Friday, April 10, 2009

led motion sensors that fade in and out

As I have previously expressed, I have wished for motion sensor lights that fade in and fade out (so they aren't as jarring). I think this way people would be more willing to embrace motion sensors, and thus not leave lights on in a room that the might come back to shortly.

Make magazine has a question from "Shawin" on their website on how to make one of these yourself. He asks:
"We are renovating an old house we just bought and I wanted to have the rooms fitted with motion-sensors so that lights automatically turn on when someone walks in, and off when the room is empty. The problem is that I want the lights to fade-in/out instead of suddenly turning on/off.
Can someone please tell me how to do that? Are there existing switches that I could use?"
There are some suggested approaches on how to do this but no existing products mentioned.

For those of the less diy electronics set I found some ledon the web:

Philips Stumblelight:
"Upon detecting motion at night, StumbleLight instantly provides light at full intensity for 12 seconds and, if no motion is detected after 12 seconds, will slowly fade from full intensity to off."
Philips press release

"Light fades out gently when no motion is detected
No wiring required (requires 4C sized batteries)
Minimal battery consumption provides up to 6 months use
Only works at night due to a built in a photo sensor"

Most of the motion sensor lights I found have a limited motion sensor range. Some add infrared detection to the motion to reduce false activations. Many turn off after thirty seconds (not really long enough in my book as there are too many things for people to stand behind in a house for 30 seconds)

Some have a photo cell so they don't waste energy turning on when it's light out.

This one glows dimly then turns on full bright when it senses motion

So does the 2nd one and it also has a photo cell

Stairs product from smart home depected at top

Many of the ones I have bought suffer from being too dim and a lot of the reviews agree.

One note for those making their own with motion sensor switches, using LEDs will give you a much nicer experience than fluorescents because they don't have the pause and flicker on turn on. LEDs are being used for brake lights because they turn on so fast (of course I'm asking for gradual turn on which doesn't require fast, but if there is a pause before it starts to do anything people think the motion sensor isn't working and get annoyed)

On amazon I found a motion sensor LED light that advertised:
"the sudden activation startles unwanted visitors but also provides safe entrance and room lighting for your family and guests."
Am I barking up the wrong tree here?

Thursday, April 9, 2009

chinese researchers improve white LEDs

The article claims they are making them cheaper but doesn't really discuss it much other than mentioning using plastic like materials. They do state they have made them put out 50% more light (so I guess you can claim you'd need fewer LEDs per bulb and thus cheaper, though it seems a lot of the cost is in the power control circuitry)

Also of quantitative energy measurement interest, they state below that 20% of electricity is used for lighting, They also quote the DOE saying LEDs could save 30% of energy consumption.


Maybe I'm not getting it, but it seems to me if you assume that LEDs use 0 energy, and replace all lights, if you believe the first number that would only reduce our energy consumption by 20%.
clipped from
Chinese researchers have LED manufacturing breakthrough that could lead to new white LEDs for indoor use

It's believed about 20 percent of all electricity used across the world is currently used to light homes, businesses and other buildings.  For households and buildings still using incandescent bulbs, it's possible 95 percent of the energy flowing through them is being wasted.  
Furthermore, the US Department of Energy previously said LEDs could help reduce the country's national energy consumption by 30 percent by 2025.  If true, that will help households in the U.S. save $125 billion total in power bills per year.
Chinese researchers are working on a new LED that consists of cheap, inexpensive plastic-like organic materials that could help boost efficiency.  The new "tandem" structure allows it to produce up to 50 percent more light as LEDs used today, including white light that is necessary in homes and businesses.
 blog it

Wednesday, April 8, 2009

CFL power factor hidden energy cost

Slashdot has a post commenting that due to the power factor of the CFL bulbs utilties are having to use a lot more resources than you think to power the bulb. LEDs have a near perfect power factor according to this article which jives with my very limited memory of EE. Still though you are still using less resources with CFL (and consumers are paying a lot less in the short term until utiltiies figure this out and/or the costs to replace those used resources and clean up after them come to bear)
"We've seen compact fluorescent lamps start to take over shelf space at the local hardware store. Replacing a 60 watt incandescent with a 13 watt CFL seems like a great savings, though many consumers are disappointed with the slow warm-up times, lower-than-advertised lifetimes, and hassles of disposing the mercury-containing bulbs. Now EDN reports they may use more energy than claimed due to their poor power factor. Mike Grather, of Lumenaire Testing Laboratory, 'checked the power factor for the CFLs and found they ranged from .45 to .50. Their "real" load was about twice that implied by their wattage.' The good news: you're only billed for the 13 watts of real power used. The bad news: the utilities have to generate the equivalent of 28 watts (that is, 28 VA of apparent power for you EEs out there) to light that bulb. Until they fix these issues, I'll hold on to my incandescents and carbon arc lamps, thanks."
 blog it

Friday, April 3, 2009

LED bulb screw in replacement for incandescent

Techbargains has cheap LED screw in bulbs that use 2 watts of power, a significant power savings over incadescent and CFL, though I'm not sure how bright they are. But if you have light socket that you need just a little bit of light from, these would be a good bet. Keep in mind the color temp will be less yellow (aka more blue)

2 Pack 18 LED 2-Watt Spotlight Light Bulb $9.99 Free Ship,
Apr. 1 7 AM

Meritline has the 2 Pack 18 LED 2-Watt Spotlight Light Bulb for a low $9.99. Free Shipping. Tax in CA, MA.

 blog it

eco heater on sale at amazon today

I haven't personally used one nor have I read detailed reviews. The Amazon reviews say it uses 400 watts, compared to 750-1500 standard space heaters. Of course, the electricity consumed is basically all turned to heat in all space heaters, but the question is how efficiently they raise the temperature you feel in the room. That's why you see ones with dishes behind them to focus the heat. Supposedly this heater does a better job at this. Apparently it's also unobtrusive and can be painted over, which is good for "aestheticmetric"

It's on Amazon's friday sale (today only -- I'm not sure how much of a discount relative to normal days)