to feed through the smaller tube) 1 1K resistor, solder and soldering flux, Epoxy resin and paint.
First cut a length of the small tubing about 3 1/2 inches long then a short length of 3mm tube approximately 1 1/2 long. This will be the base of the lamp. Take a length of black wire, strip about ¼ inch of the insulation and solder to the inside of the larger tube. Next slide the smaller tube down through the larger one, adjust to your required height and carefully solder the tubes together. Do not apply too much heat so as not to unsolder the black wire.
Take a length of red wire, strip about a 1/2inch of the insulation off of one end and solder, to make the conductor stiff. Feed the red wire down the lamp tubes and epoxy in place, making sure that the conductor is not touching the tube.
At this stage check with meter that there is no short.
Take a small circular piece of card or plastic, the size you want your lamp shade to be and drill two small holes 2.3mm apart. These should allow the prongs of the LED to just pass through then dish it slightly so that it looks like a lamp shade, You can use either a standard 3mm LED or a ultra bright one. Pass the prongs through the holes and epoxy the shade in position on the LED. See photo. When set, bend the prongs as per the photo, the longest one being soldered to the conductor sticking out of the top of lamp post, the other being soldered to the side of the lamp post itself. Should you require the lamp to extend further out from the post just extend the LED probes using some very small tube. DO MAKE SURE THAT THE LONGEST PROBE IS CONNECTED TO THE CONDUCTOR THAT COMES UP THE INSIDE OF THE LAMP POST WHICH IS, OF COURSE, THE RED WIRE.
After your lamp post is finished connect a 1k resistor to the red feed wire and then to the positive of a 12 volt supply and the black to the negative. It should now work.
A 5mm LED can be used instead of the 3mm one.
FINAL MODERATOR'S NOTE: For those who would like to see the results of Dave's lighting work, here is a link to two excellent nighttime photos of his and Midge's "Railroad Camp" diorama