Powering LEDs With AC

I am working on a couple of articles on installing LEDs in an AC (Alternating Current) environment, you know, the 120VAC we find in most domestic homes. The biggest push in the industry is to design LED lamps that work well in that market. The 12VDC market of the RVs is really small potatoes.

LEDs are intrinsically DC devices. They are diodes that want the current to flow in only one direction. To use them efficiently in an AC environment requires specialized circuits.

The problem all started with Thomas Edison. He wanted the electrical grid of the USA to be an AC grid and make use of the generators and such he had invented. Tesla wanted a DC grid, but he lost out. Now we have all our home filled with AC power, and the fixtures are designed to work in that environment.

The simple incandescent light bulb (a 60W for example) has an "Edison" base. This is a screw-in and the usual size is 27mm in diameter. The ground line is connected to the socket surrounding the base, and the power is applied to the contact at the bottom of the base. That electrical power supplies the full 120VAC current to the filament inside the bulb. The flow of current causes the filament to heat up to white hot and emit light.

The 60W incandescent bulb emits about 840 lumens of white light. This much light is required because all the light is coming from a single source, and it must be strong enough to fill a large room space.

In an RV the lights run on 12VDC. There are multiple light bulbs, each of which emits in the range of 150 to 250 lumens. Since these are placed throughout the ceiling and walls of the RV, there is no single source of light. Rather, the light is spread out and each source does not have to be so bright as with a 60W bulb.

We have had very good results if we use linear LED lighting in an RV. This spreads the source of the light even more, and makes for good indirect lighting.

So my forthcoming articles will discuss the pros and cons of using AC power for LED lamps. It can be done, but it tends to be more expensive. But it is very hard to convince people to look for a lighting method that does not use the old-style Edison-base bulbs they always have had.

Sam Penny, the Prudent RVer

Comments

[Norm Bauer]

Sounds like a great concept and w/ AC, realize savings on conductor and converter sizing. I'd be interested to find out how much RF would be produced AC vs fluctuating DC or an alternating bridge.

Also you might want to rewrite the above article( Tesla developed AC, Edison wanted 3-wire DC, and Westinghouse was the financier,had the political ear and the wear-with-all to build AC power plants).