LED Lighting

A few years ago, the idea of replacing incandescent lights with compact florescents was "the answer". For most, it still is. But, LED lighting is starting to look like the next answer.

First, an LED is a light emitting diode. When the LED industry was young, your choice was red or red. The indicator lights on your computer, your car dashboard and a zillion other things are generally LEDs. Today, you can get them in red, yellow, green, blue, infrared, ultraviolet and, most important, white.

An LED is a solid-state device like a transistor. You run electric current through them and they emit light. Little heat is produced, they operate on about 3 volts per device and have an estimated life running 24/7 of 5 to 10 years and more. They are very energy efficient.

The problem was that each LED produced little light. The solution was to build a "bulb" using many LEDs. The one in the photo uses 12 LEDs, consumes a little over 1 watt but produces as much light as maybe a 25W incandescent bulb. While I have seen bulbs consisting of over 50LEDs, it becomes pretty clear that this approach doesn't scale well.

Well, the next generation of LEDs is here. A bulb built with a single one watt LED exists and prices are quickly dropping. The bulb in the photo cost $8. The same type of light using a single 1W LED is, today, about the same price and it will likely cost significantly less within a year, possibly sooner.

Bulbs (both the large number of small LEDs and small number of large LEDS) are available to run off 12V, 24V, 120V and 240V. In addition, there are bulbs that can run on variable voltages (for example, from 4 to 15V). The variable-voltage technology falls out of the need to make a 12V bulb that will perform well for from 11 to 15V. An LED is a "current device". That means that a small change in voltage will produce a large change in current making them easy to burn out with a small voltage change. The old approach was to put a current limiting resistor in series with the device. This helped but at the expense of wasted energy.

The solution is an electronic circuit that switches the voltage on and off such that the average current (and, thus, total power) is relatively constant. If you were adding the circuit to handle 11 to 15V, it is a trivial extension to make it work from 4 to 15V. The same holds true for, for example, a device that can operate from 100 to 250V.

Light Fixtures

When installing lighting, the cost of the fixture has always been more than the bulb itself. In many cases this is justified because the fixture has to deal with the heat generated by the bulb and allow bulb changes. Well, with extremely long life lights that generate virtually no heat, the whole approach can change. There are now complete fixtures being produced at reasonable prices that have from 1 to 16 watts of LED built in. With an expected life of tens of years (few lights are really on 24/7), non-removable bulbs make sense.

The above photo shows two different fixtures designed to snap in a hole in the ceiling. They are both from Insaini in Ontario, Canada. The little one, called an EcoPuck, uses a single one watt LED and costs $20. The other is called Lumique XE Downlight uses three 3 watt LEDS and costs $50. Both are designed to run on 12VDC.

While these are bright for LEDs, I was actually a bit disappointed. The EcoPuck would work fine for illuminating a hallway, for example but it sure isn't a "room light". The Lumique XE is pointable and designed to, for example, illuminate a painting or something in a display case. It will do that very well but, again, it isn't a "room light".

There are lots of other styles. I will soon have some samples of other types from China. Expect this page to evolve rapidly.

What About Retrofits?

If you have existing fixtures, there are some decent retrofit options. They include 120V standard screw base (there is both a flood bulb and a spot bulb in the photo, both 1W), 12V MR16 and even bulbs for autos. Each of the bulbs in the photo are old technology (lots of small LEDs). They cost between $3 and $9.

2010 Updates

While all the above information is still current, I have some new additions. I just received them (February 2010).

First, the 12V goose-neck light. In our house I purposely mounted three of the 12V sockets at about one meter off the floor. The idea was that a reading light could be plugged in there. But, I didn't have any pre-made unit so I have been using an auto license plate light bulb on my own adapter. Well, the commercial solution appeared and I bought three.

It is 250 cm goose-neck with a car lighter plug on one end and a light head on the other. The working side of the head has six surface-mount LEDs. The back side has an off/on switch. The plug has a built-in fuse and some metal fingers that you retract with push-buttons to keep it from rotating in the socket.

Current consumption is 78ma, making it about a 1 watt unit. More important, it is completely adequate for reading. It came from Ebest 24 for a cost of 5.19 pounds sterling.

The other units I purchased were for consideration as under-cabinet lights in the kitchen. I bought two types. The first is an LED unit with a festoon base—the typical base for an auto dome light. The unit I bought is an F31-2T from SuperBrightLeds at a cost of $4 each. They also sell the sockets if you need them for

The units draw about 35ma making the light about .4W. Not extremely bright but for under-counter use, I think they are adequate.

The more interesting of the two is a round unit about the size of for one cordoba coins. The face is aluminum with four surface-mount LEDs recessed in it. On the back are the circuit components for the driver and two pins to connect to 12 volts.

This unit consumes about 120ma making it a 1.4W unit. Bright and very compact design. It is also from UltraBrightLeds (part number G4B-CWHP4D for the cool white unit) and while more expensive ($12) is a very nice unit. You could recess it in the wood in the bottom of your cabinet and make it virtually invisible.