Monday, July 1, 2013

12V Dual LED Adjustable Folding Table Lamp -- 5 watts

For us, reading in the evening is a major part of camping.  There are no distractions (which is probably another way of saying that there’s not much else to do at night, especially when it is cold or rainy).  Decent lighting is, of course, crucial.  We have been doing quite nicely with an overhead 110 V LED bulb, which is powered by our inverter – it puts out plenty of light.  The combination of the inverter and the bulb consumes about 12 watts, which isn’t a lot.  But especially when we are boondocking, every watt is significant.  Also, the overhead bulb is a little bit harsh.  Not bad, but not perfect.

So, in an effort to get better light with lower wattage, I wondered whether anyone had made a 12 volt LED table lamp for camping, and I was unable to find anything to fit the bill.  I have seen 12 V LED lanterns, but those are not reading lamps – the light goes out in all directions, and the “color temperature” of the LED bulbs tends to be toward the blue end of the spectrum.

We had previously installed LED “48 element” panel-type bulbs for our wall fixtures, which put out a nice warm light.  So I figured that I could make my own table lamp, using those bulbs.  Fortunately, when I remodeled the trailer, I removed an existing wedge-based dual fixture, and I was able to salvage the wedge sockets from that fixture.

In designing the table lamp fixture, I wanted something that folded into a compact shape and that was easy to adjust.  I also wanted to be able to project the light down (when we were reading at the table) and to adjust the light so that it would shine horizontally (when we were sitting with our legs up on the cushions).

So my design incorporates a lot of flexible joints, all of which rotate around quarter inch hex bolts that are tightened with wing nuts.  The tripod legs can be adjusted, the central joint can be adjusted, and the hoods holding the bulbs can be adjusted.  I made the whole thing out of oak, on the theory that it is sturdy, even when it is cut very thinly, unlike softwoods.

Anyway, here is an overview of the lamp – it’s about 14 inches high.  It looks kind of like a three-legged moose, which is part of the charm, I think:



And here is what it looks like when it’s turned on -- I have rotated the hoods or shades so that the LED panels can be seen:




To be honest, these photos make the lamp look somewhat better than it really is.  The finish on the wood is not perfect.  But I figured that I would wait and see how this thing works while camping, before I put in a lot of time in sanding and applying polyurethane.  I will say, however, that the lamp is nice and stable.  It does not wiggle at all.

Here is a side view of the lamp - the three legs are connected to a central piece, which is connected to a short riser.  The top assembly mounts on top of the riser:




And here is a shot of the side of the joints:





This is a close-up of the bottom joint:





Here is a detailed shot of the top joint:





In order to join the base unit to the top, I installed a threaded brass insert into the center of the top joint.  A hanger bolt comes up from the bottom and threads into the insert.

Finally, here is a picture of the lamp all folded up – the fork gives you some idea of the size of the lamp:


After I plugged the lamp into the 12 volt socket, I used the multimeter and found that this dual fixture uses 6 watts, saving us 5 watts (when compared to the existing 110 LED bulb plus the inverter).  That’s not quite a 50% savings, but it’s not bad.  We will see on our next camping trip whether the quality of the light given off by the table lamp is an improvement over the 110 LED bulb.  If not, I still had a lot of fun building the lamp, anyway.


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