DIY LED Lighting: Homebrew Power Supply/Controller Ideas

[chayced]

I'm currently playing with an idea to convert my living room and family room to LED lighting, however nothing on the market fits my needs so I'm thinking of a homebrew solution.

I want to use a computer power supply or other stable 12volt source and then build a current regulator/dimmer possibly tying into X-10 control.

My question is this, does anyone have any experience with permanently installed LED lighting? Is making a homebrew power supply/controller reasonable or is it more trouble than it's worth? Is this something I am going to need to rip out if I decide to sell the house? Any recommendations on circuit design?

Thanks in advance!

 

[mgb_phys]

I would look at existing 12V transformers meant for fluorescent lights - they are cheap and UL etc certified. Running any kind of home brew wiring, even cat5, can cause all sorts of troubles with insurance and buyer inspections.

You can then run regular 110v (or 220v) household wiring to the light fitting. Running high current 12V DC around the house would need some expensive cable and a lot of rewiring.

ps If you are doing this for energy saving I'm not sure LED beats CF yet in practice. The trouble with LED is that they are rather too directional so you need a lot of LEDs to give a typical diffuse home lighting.

 

[chayced]

Well, the plan for the living room is pretty cut and dry. I want to go with LED lighting at the fixtures because it is dimmable vs CFLs. May just go with the LED bulb replacements, but I have yet to see one that said it was dimmable.

For the family room I would like to go with a three color LED setup so that I can change the lighting color to fit the mood. Also dimmability is a must.

Energy savings isn't my main goal, although I would much rather dimmable LEDs vice incandecents. Also I never want to change a lightbulb again.

 

[brewnog]

I fitted LED lighting (230V) in my bathroom last year. The quality of light was horrendous; it was really harsh and the colour was really cold. I switched to halogens after about a fortnight.

 

[chayced]

Yeah, 'Cool white' LEDs should say 'Blue and ugly' also 'Warm white' LEDs should say 'Very Yellow white'. Best I have seen for good looking lighting is a mixture of both to soften out the spectrum. Kinda like you do with fluorescents.

 

[dlgoff]

You might want to take a look at this PDF:
"www.netl.doe.gov/ssl/PDFs/DimmingLEDs.pdf"[/URL]
[QUOTE]Will LEDs solve the dimming problem?
LEDs face a dimming challenge similar to that of CFLs: their electronics are often
incompatible with dimmers designed for incandescents.[/QUOTE]

 

[mgb_phys]

The efficent way to dim LEDs is just to turn some of them off.
Since you need a lot of them in each light fixture to give the same output power and distribution you can turn off individual elements to give you a range of brightnesses.
You need some digital control circuitry in the lamp to do this, but no special power supply.

 

[berkeman]

ON Semiconductor makes some good DC-DC ICs for driving LEDs. Their website is very slow at the moment, or I'd give you a link.

And as said, you dim LEDs by using PWM drive of the LED current above the flicker fusion frequency of the eye.

 

[flopp]

Try these panels which now can be dimmed by remote control

 

[pantaz]

I don't have specific part numbers handy, but I know at least a couple of chip manufacturers are offering RGB LED drivers to customize your own lighting color/temperature.

 

[sophiecentaur]

I think it's just a matter of biding your time and waiting until the manufacturers come up with some decently coloured LED sources. All the present domestic ones I've seen appear to be disgusting. AND YET they have the nerve to suggest that they have a colour temperature! Unless it's a black body, it won't have a colour temperature - it will have a spectrum, and that's all they should say.
Unlike colour TV, which can produce any colour it likes, within its gamut (using efficient phosphors with almost any spectrum shape), for lighting, you need to have a continuous spectrum covering all wavelengths so that any object will get the appropriate levels of light energy at the particular wavelengths it reflects.
I wonder what the actual efficiency of LED sources with that quality is likely to be. At least it will be possible to produce arrays with multiple colours. But couldn't they do the same with CSL bulbs, using multiple phosphors on the surface?

 

[neonguy]

Leds are used extensively in the sign business these days. Dimmers, power supplies etc. are available from an electric sign supplier . Allanson and Sylvania make products with the ability to change colors but it can get expen$ive.

 

[sophiecentaur]

Yes but what you want in a sign is a certain colour, just like for a TV and this is fairly easy to achieve. When you want to light a room, you don't just want a nice coloured light. The light has to have a continuous spectrum so that familiar objects look the right colour. This can only be because light of all wavelengths is falling them. That's an entirely different requirement. I think is is a bigger problem than people appreciate - or suitable LEDs would be available for lighting. Has anyone actually seen one?
I did read of some expensive ("colour-adjustable") LED lighting for use in operating theatres - don't know what the actual subjective quality was like. The advantage there is that the light is totally cool and doesn't fry patients and staff.