Can a "normal" LED converter be used w/wired power?

[gearbox]

I have a selectable output voltage, fixed mA, AC to DC transformer and I would like to wire up some Crees or SSCs for what would basically be a cabinet light.
Is this adviseable with your run-of-the-mill driver, the types found on DX? Of course I would select the proper voltage, but is mA or mAh an issue? I don't think it is pulsing DC or anything weird, but would that be a problem? I can supply an actual photo of the packaging and whatnot if needed.

 

[VidPro]

certannly, people have used flashlight curcuits in cars, boats, and homes.
about anything can be used as a power source, the led doesnt mind as long as its the right current .
if the DC is a little dirty and pulsing a bit, a capacitor can be added that will clean up stuff like that.

which leaves some other issues, and the most common ones.
if you get some regular switching power supply wall wart or whatever, and you run it at its SPEC MAX current, over time the thing will choke, melt, overheat, die.
so most of the cheap power supplies you could drive something with , you would want to use about 1/2 thier Max current, on a continuous basis, or months or year later it will fail. so you get a 1amp supply and use it at 1/2amp continuous.

after you get things to low voltages , the length of wire will start becomming really important, the small ammount of restanace in the wiring will effect your low voltages a lot. so people often put the drive curcuits IN the fixture, and run the power to the fixture to reduce the wire lengths on the low voltage stuff.

 

[gearbox]

Let's say I wanted to power a 3.7V P4 at 800mA (mAh?).
My adaptor (transformer) can operate at 3, 4.5, 6, 7.5, 9, or 12 volts at a fixed 1200mA.
Could I wire the leads of the transformer to a "3.6V-9V 800mA board" and select something in the middle like 6V to put out a nice healthy supply to the emitter? I don't know mA vs mAh but you're saying I need to run it close to 50% of its amperage. The 800ma that the board supplies means it will only DRAW 66% of what I'm assuming is a mean transformer current, right?

What if I want to run multiple drivers and multiple emitters off of the single supply? Do I use lower mAh drivers or do I not have to worry about it? Or should I get a high current transformer and let the driver pull minimal current?

Sorry for the dumbish questions, I know just enough about electronics to be thoroughly confused :duh2:
Thanks!

 

[VidPro]

sounds good, smart to not get a "boost" curcuit, when your starting with highe voltages.
so this "buck" type of curcuit is a good choice.

its outputting 800-850, and nothing is 100% efficient, so what it Draws, could be higher than that.
if its a DC DC converter, and not just tossing out the extra voltage , then running it with 9V input the draw on your power supply should be about 400ma or somewhere around there.
so 6 or 9 volts, and yup that should all work correct.

if you want multiples, you have many choices,
first you might get 2 running off that thing in parellel, wired the same way the first one was, and wired to the power supply the same way, as long as its a dc-dc, and you start with the 9v.


or START with a higher voltage, and run something in seires. you see when you HAVE higher voltages (instead of 2 battereis) its more efficeint to have multiple leds in series. no use downconverting everything at huge losses, when you could just drive off of what you already have.
If your Power source will do 7.5v, why not just run 2 Leds off it ?
ahh cause then it wouldnt be perfectally regulated, and it might be a bit hot for your average cree led.
you usually cant put driver curcuits in series, cause they are changing around to much, and could effect eachother.

but i have used 12V type sources , and just put the correct ammount of leds in, and some resistance, and for far less money driven sets of series parellel leds for years now with no problem.

 

[VidPro]

so take your 12v power supply there, and say you want to really get some light going.

first , know that the 12V supply might vary a bit in voltage, could get to 14v unloaded, no bigee, because your going to load it, its just something to know.

we want to draw from it a max of say 600-800 ma. i really think going to 1000ma is to high for them things when continuous.

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put 3 leds in series, a bit of resistance, and plug it straight in.
adjust the resistance a bit to get to a good drive current, which would want to be lower than spec, cause you can get spikes and things.

find one of them LED resister calculators, and find out what your resistance should be, test using a Ampmeter, and adjust your resisntace a bit as needed. http://www.ledcalc.com/
then get a 2W wire wound 100ohm resister, toss it in and have a dimmer.

Cheap, easy, and , , , ok just Cheap really cheap.

 

[gearbox]

Thanks for the info, VidPro. I saw that LEDcalc before but thought it was a program I couldn't run on my Mac, or maybe it was an expired mirror to a previous version. That calculator is nice to have!

 

[Mash]

have a try here as well for a resitor calculator.