I bought a Philips 5.5W LED MR16 spot light (.PDF) for about $20.00. It puts out 300 lumens of warm white light. The light needs 12VAC, and the base has two pins spaced about 0.3 inches apart, which fit perfectly into a screw terminal. I’m using it above my workbench for illuminating the circuit boards or whatever I’m working on. I used a 9VDC unregulated wall wart adapter for power, and soldered a green terminal strip onto a short length of wire, with a 5.5 by 2.5 mm power jack to accommodate the wall wart’s plug.
The light’s body is made from metal and it does get rather warm, but nowhere as hot as a halogen bulb. I like the bright beam of light, very little goes to the side because of the reflector around the four LEDs. The adapter says its output is 9VDC; the meters measure 8V, but the LEDs are very bright. The light’s package says the light is dimmable.
I’m thinking that these 5.5W spot lights would make a good replacement for some other task lights I have. Problem is they have to have an adapter or transformer to get down to 12V. I need to find out how much power is wasted in the adapter or transformer. I would not want to replace an 8 watt light with a 5.5 watt light if the adapter or transformer wasted 3 watts, so that the 5.5 watts plus 3 watts add up to 8.5 watts or a half watt more than the 8 watt light. There may be other factors, too. For instance any additional devices used to control the light, such as a dimmer or wireless switch, which would add to the wasted power.
I’ve been getting most of my LED light bulbs from Home Depot (I’ve bought four Philips L Prize LED lights, total $100). I think they have their own less expensive brand name EcoSmart. When I look at the shelves, the lights I see left are all daylight white. Seems that they are perpetually out of stock on the warm white Ecosmart LED lights. No matter, though. The Philips lights are more expensive but more than pay for themselves over time in electricity savings. The Philips L Prize lights are $25 but save much more than that over a decade or so. I checked the ‘net and the cheapest I could find them was $33, so I think I should have bought more when they were on sale.
One important point that people fail to recognize. The L Prize lights are dimmable. When you dim a regular incandescent light, the light gets very amber, until it’s more reddish than one would like. This does not happen to a LED light; the light stays the same color, and the lamp dims to a lower light output. We get the best of both worlds: lower light output and light that’s the right color. And we save a lot of money while we’re doing it.
“how much power is wasted in the adapter or transformer”
Typically ,for an 10W/9V adapter about 2-4W are wasted on idle => this decrease total efficency .The only solution is an S.M.P.S. Some phone chargers or other small adapter chargers do much better .1 -1W of power wasted when idle . The laptop chargers are a little better then regular transformers ( UC384x controller ) .
I put my hand on the older unregulated adapters that have a transformer, and I can feel that they are warm, and that’s wasted power. The newer switching type adapters seem to be a lot cooler and waste less power. This may be because the EPA has the “Energy Star” thing where they try to get the electronics makers to ‘go green’ and reduce power waste. I think that the older transformers could have been more efficient if they had wanted them to be, but it would have cost more so they chose the cheap route. Thanks for the comment and info.