Friday, October 09, 2015
LED Torchiere Conversion
Twenty-three years ago, my wife and I moved into an apartment with very little built-in lighting, and purchased a couple of torchiere floor lamps to put in the living room and office. Their 300 watt quartz-halogen lamps provided a powerful, white light when turned up, and could be dimmed to a warm glow for quieter evening settings.
Twenty years ago, we moved into the house we now own, and placed the two torchieres in the living room, making for nice, soft indirect lighting on either side of our two chairs.
Perhaps 15 years ago, we picked up a couple of wall-mounted Quartz-halogen projector lamps in the "as-is" section of the Burbank IKEA. I mounted these as reading lights on the shaft of the torchieres (one for each of us), removing the torchieres' failing internal dimmers and routing the reading lights' wires through the now-available dimmer control opening and down through the core of the torchieres' poles to their DC power "bricks." I added external, remote-controlled AC dimmers for the torchieres.
Some years after that, I mounted rear satellite speakers for a surround-sound audio system high on the poles of each of the torchieres flanking our seats, firing rearward and slightly inward to reflect off the wall behind. The speaker wires joined the AC wires feeding the torchiere lamps, and DC wires powering the reading lights.
I've been slowly converting our home lighting from incandescent to LED (and very thankful never to have been faced with the ugly colors of fluorescent lighting). I'd noodled solutions for replacing the two 300 watt torchiere bulbs with lower-power LEDs for more than a year, researching available LEDs and power supplies (I still wanted dimmable lighting, which is a bit more exotic for LED driving circuits). Of late, there have been an increasing number of BIG, postage stamp-sized LEDs which produce light output adequate to replace any household application. I'd almost committed to buying separate components and fabricating a heat-sink/cooling system, when I stopped to look more closely at a LED ceiling down-light conversion kit at Costco. After some thought, I bought the $27 kit, containing two fixtures promising "same output as 120 watt" incandescent reflector flood lights, and 1,250 lumens of light output from only 21.5 watts. Manufacturer quotes of output of the 300 watt Quartz lamps in our torchieres quote nearly 5,000 lumen output, however, that's omnidirectional - light radiates in all directions from the glowing filament. LEDs output most of their light perpendicular to a plane, which is exactly where I want the light going - up into the ceiling. So I thought I might get away with a lower rating to achieve similar light levels.
Once home, I removed the diffusing lens (just breaking it off, then discovering that I missed two screws to remove it reversibly, which turned out to be moot) screwed the medium-base bulb adapter (the familiar threaded light bulb mount for the U. S.) into a work light socket and fired one of the fixtures into the ceiling at the same height as the torchiere lamps. It wasn't bad - about the same output as one of our torchieres which has an old, darkened lamp which was probably putting out half as much light as it could. But it was disappointing next to a freshly-relamped instrument.
I considered just going with the reduced light level, but then decided that I might be able to Siamese the two LED fixtures by sawing about 1/4 of each of their housings off. They would both then fit (sort of) within the upturned shade of the torchiere after I surgically removed all the original socket and reflector parts.
Further exploration and experimentation revealed that I could free the array of 18 LEDs and the steel disk to which they are bonded - I realized it wasn't glued as I first suspected, but merely stuck by silicone heat sink grease. The hockey puck-sized dimmable power supply was easily separated, though I had only about 1/3" of wire with which to solder on four connections between the power supplies and LEDs.
A couple of hours wandering around Home Depot yielded some galvanized steel plates (made for joining construction lumber), pop rivets, some threaded rod and a Plan.
I riveted the LED arrays from both of the fixtures on my fabricated mounting plates/heat sinks (with yet more heat sink grease), and tucked the power supplies underneath. The whole assembly floats above the torchieres' shallow, upturned bowl-shaped shades on two threaded rods.
Before (dimmed very low for photo)
After (also dimmed low)
When I fired it up, I was thrilled to find that the combined output of the 43 watts of LEDs equals or exceeds that of the brand new 300 watt quartz-halogen bulb, and the pattern on the ceiling and walls is perfect. The lights dim as hoped, though there is little to no color change (having warm colored lighting at night may be a better idea to prevent unwanted wakefulness), and the light levels abruptly change at some points - which matters not. Power consumption will drop to 1/7th of the original, and in the summer, the air conditioner will have to contend with over 500 fewer watts of heat in the living room at night.
The original halogen light on the left, and the LED on the right - the dimmers are set at only about 30 per cent, but the LED exhibits none of the reddish color change of a filament bulb.
Success! Our 20th-Century lamps are now 21st, and will continue to serve as reading lights and Surround Sound satellites for years to come.