Here's a little project I stumbled upon by accident.
Some time ago, I had a goal to learn a thing or two about the construction and repair of old 35mm manual focus lenses. I had an old lens that needed some work so I took it apart, lubricated it and got it back in working condition. It was admitedly more luck than skill, so I bought some broken lenses on eBay purely for disassembly practice. This LED Lamp is the result of the first broken lens I disassembled.
This particular Albinar 80-200mm zoom lens came apart easily, and when I was done playing with it, I had this idea of mounting some bright white LEDs inside the barrel of the lens and turning it into a funky lamp. The lamp would be a one-of-kind creation.
Regular white LEDs come in a variety of sizes and brightness. The ones I used were 3mm, rated at 14000 to 16000 mcd with a color temperature of 7000K. Each is wired to a series 100 ohm resistor. Twelve LEDs are mounted on a small round board. Four small alumninum spacers separate the board from the front glass element.
No attempt was made to make use of the original optics in the lens other than the front element. This piece of glass is there for the obvious reason - it keeps things from falling out. The rear of the lamp is where the lens mount used to be - I plugged that space with a black painted MDF plug.
To mount the lamp I ripped apart an old gooseneck lamp I had collecting dust. One end of the gooseneck screwed directly into the lens' metal housing. This also acts to prevent the lens from "zooming" and advertently coming apart. The other end of the gooseneck is screwed into a standard plastic housing from the electrical department of my local Lowes. I wanted an industrial look to the lamp and this housing was just right. It was also just large enough to house the transformer. The transformer itself is an old wall-wart from some long-lost device. In use, it's output is an unregulated 5V DC. I don't like keeping things plugged in continuously so I wanted the power switch to be on the primary side of the transformer; hence the box. The power switch came from Radio Shack. All electrical connections are heat shrinked and taped.
Both the LEDs and the transformer run very cool. Current draw on the secondary side is about 200 mA (5VDC) for all 12 LEDs. As can be seen in this picture, the lamp is wall mounted (two of the four screws are in studs; the other two have drywall anchors). It serves as a reading lamp for the top bunk.
The only downside to this lamp is that the all-metal construction of this old lens makes it rather heavy (and that's with only a fraction of its original metal and glass used). The gooseneck is not stiff enough to maintain all positions without losing to gravity. But my son likes it - it's something unique and it's his. Maybe I'll make another with some other spare parts...