Remote Living > Lighting

Led master class Parts 1 thru 5

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commanda:

http://www.otherpower.com/images/scimages/2006/led_cct_51.pdf
Hopefully this will be a little easier to read.
Amanda

BigBreaker:
Commanda, is there any reason your circuit couldn't be the driver for an IR blaster?  The switching speed would need clean edges on the order of 40khz.  I'm a bit rusty on using transistors in the forward active region.

georgec:
well I'm kind of too late for the party I hope some of you are still around to answer some questions, I have been tinkering with LEDs lately, various batteries and renewables options, it all started with an interest in solar panels but it never made much sense the way it is commercially done.
bit off topic but a 18v panel charges a 12v dc battery, which than gets inverted to 110 AC grid or not through wiring to your average department store expensive bulb which has some sort of PS built in to step it down to 3.6v DC I assumed
well I now know LEDs are current devices, just reading the specs I was stuck on the voltage myself,

Initially my thought was to build a custom panel just for the lighting in the house, to charge a lithium parallel pack, or a 20AH pouch, lifepo4 ranges, 3.2v to 3.6 , I also have some lipos 3.6v to 4.1v, with sensible sizing say a 9 cell panel would safely charge such a cell which I thought could power parallel arrays of leds, no fancy electronics, and it works I tinkered a bit last fall but I did notice the current readings varied a lot, what can I say I am simple but little did I know.

I also caught some bad feedback about transmitting 3.6v over large distances, I knew DC drops more than AC did not think it was proportional to length more than the operating voltage, I don't know the math there but apparently same drop occurs at 3v as it does at 24v so very inefficient I am told, could it work or bad Idea? I honestly only know enough to follow this thread and get myself in trouble.

ok so enough intro, I am glad I came across this presentation, especially on a forum based around renewables, I was recently looking at putting together a small 24v setup to run some powertools, I am looking to build something in the country and thou electricity is available, why bother and not do this the hard way :)

the idea was to start out modest and by the time the house is built I may not even bother and call the utility company

so obviously there are many ways to go about it but what is a proper one?, this last 24v setup was rather interesting, could one squeeze 7 leds in series?. most of your batch tested about 3 v, ( I have to go back ad read it again bit confused now ) 2 low batteries 22v, on the high end 30v, that is a bit of a gap but I guess that is why the circuitry. I was also looking into some sort battery/charge controller for my setup, I've built more complicated boards for lithium ( not of my design, I had help, I just built it, literally as in solder by numbers ), with that said I was looking into proper voltages for long led acid life, I believe 11v is already too low, 12.2v I thought would be a proper LVD, I have to ask that elsewhere but for the sake of conversation, in this instance since power would be disconnected say below 12.2v and LEDs wont work at all, should I than look at building an 8 series array? I read all series is best and the more the merrier why the question.

which than takes me even further to rather arrange my small setup at 48v than and do a 16s array but unfortunately I am not sure how that would work for the rest of my stuff, this all started with repurposing an old set of 24v cordless tools, and make them corded and run off a central battery bank powered by solar, maybe 24v is good enough but either way I like the idea and I'd like to build several such LED arrays and wire the house lighting this way right off the bat ( we'll see how the inspector feels about that, or maybe what he don't know ..............)

also while we're at it wonder if I could pull this off in automotive applications, headlights is a bit ambitious, but maybe dome light and indicator lamps, last I looked it up they were too expensive , maybe this is the way
 
anyway I'll go back and read up again while waiting for some advice

Mary B:
There are commercially available LED power supplies now, no need to invent the wheel. Jameco is one that carries them. Have one per room for all lighting in that area so your low voltage only has to go a few feet and wire the house at your battery voltage.

georgec:
why not reinvent the wheel? there is no progress without innovation or attempt of, if I run the house at battery voltage, say 24v for example, why not build such a current regulating circuit, could be per light or heck a central one right off the lighting circuit breaker, provided it is suitable for the demand, and build light fixtures of 6-8 leds with the equalizing resistor all in parallel of each other.

If going the commercial route, brings up other questions, what are those drivers made of and how do they drive the lights and cost and what LED fixtures to use with them, if I were considering the commercial route, I could simply run the house on 110v AC, inverted of the battery bank and use commercially available LED fixtures, but where is the fun in that.

my Whole interest in this circuit is the simplicity, I don't see any reason to go from a DC source such as a PV panel, through an inverter, grid tied or not, to a commercial bulb which has a driver built in to step it back to a low voltage DC where I first started with, it's silly I think, but by all means I am no authority just passionate so I wont even attempt to argue because honestly I am not qualified to do so. I could barely follow the thread and somewhat understand the concept, my electronic skills are illiterate at best. which brings me to my second interest in this project, I like to build stuff, and learning something new and I always have a great degree of respect for people such as the OP for taking the time to school others like me, I just got to put it in practice now to graduate the class.

so the question still remains, how to best set this up, I believe 24v DC is pretty common for pv setups the Ghurd controller is capable of 24v, another project I am looking into so I recon no sense in looking at 48v or further at this time, the op chose 6 leds, for the prototype, can it be done with 7?at a low of 11v / battery a total of 22v should drive 7 LED's in series, besides I believe it make a better arrangement with 1 in the middle surrounded by 6, the other question is how much light will it output I believe it was  20 000 mc each for your average 5mm, not sure how that compares to incandescent watts ( my point of reference ) most fixtures hold 3 lights so a total of 18 to 21 LEDs per fixture I figure should light up the room just fine, just lots of questions as to wire gauge and voltage loss per foot ( maybe that is why 6S is better ), can it be done with a main current regulating circuit and have the actual lighting devices made of LEDs and equalizing resistor only, I am most certainly not knowledgeable enough to figure it all out yet, not sure how much current those components can handle or in other words how many strings of LEDs can they power?, I have 8 ceiling fixtures in my current house, say 12 for the new build, at 3 strings each, 36 total, can that circuit handle it, should I split it in halves or maybe 3 strings in max one per fixture?

look forward to hear back even if its geared towards a commercial application, I can keep an open mind

George

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