LED lighting ?

\On a sunny day (Fri, 05 Apr 2013 08:05:10 +0100) it happened Charlie+ wrote in :

I^2.R losses. need very thick wiring, length can be hundreds of meters in total. Local converters may be better. Chemical reactions at DC ? corrosion? Switch problems: DC switch contacts need more distance to stop the arc.. but could be made solid state..

So that is why I have 12 V cable to my LED RGB strips :-) And one converter... :-)

What makes you think that computers will have 400+ W power supplies in the far future?

be

d .

better yet, get rid of wiring entirely and go for Wireless Power Transer (WPT) Imagine being able to place your luminaires ANYWHERE you want inside your home...with NO wiring. Uh, switches? end up with those tiny automobile key lock button switches. I designed built-in WPT to supply up to 1500W for a room in a 'modernized' home. You could place cooking appliances/coffee makers, etc essentially anywhere in the room with no wiring to the appliance.

Wow! What was the power transfer efficiency? Were there any constraints on conductors within this space? How did you confine the field so that FCC wouldn't object to this system?

On a sunny day (Fri, 5 Apr 2013 06:32:10 -0700 (PDT)) it happened Robert Macy wrote in :

It is called flash lights, those use batteries. Nuculear batteries parhaps in the future.

eeh, why not cap the lights, tricity is free no?

MIT sold it to Boeing, hope they did not put it in that dream-flyer.

Tesla is dead, and EMC is a keyword, would not want to live an room like that,

:-)

Works great! Cooks up the occupants to medium rare ;-) ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| Phoenix, Arizona  85048    Skype: Contacts Only  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.

Well, I made a semi-permanent installation in our laundry room/pantry. There was a VERY cramped ceiling fixture, so tiny that you could not fit even a small CFL, so it had just about the only incandescent lamp in the house. I suspended my planar array of 10 LEDs below the fixture, and put the transformer/rectifier and LM3404HV regulator above it. I got one of those Edison base to wall plug adaptors and plugged the transformer into that. (I'm using a 250 mA fuse in case of oopses.) First I had this attached to the wall with no diffuser and my daughter complained about being blinded by looking at the LEDs. I have a first-cut diffuser made from a piece of scrap Plexiglas that I scratched with coarse sandpaper. I need to cut 4 sides and glue them to the diffuser to complete the fixture. I think it is going to look good as well as work quite well. This was one of those places the architect messed up a bit, the recessed fixture was not in line of sight to the pantry. With a lot more light being sprayed out below the ceiling, it lights the pantry much better.

Jon

Photos please.

?-)

Came across this today. Seems relevant to the discussion about thermal issues. It's mainly on the short life of electrolytic caps in LED lighting fixtures, and how some engineers don't bother looking at the specs carefully.

OK, here's the overall view of the laundry/pantry :

Here's a closeup of the jury-rigged fixture :

And here's a view of the LED panel :

There are 10 Cree LEDs in series on this panel, it uses the large area of copper as a heat sink. A small board with the LM3404HV regulator is on the back of the LED panel, with a bridge rectifier filter cap and a transformer.

I still need to make 4 sides of Plexiglas to finish the diffuser, but it works well and everybody appreciates being able to see stuff in the pantry. I literally used to take a flashlight in there to find stuff, the lighting was so bad!

Jon

Thank you veddy veddy much. It should be really great finished.

?-)

After some improvised tests, it seemed like this design was not giving enough light to replace the dual 48" fluorescent fixtures in the kitchen, and the pantry was a known "dark spot" in the house that needed some kind of improvement. I'm going to design an etched board for putting 15 (I think) of these LEDs on one board with the regulator/power supply in the middle. The "I think" is because 15 LEDs will drop about

45 V, and that may be too close to the HV limit of the regulator chip. I'll have to study the datasheet a bit to decide if that still has enough margin or not.

But, at least this prototype allows me to get some real life use of the design while I'm making up the next step. The kitchen fluorescents are just hanging above a suspended ceiling, so no fixture or custom diffuser will be required. I think the plastic sheet diffusers there will work fine, there will be obvious "hot spots" but they shouldn't be painful to the eyes.

Jon